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MLT Clinical Chemistry > Unit 1 > Flashcards

Unit 1 Flashcards

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1
Q

Define calibrate

A
  • assessing, setting or correcting a device usually by comparing or adjusting it to match or conform to a reliable, known, and unvarying measure
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2
Q

Define calibration

A

Actual process used to calibrate a device

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3
Q

What are the criteria for Clinical laboratory Reagent water (CLRW)?

A
  • Resistivity
  • microbiological impurities, colony forming units per mL
  • organic, total organic carbon (T O C),
  • silicates
  • particulates
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4
Q

What must a purchaser consider while purchasing a water-purification system?

A
  • review the criteria established by CLSI
  • ensure all appropriate filters and components are included
  • determine source of feed water or tap water that will be purified
    —> may contain unique contaminate or may have high mineral content (hardness)
    —> will often require the inclusion of additional components to remove these substances
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5
Q

What methods are used to produce CLRW?

A

1) purification
2) distillation
3) Resistivity
4) Reverse osmosis (RO)
5) deionization

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6
Q

Describe purification process to produce CLRW

A
  • traps any particulates before the water is sent on to the next process
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7
Q

Describe distillation process of producing CLRW

A
  • liquid is vaporized and condensed to purify or concentrate a substance
  • water that is only distilled does not meet the specific resistivity requirements for CLRW
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8
Q

Describe Resistivity method for producing CLRW

A
  • electrical resistance in ohms measured between opposite faces of a 1.00-cm cube of an Aqueous solution at a specified temperature for CLRW
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9
Q

Describe Reverse osmosis method of producing CLRW

A
  • water is forced through a semipermeable membrane that acts as a molecular filter.
  • removes
    —> 95-99% of organic compounds, bacteria and other particulate matter
    —> approximately 95% of all ionized and dissolved minerals (but will not remove gaseous impurities)
    -RO alone does not result in the production of CLRW
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10
Q

Describe deionization methods for producing CLRW

A
  • passing water through insoluble resin polymers that contain either anion- or cation-exchange resins
  • the resins exchange hydrogen ions (H+) and hydroxyl (OH-) ions for ionized impurities in the water
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11
Q

Describe carbon filters for purification

A
  • contains activated charcoal
  • helps remove organic compounds
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12
Q

Describe monitoring water purity

A
  • purity must be monitored on a consistent basis
  • at a minimum, resistivity and bacterial content should be monitored on a consistent basis
    —> most water-filtration systems will have a Resistivity meter
    —> for bacterial contamination, water should be allowed to run from at least one minute
    —> aliquot of water is obtained and plated onto an appropriate growth medium
    —> number of colony-forming units on the agar plate is determined
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13
Q

Describe use of CLRW

A
  • preparations of reagents
  • as a diluent for controls and calibrators
  • to flush and clean internal components of analyzers
  • to serve as a medium in heating bath to incubate cuvettes,
  • to wash and rinse laboratory glassware,
  • advisable to use only CLRW water for most laboratory procedures
  • when special chemistry testing is required, should use special reagent water (SRW) and CLRW
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14
Q

What does frequency of testing/monitoring of CLRW depend on?

A
  • composition of feed water
  • availability of staff to perform the test
  • amount of water used in the lab
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15
Q

Describe particulate or bacterial filter of purification of CLRW

A
  • can be added at the end of system
  • has an extremely small pore size
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16
Q

The higher the ion concentration in water, the ______ the resistivity is

A

Lower

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17
Q

CLSI requires CLRW water to have a Resistivity greater than _____

A

10 M^ . Cm (I tried)

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18
Q

Describe chemical grades

A
  • exist in varying degrees of purity
  • chemicals acquired for reagent preparation are characterized by a grading system
    —> greatly influenced by purity
    —> type and purity is usually stated on the label affixed to the chemical container
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19
Q

What are less-pure chemicals not suitable for use many quantitative assays?

A
  • practical
  • technical
  • commercial
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20
Q

What are the acceptable chemical grades for lab use deemed by the American clinical society?

A
  • analytical grade (AG)
  • reagent grade (RG)
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21
Q

What are some ultra pure chemicals?

A
  • spectrograde
  • nanograde
  • HPLC grade
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22
Q

Describe pharmaceutical chemicals

A
  • are produced to meet the specification defined in the:
    —> The United States Pharmacopoeia (USP)
    —> The National Formulary
    —> The Food chemical index
    -
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23
Q

What are the standards and purity levels for certain chemicals developed by the International Union for Pure and Applied Chemistry (IUPAC)?

A
  • atomic weight standard (grade A)
  • ultimate standard (grade B)
  • primary standard (grade C)
  • working standard (grade D)
  • secondary substance (grade E)
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24
Q

Describe the National institute of standard and testing (NIST)

A
  • good source for highly purified chemicals, especially for reference materials
  • defines its chemical and physical properties for each compound
  • provides certificate documenting their measurements
  • provides standard reference materials (SRMs) in solid, liquid or gaseous form
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25
Q

What are the two professional organizations that can provide laboratory staff with guidelines for proper chemical selection and reagent preparation?

A

1) CLSI
2) College of American Pathologists (CAP)

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26
Q

What are the types of glassware used in the laboratory?

A
  • borosilicate
  • low actinic
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27
Q

Describe borosilicate glassware

A
  • commonly used in clinical laboratories. (Beakers flasks, test tubes)
  • characterized by a high degree of thermals resistance
  • low alkali content and free of heavy metals
  • examples: Pyrex and Klimax, commercial brands
  • concentrated alkaline solutions in borosilicate glass will etch or dissolve the glass and destroy calibration.
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28
Q

Describe low actinic glassware

A
  • high thermal resistance
  • Amber or red color added
    —> gives maximum protection to light-sensitive materials
  • commonly used in containers for control material, calibrators, and reagents
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29
Q

What are the types of plasticware used in the laboratory?

A

1) polypropylene
2) polyethylene
3) polycarbonate
4) polystyrene
5) teflon

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30
Q

Describe polystyrene plasticware

A
  • rigid, clear type of plastic
  • should not be autoclaved
  • used in capped graduated tubes and test tubes
  • will crack and splinter when crushed
  • not resistant to most hydrocarbons, ketones and alcohols
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31
Q

Describe Teflon plasticware

A
  • brand name for polytetrafluoroethylene (PTFE)
  • widely used for manufacturing stirring bars, tubing, cyrogenic vials, and bottle-cap liners
  • almost chemically inert
  • suitable for use at a temperature ranging from -270 to 255 C
  • resistant to a wide range of chemical classes including hydrocarbon, alcohols, acids and bases
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32
Q

Describe polypropylene plasticware

A
  • plastic pipette tips are primarily made of polypropylene
  • may be flexible or rigid
  • chemically resistant
  • can be autoclaved
  • used in several tube designs
  • can withstand temperatures as low as -190C
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33
Q

Describe polyethylene plasticware

A
  • may bind or absorb proteins, dyes, stains, and picric acid (care must be taken)
  • used for test tubes, bottles, graduated tubes, stopper, disposable transfer pipettes, volumetric pipettes, and test tube racks.
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34
Q

Describe polycarbonate plasticware

A
  • used in tubes for centrifugation, graduated cylinders and flasks
  • not suitable for use strong acid, bases and oxidizing agents
  • may be autoclaved but with limitations
  • not stable in a temperature range of -10 to 160 C
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35
Q

Describe pipettes

A
  • used to reconstitute lyophilized controls and calibrators, prepare serum and plasma dilutions, and aliquot specimens
  • high degree of accuracy and precision is required
  • two general categories:
    —>transfer (volumetric) and Oswald pipettes
    —> measuring graduated pipettes (serological and “more” pipettes
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36
Q

What are the 3 types of pipettes?

A

1) TC (to contain)
2) TD (to deliver)
3) TD/blowout (to deliver/blowout)

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37
Q

Describe TC pipettes

A
  • rinse with diluent after they are delivered by gravity
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38
Q

Describe TD pipettes

A
  • does not need to be rinsed with diluent after being delivered by gravity
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39
Q

Describe TD/blowout pipettes

A
  • need last drop to be blown out with a mechanical device (bulb)
  • indicated by double rings or etched ring
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40
Q

Describe Class A Designation

A
  • manufactured and calibrated to to deliver the most accurate volume of liquid
  • specifications are defined by NIST
  • must be of certified accuracy by the manufacturer or volumes of liquid
  • Letter A appears on all pipettes that conform to the standards
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41
Q

Describe transfer pipettes

A
  • designed to transfer a known volume of liquid
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42
Q

Describe measuring pipette

A
  • scored in units such that any volume up to a maximum capacity is delivered
  • if two etched lines are visible, it is a blowout
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43
Q

Describe micropipettes

A
  • capable of delivering liquid volumes from 1-1000 uL
  • 2 types:
    —> air displacement
    —> positive displacement
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44
Q

Describe air displacement pipette

A
  • uses a piston device to facilitate aspiration and ejection of liquids
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45
Q

Describe positive displacement pipette

A
  • uses a capillary tip made of glass or plastic to transfer liquids
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46
Q

Describe a volumetric transfer pipette

A
  • calibrated to deliver accurately a fixed volume of an aqueous solution
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47
Q

Describe Ostwald-Folin pipettes

A
  • are similar to volumetric pipette but have their bulb closer to the delivery tip and are useful for the accurate measurement of viscous fluids such as blood or serum
  • has etch ring near mouth piece, indicating it is a blowout
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48
Q

Describe pipette calibration

A
  • required in most laboratories licensed by their respective states
  • micropipettes: should be verified for accuracy and precision before they are put into use and should be monitored through the course of the year
  • may take several hours to properly evaluate precision and accuracy of all pipettes used in the clinical laboratory
  • CLSI has provided a gravimetric procedure
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49
Q

Describe volumetric flask

A
  • have a round flat bottom and a long, thin neck with a calibration line etched near the top
  • often used to prepare standard solutions for quantitative procedures
  • usually used to prepare reagents and should consider: Flask size, thermal stability, and chemical inertness
  • accuracy is critical
  • used to contain an exact volume when the flask is filled to the mark
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50
Q

Describe Erlenmeyer flask

A
  • may be graduated or not
  • designed to hold different volumes rather than one exact amount
  • often described as “conical flasks”
  • wide flat bottom that gradually constricts to a smaller short neck
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51
Q

Describe Griffin beakers

A
  • can be glass or plastic
  • can hold different volumes rather than one exact amount
  • flat bottom, straight sides, and an opening that is as wide as the flat base
  • small spout in the lip for safe pouring of liquids
  • used for preparation of reagents and a container to hold variety of liquids for many purposes
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52
Q

Describe Graduated cylinders

A
  • used to measure large volumes of liquids
  • measured volumes are not as accurate as volumetric glassware
  • a long, cylindrical tube, typically standing upright on an octagonal or circular base
  • calibration marks along its length with different gradations
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53
Q

Describe weighing substances

A
  • fundamental process in preparing standards and reagents, performing gravimetric analysis, calibration
  • requires an analytical balance
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54
Q

What is weight?

A

A function of mass under the influence of gravity and is equal to the mass multiplied by gravity

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55
Q

What are the types of balances?

A
  • unequal-arm substitution balances
  • magnetic force restoration balances
  • top-loading balances
  • electronic balances
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56
Q

Describe the unequal-arm substitution balances

A
  • typically a single-pan design
  • commonly used, although electronic balances are replacing almost all of these types of balances
  • operates on the principle of removing weights
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57
Q

Describe magnetic force restoration balance

A
  • single-pan balance
  • the restoring force required to put the balance back into equilibrium
  • operator adjusts the internal weights and restores partial equilibrium.
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58
Q

Top-loading balances

A
  • single-pan, top loading
  • especially suitable for quickly weighing larger masses
  • not as analytical accurate
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59
Q

Describe electronic balances

A
  • built-in taring
  • interface with computers to provide calculations
  • fundamental design allows for faster weighing
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60
Q

Describe calibration of balances

A
  • no fixed calibration interval for scientific applications, according to NIST
  • intervals should coincide with the requirements of licensing and accrediting organizations
    -ASTM provides calibration weights ranging from a few milligrams to larger weights
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61
Q

What are several factors that could affect the performance of balances?

A
  • temperature
  • air drafts
  • table instability
  • static electricity
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62
Q

What are some balance specifications?

A
  • capacity
  • accuracy
  • linearity
  • readability
  • repeatability
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63
Q

Describe capacity of balance specifications

A
  • maximum load one can weigh
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64
Q

Describe accuracy of balance specifications

A
  • closeness of the agreement between the measured result and the true value
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65
Q

Describe linearity of balance specifications

A
  • ability of a balance to follow the linear relationship between load and the displayed value
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66
Q

Describe readability of balance specifications

A
  • smallest increment of weight that ca be read on the display
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67
Q

Describe repeatability of balance specifications

A
  • ability of a balance to produce the same results for repeated weighing of the same load under the identical measurement conditions
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68
Q

What is mass?

A

An object is a measure of the amount of material in it as evidenced by its inertia

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69
Q

What is inertia?

A

A measure of resistance to change of motion

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70
Q

What are the main components of a centrifuge?

A
  • motor
  • drive shaft
  • rotor assembly
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71
Q

Describe centrifuges

A
  • electromagnetic drive motor provides speeds required to separate particulates from samples
  • motors use carbon brushes to facilitate creation of electromagnetic fields that ultimately make the drive shaft turn. This in turn spins the rotor assembly
  • Buckets hold tubes containing samples
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72
Q

Describe Relative centrifugal force (RCF)

A
  • method of comparing the force generate by various centrifuge on the basis of their speeds of rotation and distances from the center of rotation
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73
Q

What is the formula for RCF?

A

RCF = (1.118x10^-5)(r)(rpm)^2

-1.118x10^-5 = empirical factor
- r = radius in centimeters from the center of rotation to the bottom of the tube in the rotor cavity or bucket during centrifugation
- rpm^2 = total number of revolutions per minute squared

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74
Q

Describe Revolutions per minute (RPM)

A
  • unit of expressing the number of complete rotations of a rotor occurring per minute
  • a measure of speed
  • most centrifuges used in clinical laboratories operate by setting the speed in RPMs
  • some procedures mandate a specific RPF
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75
Q

What is the formula for RPM?

A

RPM = SQUARE ROOT OF: RCF/(r x 1.118) x 1000)

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76
Q

What are the types of centrifuges?

A

1) swinging-bucket rotor
2) fixed-angle rotor
3) air-driven ultracentrifuge
4) ultracentrifuge
5) refrigerated

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77
Q

Describe the swinging-bucket rotor

A
  • routinely used to separate from serum or plasma
  • required relative centrifuge force is 1000-1200 x g
  • centrifuge times are between 5-10 minute
  • allows the tubes to assume a horizontal position when the centrifuge is at maximum g force
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78
Q

Describe fixed angle rotor centrifuge

A
  • allow tubes to be centrifuged as angles ranging from 25-52 degrees depending on the design
  • aerodynamically designed to yield much faster rotational speeds or greater g forces than swinging- bucket rotors
    —>one design allows for a quick 2-minute spin at nearly 4400 x g (8,500 RPM)
    —> used for preparation of stat samples
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79
Q

Describe air-driven ultracentrifuge

A
  • functions by directing compressed air onto grooves that are etched into the outer surface of the fixed-angle rotor
  • maximum RCF is about 17,800 x g
  • often used to “clear” or remove lipid particles from lipemic specimens
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80
Q

Describe ultracentrifuge

A
  • much larger than regular laboratory centrifuges
  • often floor-model types
  • generate very high centrifugal forces- for example, 800,000 x g (100,000 RPM)
  • used to fractionate lipoproteins, perform drug-binding assays, and prepare tissue for hormone receptor assays
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81
Q

Describe refrigerated centrifuges

A
  • used routinely in laboratories for separations requiring colder temperatures
  • temperature ranges from -15 C to + 25 C are achievable
  • equipped with either swinging buckets or fixed-angle rotors
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82
Q

What stage of testing is operation, maintenance and calibration of centrifuges?

A

Pre analytical

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83
Q

Describe operations of centrifuges

A
  • specimens “loaded” into the containers or buckets must adjust so weight distribution is balanced
    —> otherwise, it may not start
    —> if it does start, tube may break during centrifugation
  • tubes and containers should be covered
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84
Q

Describe maintenance of centrifuges

A
  • routine maintenance includes, cleaning with an appropriate disinfectant
  • debris inside the centrifuge should be carefully removed
  • periodically check timers and speeds
  • replace carbon brushes as needed
  • refrigerated must have temperature checks
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85
Q

What can centrifugation speeds be calibrated by?

A

Strobe tachometer

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86
Q

Describe water baths

A
  • routinely used to incubate or warm solutions
  • should offer variable temperature control from +5 C above ambient temperature to 100 C
  • types:
    —> circulating (moves water through water and provides best temperature control).
    —> non circulating
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87
Q

Describe maintenance and quality control for water baths

A
  • use reagent-grade water rather than tap water.
    —>accumulation of mineral deposits can affect temperature-sensing element.
    —> weak hydrochloric acid solution will dissolve deposits
  • 1:1000 dilution of thimerosal (Merthiolate) can be added to help prevent bacterial growth
  • overheating and subsequent damage can occur if water is allowed to completely evaporate
  • thermometer calibrated against a certified NIST thermometer must be a component
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88
Q

Describe heating blocks and dry bath incubators

A
  • commonly used for incubating liquids at higher temperatures
  • efficiency is less than circulating water bath
  • constructed of aluminum alloy that is capable of uniformly distributing heat
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89
Q

Describe heating ovens

A
  • used in chromatography procedures
  • types include programmable, vacuum, and standard laboratory
  • temperature control is usually +/- 1 C
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90
Q

Describe mixing

A
  • operation intended to form a homogenous mass or create a uniform homogenous system
    —> bringing solids into solutions
    —> bringing phases into intimate contact (for instance, in extraction procedures)
    —> washing suspended solids
    —> homogenizing liquid phases
  • improper mixing or failure to mix solutions can cause errors in laboratory testing
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91
Q

What are the types of mixers?

A
  • single tube mixer
  • multiple-tuber mixer
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92
Q

Describe single tube mixers

A
  • vortex mixer
    —> variable speed oscillations- swirling motion of liquid
    —> angle of contact and degree of pressure can be regulated
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93
Q

Describe Multiple-tube mixers

A
  • can accommodate a number of tubes and tube sizes and provide different types of
  • rotary mixers use a circular motion on a tilted disk which provides continuous inversion of contents in tubes
  • rocker type: operates by tilting back and forth in variable speeds
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94
Q

What are the special applications of thermometry?

A
  • osmometry
  • refrigerated centrifuges
  • refrigerated reagent compartments of automated analyzers
  • warming compartments of automated analyzers
  • circulating water baths for cuvette compartments in automated analyzers
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95
Q

Describe quality control of thermometry

A
  • QC procedures must be carried out and documented
  • Any temperature device that fails to perform within established tolerances must be replaced
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96
Q

What are the 2 types of thermometers in the laboratory?

A

1) total-immersion thermometers
2) partial-immersion thermometers

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97
Q

Describe total immersion thermometers

A

-bulb and entire column of liquid must be immersed into the medium measured

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98
Q

Describe partial-immersion thermometers

A
  • bulb and stem must be immersed to immersion line or defined depth on the thermometer
  • water baths and heat blocks
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99
Q

What are special applications of temperature sensing devices?

A
  • thermistor
  • thermocouple
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100
Q

Describe thermistor

A
  • transducer that converts changes in temperature (heat) to resistance
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101
Q

Describe thermocouple

A
  • season that consists of two dissimilar metals joined together at one end
  • several designs, including beaded wire, probes, and surface probes
  • important feature is fast response
  • used in gas and liquid, heating compartments in automated analyzers, thermo cuvettes, and circulating water baths used in automated chemistry analyzers
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102
Q

Describe mercury free laboratories

A
  • National Initiatives seek to remove all mercury from laboratories
  • mecircy is contained in chemical reagents used by the laboratory as well as in mercury thermometers
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103
Q

What are some mercury free thermometers?

A
  • organic red spirit and pressurized with nitrogen gas
  • blue biodegradable liquid (isoamyl Benz oats and dye)
  • red-liquid thermometer filled with kerosene
  • bimetal digital thermometers and digital thermometers with stainless steel stems
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104
Q

Describe thermometer calibration

A
  • monitoring the accuracy of thermometers is necessary
  • many commercially available thermometers meet or exceed the tolerances for accuracy
  • non-certified thermometers can be calibrated by using NIST thermometer
  • temperature monitoring devices should be verified for accuracy at 6 or 12-month intervals
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105
Q

What are the 3 basic metric units?

A

Length = meter
Mass = gram
Volume = liter
- area is measured in squared units (common: mm^2, cm^2, m^2)

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106
Q

What is a meter?

A
  • defined as the distance traveled by light in a vacuum during a time interval of 1/299,792,458 seconds
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107
Q

What is a gram?

A

1/1000 the quantity of matter in the international prototype kilogram

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108
Q

What is a kilogram?

A
  • SI unit of mass
  • defined as the mass of water contained by a cube whose sides are 1/10 the length of a meter, or 1 decimeter in length
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109
Q

What is a liter?

A

-defined as the volume of liquid contained within that same cube.
- also used as a name for exactly 1 cubic decimeter, 1000cubic centimeters, or 0.001 cubic meter

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110
Q

What is area?

A
  • this is a derivation of the measurement of length
  • determined by multiplying the length times the width of a surface
  • thus, measured in square units
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111
Q

What are the 7 Base SI units?

A

1) length: meter (m)
2) Mass: kilogram (kg)
3) Time: seconds
4) Temperature Kelvin (K)
5) Amount of substance: mole (mol)
6) electric current: ampere (A)
7) luminous intensity: candela (cd)

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112
Q

What are the three classes of SI units?

A
  • base
  • derived
  • supplementary units
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113
Q

What are the systems of measurement for temperature?

A
  • Celsius (C): divided into 100 equal parts division
  • Fahrenheit (F): divided into 180 equal parts division
  • Kelvin (K): absolute zero
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114
Q

What is a conversion equation for Celsius?

A

C = (F - 32)/1.8

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115
Q

What is the conversion formula for Fahrenheit?

A

F = (1.8 x C) + 32

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116
Q

What formula would be used if you have Celsius and need to convert to Kelvin?

A

K = C + 273

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117
Q

What formula would be used if you have Fahrenheit converted to Kelvin?

A

K = (F+459.67) x (5/9)

  • 5/9 = 0.56
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118
Q

What temperature does water freeze at in C and F?

A

0 C
32 F

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119
Q

What temperature for water boil at in C and F?

A

100 C
212 F

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120
Q

What is room temperature in C and F?

A

20-25 C
68 F

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121
Q

What is body temperature in C and F?

A

37 C
98.6 F

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122
Q

Describe significant figures

A
  • minimum number of digits needed to express a particular value in scientific notation without loss of accuracy
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123
Q

Describe logarithms

A
  • defined as a quantity representing the power to which a fixed number must be raised to produce a given number
  • two part
    —> characteristic: number to left of decimal point in log; derived from exponent
    —> Mantissa: portion of log to right of decimal point; derived from number itself (always positive)
  • N = 10^x
  • Log of N = x
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124
Q

What are the negative logs?

A

PH
pKa

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125
Q

What are the formulas to determine negative algorithms?

A
  • absolute pH = x - logN
  • pKa
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126
Q

Describe percent solutions

A
  • expressed as weight/weight, volume/volume or weight/volume

%w/v = grams of solute/100 mL of solution
OR
Grams of solute/1dL of solution

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127
Q

What is the formula for molarity?

A

grams = (M)(gmw)(L)

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128
Q

Decribe normality

A

N = M x Val.

Expressed as (Eq/L) OR (mEq/mL)

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129
Q

What is Density?

A

Expressed as mass per unit volume

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130
Q

Describe specific gravity

A
  • the ratio of the density of a material when compared to the density of water at a given temperature
  • g/mL

Actual weight = specific gravity x assay value %

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131
Q

Describe dilutions

A
  • represents the ratio of contcentrated or stock material the TOTAL FINAL VOLUME of a solution
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132
Q

Describe simple dilutions

A
  • decide on the total volume desired and the amount of stock to be used
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133
Q

What formula would be used for changing concentrations?

A

C1V1 = C2V2

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134
Q

Describe serial dilutions

A
  • defined as multiple progressive dilutions ranging from more-concentrated solutions to less-concentration solutions
  • used frequently in immunology and blood bank
  • initial dilution x next dilution = final dilution
  • reciprocal of the final dilution is the dilution factor
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135
Q

Describe Beer’s law

A
  • establishes relationship between concentration and absorbance in many photometric determinations
    —> Absorbance of a colored substance is proportional to concentration
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136
Q

What is the formula use in chemical analysis?

A

Cu = (Au x Cs)/ As

Cu = concentration of the unknown
Au = absorbance of the unknown
Cs = concentration of the standard
As = absorbance of standard

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137
Q

What calibration device is used to verify the accuracy of laboratory thermometers?

A

SRM 1968 gallium melting point cell

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138
Q

What is the gmw and valence of Nacl?

A

58 g
1 valence

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139
Q

What is the gmw and valence of HCL?

A

36 g
1 valence

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140
Q

What is the gmw and valence of NaOH?

A

40 g
1 valence

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141
Q

What is the gmw and valence of KI?

A

166 g
1 valence

142
Q

What is the gmw and valence of KOH?

A

56 g
1 valence

143
Q

What is the gmw and valence of CaOH2?

A

74 g
2 valence

144
Q

What is the gmw and valence of CaCl2?

A

111 g
2 valence

145
Q

What is the gmw and valence of H2SO4?

A

98 g
2 valence

146
Q

What is the gmw and valence of Na2SO4?

A

142.04 g
2 valence

147
Q

What is the gmw and valence of BaSO4?

A

233.3 g
2 valence

148
Q

What does OSHA stand for?

A

Occupational safety and health administration

149
Q

What does OSHA do?

A
  • provides federally mandated policies and procedures to ensure safety in the workplace, including laboratories and health-care facilities
150
Q

What does CFR stand for?

A

Code of Federal Regulations

151
Q

Where are standards found?

A

CFR

152
Q

What are the four major OSHA standards that have made a significant impact on the safety practices in the laboratory?

A

1) occupational exposure to hazardous chemicals in laboratories
2) Hazard communication
3) bloodborne pathogens standards
4) revised bloodborne pathogens with needlestick safety

153
Q

What does NFPA stand for?

A

National Fire Protection agency

154
Q

What organization mandates that each laboratory establish a chemical hygiene plan?

A

OSHA

155
Q

What are some specific elements found in a chemical hygiene plan?

A
  • glossary
  • description of standard operating procedures
  • inventory of all chemicals
  • Safety Data Sheets (SDS)
  • proper labeling and storage
  • inventory of PPE
  • description of engineer controls
  • procedure for waste removal and disposal
  • training requirements
  • procedure for proper record keeping
  • designation of a chemical hygiene officer and safety committee
156
Q

What does SDS stand for

A

Safety standard sheet

157
Q

Describe operating procedures of chemical safety

A
  • lab staff should be properly trained to respond in safe manner
  • appropriate response depends on size of spill
  • wear appropriate PPE
  • response for large spill requires a higher level of expertise and coordination of departments
158
Q

Describe SDS

A
  • documents that provide information about chemical substances
  • identification
  • composition
  • hazards
  • first aid
  • fire fighting concerns
  • safe handling
159
Q

What are the 9 classes of hazardous materials, as follows:

A

1) explosives
2) compressed gases
3) flammable liquids
4) flammable solids
5) oxidizer materials
6) radioactive materials
7) toxic materials
8) corrosive materials
9) miscellaneous materials not classified by any other means

160
Q

Describe Labeling for hazardous materials

A
  • color coded to represent specific health hazard
  • degree of hazard is rated using a scale of 0 - 4 ( 4 being the most serious risk)
161
Q

What labeling information should be included if chemicals are not in their original container?

A
  • identification of hazardous chemical
  • route of body entry
  • health hazard
  • physical hazard
  • Target organ(s) affected
162
Q

Describe inventory of chemicals

A
  • keep only the amount of chemicals that is needed. Less is better
  • if possible, purchase chemicals in plastic containers to avoid breaking glass
  • rotate your chemical inventory and note expiration dates
  • dispose of chemicals if not used within a year— especially peroxide-forming compounds
  • make sure all secondary containers are properly labeled
  • if possible, relocate corrosive, flammable and reactive chemicals to below eye level
163
Q

What are some examples of poor storage of chemicals?

A
  • not in alphabetical order
  • food stored by chemicals
  • shelves are overcrowded
  • poor inventory control
  • containers store on floor
  • containers with no labeling or wrongly labeled
164
Q

Describe storing of chemicals

A
  • categorical storage of chemicals is a safe approach for separating potentially reactive chemicals.
  • flammable chemicals must be stored in a an appropriate safety cabinet
  • transferring chemicals from one container to another can result in an accident
  • transporting chemicals throughout the laboratory can be hazardous
165
Q

What would occur if acetic acid and acetaldehyde mix?

A

Acetic acid will cause acetaldehyde to polymerize, releasing a large amount of heat

166
Q

What would occur is ammonium nitrate and acetic acid mix?

A

Will ignite, especially if an acid is concentrated

167
Q

What would occur if hydrogen peroxide and ferrous sulfide mix?

A

Vigorous reaction, highly exothermic

168
Q

Describe lead perchlorate + methanol

A

Explosive mixture if agitated

169
Q

What would occur if potassium cyanide and potassium nitrate mix?

A

Potentially explosive material if heated

170
Q

What does the blue color signify on a hazard label?

A
  • health hazard
    4–> deadly
    3-> extreme danger
    2-> hazardous
    1-> slightly hazardous
    0-> normal materials
171
Q

What does the color red signify on a hazard label?

A
  • fire hazard/flash points
    4-> below 37 F
    3-> below 100 F
    2-> below 200 F
    1-> above 200 F
    0-> will not burn
172
Q

What does yellow signify on hazard labels?

A
  • reactivity
    4-> may detonate
    3-> shock and heat may detonate
    2-> violent chemical change
    1-> unstable if heated
    0-> stable
173
Q

What does white signify on hazard labels?

A
  • specific hazard
  • oxidizer (OXY)
  • corrosive (CO R)
  • acid (ACID)
  • alkali (ALK)
  • use no water
  • radiation
174
Q

Describe explosive chemicals

A
  • cause a sudden release of pressure, gas, or heat
  • when subjected to shock, pressure, or high temperatures
175
Q

Describe cyrogenic liquids

A
  • liquefied gases kept in their Iiquid state at very low temperatures
  • have boiling points below -150 C (-238 F)
  • gases at normal temperatures and pressures
  • classified as “compressed gases” according North American Industrial Classification System (N A I C S)
176
Q

What are hazards that are associated with cryogens?

A
  • fire or explosion
  • asphyxiation
  • pressure buildup
  • embrittlement of material
  • tissue damage
177
Q

Describe formaldehyde

A
  • colorless liquid
  • characteristic pungent odor
  • routinely used in laboratories for tissue processing
  • can cause respiratory cancer, dermatitis, sensory irritation (eye, nose, throat), and sensitization. Can also cause tissue damage
178
Q

Describe safety cabinets

A
  • OSHA defines the maximum amount of flammable and combustible liquids that can be stored in any laboratory with NFPA - approved flammable storage cabinets
  • Regulations are defined by the solvents classification
179
Q

Describe chemical waste

A
  • disposal of chemical waste is the responsibility of individual laboratories
  • Resource Conservation and Recovery Act (R C R A)
  • “ cradle-to-grave” responsibility and liability
  • provides for management of hazardous waste from point of origin to point of final disposal
  • promotes resources recovery and waste minimization
  • chemical waste is any hazardous, corrosive, or flammable materials are prohibited from being disposed of by pouring down sink drains
180
Q

What are some chemicals that are hazardous, corrosive, or flammable?

A
  • organic solvents with a boiling point of less than 50 C
  • hydrocarbons
  • halogenated hydrocarbons
  • nitrocompounds
  • mercaptan
  • Freon
  • azides and peroxides
  • concentrated acids and bases
181
Q

What are universal precautions in the lab?

A
  • exposure-control plan
  • biological
  • hand hygiene practices
  • needlestick regulations
  • personal protective equipment
  • biosafety levels
  • toxic substances
182
Q

What sections should be included in an exposure-control plan (ECP)?

A

1) purpose
2) scope
3) reference
4) definition
5) delineation of responsibilities
6) detailed procedural steps

183
Q

Describe exposure control plans

A
  • OSHA guidelines for this plan require that the employer place each employee into one of three groups
  • Group I
  • Group II
  • Group III
184
Q

Describe Group I of exposure-control plans

A
  • all employees face occupational exposure to blood or other potentially infectious materials
185
Q

Describe Group II of exposure control plan

A
  • some employees face occupational exposure to blood or other potentially infectious materials
186
Q

Describe Group III of exposure-control plan

A
  • employees will not face any occupational exposure to blood or other potentially infectious materials
187
Q

What are some exposure sources found in the lab?

A
  • centrifuge accidents
  • needle punctures
  • spilling infectious material on bench surfaces
  • cuts and scratches from contaminated glassware
  • removing stoppers from blood drawing tubes
188
Q

What two things do all cryogens have in common?

A

1) extremely cold
2) small amounts of liquid can expand into very large volume of gas

189
Q

Describe hand hygiene practices

A
  • transmission of pathogen most often occurs via the contaminated hands of health-care workers
  • CDC recommends vigorous rubbing together of all lathered surfaces for at least 15 seconds
  • hand hygiene is still necessary after gloves are removed
    —> gloves may become perforated
    —> bacteria can multiply rapidly on gloved hands
190
Q

What is the hand washing procedure?

A

1) turn on water faucet to a cool temperature
2) place hands under water
3) dispense one pump action volume of soap
4) rubbing briskly, wash all surfaces of hands, including between fingers, for at least 15 seconds
5) RInse thoroughly under running water
6) pat hands dry with paper towels, discarding the paper towels in a waste container
7) if using a hand operated faucet, use a dry paper towel to turn off the faucet

191
Q

Describe needlestick regulations for OSHA

A

Needles used for withdrawing blood must have a “built-in safety feature or mechanism that effectively reduces the risk of an exposure incident”

192
Q

Describe needlestick regulations of CDC

A
  • implementing measures might prevent needlestick injuries:
    —> use safe and effective alternatives to needles
    —> participate in the selection and evaluation of needle safety devices
    —> use only devices equipped with with safety mechanisms
    —> do not recap needle
    —> implement a plan that will ensure safe handling and disposal of needles
    —> immediately dispose of used needles in the proper sharps disposal containers
    —> communicate needlestick hazard to your employers
    —> participate in infection- control training
193
Q

Describe personal protective equipment (PPE)

A
  • specialized clothing or equipment won by an employee for protection against a hazard
  • general work clothes are not considered to be personal protective equipment
194
Q

What are some things that are considered PPE?

A
  • gloves
  • eyewear
  • respirators
  • laboratory coats and footwear
  • engineered controls
  • glass versus plastic
195
Q

Describe gloves

A
  • routine use of gloves to protect laboratory stay against exposure to bloodborne pathogens was mandated by OSHA in 1991
  • NIOSH has recommended that employers provide gloves with reduced protein content
  • gloves are also available to protect employees from exposure to chemicals
196
Q

Describe eyewear

A
  • conventional or prescription eyeglasses are not impervious to chemicals
  • proper eyewear is recommended
    —> provides protection to sides of the face as well as the front
    —> face shield
197
Q

Describe respirators

A
  • should contain high-efficiency particulate air (HEPA) filters if no other engineering controls are available
  • filtration respirators will require the use of one or two cartridges
198
Q

Describe laboratory coats and footwear

A
  • employers must provide proper laboratory coats to each employee
  • they must have cuffed sleeves and be full length
  • they should remain buttoned to avoid contaminating street clothes
  • the material should be resistant to liquids
  • the construction of lab coats resistant to liquids includes layers of polypropylene, spun bound filaments, and meltdown polypropylene microfibers
  • footwear should be nonporous, closed toe shoe
199
Q

Describe engineered controls

A

Safety equipment that isolates or removes the bloodborne pathogen hazard from the workplace

200
Q

What does HEPA stand for?

A

High-efficiency particulate air

201
Q

What are the 5 specimens that could carry bloodborn pathogens?

A

Plasma
Serum
Blood
Vaginal sectretions
Semen

  • HIV, HBV..
202
Q

What are examples of safety-engineered controls?

A
  • splash shields
  • biosafety cabinets
  • secondary containers
  • impervious needle boxes
  • automatic pipette
  • centrifuge caps
  • self-sheathing needles
203
Q

What are the biosafety levels?

A

BSL 1
BSL 2
BSL 3
BSL 4

204
Q

Describe BSL 1

A

Not known to consistently cause disease in healthy adults

205
Q

Describe BSL 2

A

Associated with human disease, hazard by percutaneous injury, ingestion, mucous membrane exposure

206
Q

Describe BSL 3

A

Indigenous or exotic agents with potential for aerosolize transmission; disease may have serious of lethal consequences

207
Q

Describe BSL 4

A

Dangerous/exotic agents which pose high risk or life-threatening disease; aerosol transmitted lab infections; or related agents with unknown risk of transmission

208
Q

What is a toxic substance?

A

Pose a potentially significant and long-lasting risk

209
Q

Describe xenobiotic

A
  • a substance that is foreign to a living organism and is usually harmful
  • once a xenobiotic enters the body, it circulates until a suitable cellular receptor is located
  • a xenobiotic substance that results in the production of a cancer-producing tumor is termed a carcinogen
210
Q

What are teratogens?

A
  • substances that acts preferentially on an embryo at precise stages of its development
  • thereby leading to possible abnormalities and malformations
211
Q

Describe organogenesis

A
  • describes 15th to 60th days of feta development, in which the embryo is most sensitive to the action of a teratogenic substance
212
Q

Describe fire safety in a laboratory

A
  • laboratories should have the means available to extinguish small fire in a room, confine a fire, and extinguish clothing that has caught fire
  • fire safety devices include:
    —> fire blankets
    —> safety showers
    —> fire extinguishers
213
Q

Describe fire extinguishers used in the laboratory

A
  • are designed to suppress and extinguish different classes of fires
  • classes of fires:
    —> A
    —> B
    —> C
    —> D
214
Q

Describe class A fire extinguisher

A
  • hazard: ordinary combustible material (paper, wood, cloth, rubber, plastic)
  • type: water or dry chemical
215
Q

Describe class B fire extinguisher

A

Hazard: flammable combustible liquids, gases, grease, and similar materials
Type: dry chemical or carbon dioxide

216
Q

Describe class C fire extinguisher

A
  • hazard: energized electrical equipment
  • type: carbon dioxide, dry chemical or Halotron (halon)
217
Q

Describe class D fire extinguisher

A
  • hazard: combustible metals such as magnesium, titanium, sodium, and potassium
  • type: specific for the type of metal in question
218
Q

What does RACE stand for?

A

Rescue
Activate alarm/call
Contain fire
Evacuate area

219
Q

How to use a fire extinguisher properly?

A
  • pull the pin
  • aim extinguisher
  • squeeze handle
  • spray back and forth

*PASS

220
Q

Describe compressed gases

A
  • department of transportation (DOT) regulates the labeling of gas cylinders that are transported by interstate carriers
  • gases may be:
    —> flammable
    —> corrosive
    —> explosive
    —> poisonous
    —> inert
    —> a combination of the aforementioned hazards
  • contents of cylinders must be clearly identified
  • signs must be posted conspicuously in area where flammable gases are used
221
Q

What should staff know when handling compressed gases?

A
  • dangers, if any, associated with gases they are using
  • proper procedure for securing gas cylinders
222
Q

What are electrical safety recommendations?

A
  • use properly grounded electrical circuits and devices
  • electrical wires and cords should have no frayed edges, cuts, or exposed wiring.
  • use of extension cords should be discouraged
  • multiplug adapters and cheater plugs should not be used
  • use only UL-approved, fuse protected, multiple socket surge protectors
  • use ground fault interrupters (GFIs) in areas where there is a source of water
  • keep heat sources and liquids away from outlets
  • do not handle any electrical devices with damp or wet hands
  • train employees in how to handle shock injuries
  • electrical panels should be clear of obstacles for easy access (allow atleast 3 feet from panel)
  • never work on exposed electrical devices alone
  • all shocks should be reported immediately, including small tingles
  • do not work on attempt to repair any instrument while the power is still on. Unplug the equipment
223
Q

Describe radiation safety

A
  • clinical laboratory personnel may be exposed to two types of radiation sources:
    —>non-ionizing
    —>ionizing
  • protective measures usually include some type of shielding and/or containment devices that will protect the user from direct exposure
    — eyes are the most vulnerable to radiation exposure
224
Q

Describe non ionizing radiation

A
  • emit electromagnetic radiation ranging from extremely low frequency (E L F) to higher frequency ultaviolet (UV)
225
Q

What equipment is non ionizing found in the laboratory?

A

-microwaves
- infrared lamps and lasers
- visible lamps (tungsten-halogen)
- ultraviolet lamps (xenon and deuterium)

226
Q

What are workplaces safety issues?

A
  • ergonomics
  • cumulative trauma disorders
  • noise and hearing conservative
  • laboratory hoods (ventilation)/biosafety cabinets
  • waste management issues
  • staff responsibilities
  • safety manual
  • training
  • institutional alerts
  • emergency codes
  • emergency management
227
Q

Describe ergonomics

A
  • applied science that focuses on designing and arranging objects people use so people and objects interact most efficiently and safely
  • serious complications can develop from performing challenging tasks and may render the staff member nonfunctional
228
Q

Describe cumulative trauma disorders

A
  • also called cumulative trauma syndrome, repetitive motif disorder and overuse syndrome
  • refer to disorders associated with overloading particular muscle groups from repeated use or maintaining a constrained posture
  • typically develop over weeks, months, or years
  • may involve tendons, nerve entrapment, muscles, or blood vessels
229
Q

What are cumulative trauma disorder (CTD) risk factors?

A
  • respective and prolonged activity
  • forceful exertions, usually with the hands
  • prolonged static postures
  • awkward postures of the upper body
  • continued physical contact with work surfaces, such as contact with edges
  • excessive vibration from equipment
  • working in cold temperatures
  • lack of adjustable chairs, footrest, body supports, and work surfaces at workstation
  • slippery footing
  • noise
  • lifting
  • repetitive stress issues
  • standing for long periods of time
230
Q

How should gas cylinders be stored?

A
  • kept in upright position and secured to wall using chain
  • if they fall, the valve could break off. The gas may be release at very high velocity ,causing the cylinder to propel like a rocket
231
Q

Describe noise and hearing conservation of

A
  • low-level noise or “white noice” can result in fatigue, irritation, and headaches
  • OSHA allows a time-weighted average (TWA) of 785 decibels/8 hours
  • A hearing conservation program is designed to provide an employee with proper equipment to reduce exposure to high levels of noise
232
Q

Describe laboratory hoods

A
  • also called fume hoods
  • used to ventilate unwanted fumes from chemical reagents
  • each hood should have a continuous monitoring device
233
Q

Describe class I biosafety cabinets

A
  • face velocity, 75 ft per minute
  • open front, exhaust only through HEPA filter
234
Q

Describe class II safety cabinets

A
  • face velocity, 100 feet per minute
  • recirculation through HEPA filters and exhaust via HEPA filter
  • appropriate for BSL 2 and 3
235
Q

Describe class III safety cabinet

A
  • supply air inlets and exhaust through two HEPA filters
    -appropriate for BSL 3 and 4
236
Q

What are the 3 types of waste generated?

A

1) chemical
2) radioactive
3) biohazardous

237
Q

What are the staff responsibilities for workplace safety?

A
  • don not use personal electronic devices in areas where infectious exposure is likely
  • do not wear PPE or laboratory coats outside of the laboratory
  • use splash barriers when capping/uncapping tubes, pipetting or dispensing, mixing with a vortex mixer, and making dilutions
  • do not eat or drink in the lab
  • do not apply cosmetics in the work area
  • secure hair back and off the shoulders
  • do not wear jewelers that can become caught in equipment or come into contact with biological fluids or chemical testing materials
  • do have hepatitis B vaccination
  • do not store personal belongings such as purses, coats, coffee mugs,and other personal items in the technical areas
238
Q

Describe safety manual

A
  • should be written, reviewed, and made available to all laboratory staff
  • should present defined policies, procedures, and jobs responsibilities for each member of the laboratory staff
  • may also serve as a training document
  • schedules should be developed for each safety topic that requires action.
239
Q

What are some recommended topics for clinical laboratory safety manuals?

A
  • institutional emergency codes
  • emergency phone numbers
  • biosafety levels 1-4 criteria
  • standard operating procedures (SOP)
  • PPE
  • chemical handling and inventory
  • SDS
  • bloodborne pathogens
  • fire safety
  • electrical safety
  • compressed gases
  • signs and lables
  • medical considerations
  • emergency procedures and cleanup
  • waste disposal
  • record keeping and training
240
Q

Describe training

A
  • should be considered an ongoing event
  • needs to be part of:
    —> new employee orientation
    —> laboratory staff continuing education
  • should be conducted in accordance with local, stare, and federal regulations
241
Q

Describe emergency codes

A
  • represents a means for health-care facilities to alert their employees that an adverse event in occurring somewhere in or near the facility
  • codes were developed using several different designations (colors, numbers, and names) and these codes are commonly initiated
242
Q

Describe emergency management

A
  • every institution should create an emergency management plan (EMP)
  • adoption of the National Incident Management Systems (NIMS) is typically recommended
  • management of a disaster is effectively mitigated using the incident command system
  • incident command system (ICS) is a standardized on-scene incident management concept
243
Q

Describe institutional alerts

A
  • designed to alert participants via cell phone, telephones, email, and media outlets of a significant incident occurring within/near bounds of institution
244
Q

What CFR standard is most associated with clinical laboratories?

A
  • Standard 29 CFR
  • this standard is divided into several sections that are identified using a part number with a title.
245
Q

What is the CFR code for Needlestick regulations?

A

29 CFR 1910.1030

246
Q

What is CFR code for noise conservation?

A

Standard 29 CFR 1910.95 appendix G

247
Q

What is the CFR code for laboratory hoods and biosafety cabinets?

A

29 CFR 1910.1450 appendix A

248
Q

Liquid nitrogen is an example of what?

A

Cryogenic

249
Q

A ground fault interrupter (GFI) should be used in which situation?

A
  • where there is a source of water
250
Q

The NFPA 70 4-M Identification system is associated with what?

A
  • warning labels for chemical hazards
251
Q

What is statistics?

A
  • mathematical process of dealing with the collection, analysis, interpretation, and presentation of masses of laboratory numerical data
252
Q

Describe descriptive statistics

A
  • includes the mean, range, variability, and distribution of a data set
  • commonly used in the laboratory
253
Q

Describe inferential statistics

A
  • concerned with the relationship among different sets or samples of data
  • example: comparing the mean of one set of data to another set of data
254
Q

Describe laboratory stastics

A
  • statistics should be viewed as tools that are available for the laboratory staff to use
  • knowing which tool or statistic to use is important
  • computation of most statistics is performed using computer software packages or calculators
255
Q

What are measures of central tendency?

A
  • mean
  • median
  • mode
256
Q

What is mean?

A

Average

257
Q

What is median?

A

Middle point

258
Q

What is mode?

A

Most frequently occurring value

259
Q

What are the measures of dispersion?

A

Range (r)
Standard deviation (s)
Coefficient of variation (CV)
Variance (sd^2)
Outliers

260
Q

What is range?

A
  • measure of spread or variation in a set of data
  • the difference between the largest and the smallest numbers of the data set
261
Q

What is standard deviation?

A
  • is the square root of the variance of the values in any one observation or in a series of results
  • measures dispersion around the mean
  • shape of distrubution on a Gaussian curve (bell curve)
262
Q

What is coefficient of variation?

A
  • measures the relative standard deviation divided by the mean
  • defined as 100 times the standard deviation
  • to compare one method to another
  • to compare one lab to another lab
263
Q

What is the coefficient of variation formula?

A

CV = (s/x) x 100

264
Q

What is the standard deviation formula?

A

S= (Square root of all) [SUM(x1-x2)^2]/( # of tests - 1)

  • at least 30 patients specimens are selected and test is run
265
Q

What is the formula for CV%?

A

CV% = (1SD/mean) x 100

266
Q

What are the 3 types of data presentation?

A
  • ranked
  • continuous
  • discrete
267
Q

Describe ranked data

A
  • arranged from highest to lowest according to magnitude and then assigned numbers that are correspond to each observation placed in the sequence
268
Q

Describe continuous data

A
  • represents a continuous variable that can assume any value within the range of scores that define the limits of the variable.
269
Q

Describe discrete data

A
  • a subset of continuous data
  • assume a defined set of integers
  • both order and magnitude are important
270
Q

Describe variance (sd^2)

A
  • calculated by squaring the SD
  • can also be derived by subtracting the mean from each of the values, squaring the resulting differences, and then adding up the squared differences
271
Q

Describe outliers

A
  • measurement that belongs to a population other than the one that which most of the measurement belongs
  • cans distort the computed values of stastistics
  • can cause incorrect inferences to be made about the population parameters of interest
272
Q

What does a normal distribution of analytes in a selected population look like?

A
  • continuous distribution
  • symmetric around the mean
  • predicably related to the SD or sigma, or variance
273
Q

What are the 2 types of data?

A

Nominal data
Ordinal data

274
Q

Describe nominal data

A
  • type of data in which the values fall into unordered categories or classes
  • numbers applied to non numerical values
275
Q

Describe ordinal data

A
  • numbers that are discrete and ordrered (ranked)
  • order of ranking is important
276
Q

Describe confidence intervals

A
  • keep in mind that we expect 1 out of 20 to be out of the 2 SD on either side of the Gaussian curve
  • this means that we expect 2.5 out of 100 to be above the 2SD range and 2.5 out of 100 to be below the 2 SD range
  • 2.5 out of 100 is the same as 1 out of 40 to be high and 1 out of 40 to be low
  • therefore, 95% to be within limits that means we expect 5% to be normal and outside the 2 SD range
  • 5 out of 100 is the same as 1 out of 20
277
Q

What are the applications of confidence interval?

A

1) estimating the range of values that include specified proportion of all members of a population, such as the normal or reference interval of value for a lab test
2) hypothesis testing

278
Q

Describe regression

A
  • ultimate objective is to predict or estimate the value of one variable based on a given value of the second variable
  • regression analysis is commonly used in the comparison of two methods or two instruments and to evaluate the linearity of an instrument or method
  • x-variable is independent variable
  • y-variable is dependent variable
279
Q

Describe correlation

A
  • correlation statistics measures the strength of the relationship between variables
280
Q

What are analytical performance parametes?

A
  • accuracy
  • precision
  • types of errors
  • linearity
  • analytical range
  • analytical sensitivity
  • analytical specificity
  • limit of detection
  • interference
  • stability
  • ruggedness
  • robustness
  • performance of standards
281
Q

What is precision?

A
  • ability to produce the same value for replicate measurements of the same sample
  • also described as the random variation in a population of data
282
Q

What is accuracy?

A
  • the closeness for the agreement between the measured value of an analyte to its “true” value
  • can be evaluated using proficiency testing samples
  • recovery experiments using the method of addition are also used to determine the accuracy of a method
283
Q

What are types of errors?

A
  • random
  • systematic
  • discordant results
284
Q

Describe random errors

A
  • occurs without prediction or regularity
285
Q

Describe systemic errors

A
  • error that is consistently low or high
  • constant: error is consistently low or high by the same amount over the entire concentration range
  • proportional: error is consistently low or high by an amount proportional to the concentration of the analyte
286
Q

Describe discordant results

A
  • commonly used to describe laboratory results that do not agree
  • false negatives, false, positives, errors, and inaccurate results
  • provides CLSs with one of their greatest challenges because such results often occur sporadically and may occur with some specimens but not others
287
Q

Describe linearity

A
  • quality or state of being linear
  • if the plot is linear, the range tested is termed the linear range of the method
288
Q

What is analytical range?

A
  • range of concentration in the sample over which the method is applicable without modifications
  • should be wide enough to include 95-99% of the expected samples without pre-dilution
289
Q

Describe analytical sensitivity

A
  • the slope of the calibration curve and the ability of an analytical procedure to produce a change in the signal for a defined change of the analyte quantity
  • ideally a method should have a high level of analytical sensitivity and a low detection limit
290
Q

Describe analytical specificity

A
  • ability of a method to measure only the analyte it claims to measure without reacting with other related substances
291
Q

Describe limit of detection

A
  • represents the lowest concentration or quality of an analyte that significantly exceeds the measurement of a blank sample
  • depends on the amplitude of the blank value and must be precise at the level.
292
Q

Describe interference

A
  • effects of a compound(s) other than the analyte being measured
293
Q

Describe stability

A
  • stability of reagents, calibrators, and controls must be investigated
  • impacts the laboratory in both cost and efficiency
294
Q

Describe ruggedness

A

Ability of the assay to perform in a consistent, reliable fashion when used by different operators and with different batches of reagents over an extended period of time

295
Q

Describe robustness

A
  • capacity of a method to remain unaffected by small, deliberate variation in method parametes
296
Q

Describe performance standards

A
  • need to be established before any analytical experiments are begun
  • focus is error
297
Q

Describe reference interval

A
  • CLSI has published a document that provides guidelines on how to define an determine reference intervals in the clinical laboratory
298
Q

Describe experimental phase of method evaluation

A
  • tasks performed and the order in which they are performed vary considerably from laboratory to laboratory
  • comparison of methods experiments involves measuring patients specimens by both existing (reference) and new (test) methods
299
Q

Describe screening of diagnostic tests

A
  • application of a test to indivduals who have not yet exhibited any clinical symptoms in order to classify them with respect to their probability of having a particular disease
  • screening tests are not always infallible
    —> may yield a false positive or false negative
300
Q

What issues of probability should be considered in evaluating the usefulness of test results?

A

1) given that a subject has the disease, what is the probability of a positive test result (or presence of symptoms?)
2) given that a subject does not have the disease, what is the probability of a negative test result (absence of symptoms)?
3) give a positive screening test result (or presence of a symptom), what is the probability that the subject has the disease?
4) given a negative screening test result (absence of a symptom), what is the probability that the subject dos not have the disease?

301
Q

What are some diagnostic tests?

A
  • screening
  • sensitivity
  • specificity
  • predictive value of a positive and negative test
302
Q

What is the formula for diagnostic sensitivity?

A

Diagnostic sensitivity = TP/(TP + FN)

303
Q

What is the formula for diagnostic specificity?

A

Diagnostic specificity = TN/(FP + TN)

304
Q

Describe reference range

A
  • internal between and including two reference limits
305
Q

What is reference limit?

A
  • a numerical value(s) derived from the reference distribution
306
Q

Describe reference

A
  • denotes a well-defined selection of subjects used to mathematically determine the numerical values equivalent to reference limits and thus reference interval
307
Q

What are reference intervals derived from?

A

Reference individuals

308
Q

What factors should be addressed before determining a reference interval?

A
  • selection of reference individuals
  • preanalytical variables
  • analytical methods
  • statistical applications
309
Q

Describe selection of reference individuals

A
  • must be determined before data are collected
  • data should be collected from “normal,” healthy individuals
  • list of selection criteria must be established
  • another set of criteria that require attention is referred to as partitioning criteria
310
Q

What are preanalytical variables?

A

Include factors that affect the reference individual, specimen collection, and specimen handling
- diet
- fasting versus nonfasting
- drug therapies
- physical activity
- stress
- time
- body posture
- site preparation
- equipment
- technique
- transport
- storage
- clotting
- separation of serum or plasma
- preparation for analysis

311
Q

Desribe analytical methods

A
  • factors that affect analytical performance, including equipment, reagents, calibrators, and calculations, require control and documentation
  • quality control materials should be assayed throughout the reference interval study to monitor the analytical procedure
312
Q

Describe statistical applications

A
  • the reference interval may be described as the interval between the 2.5th (Lower reference limit) and 97.5th (upper reference limit) percentiles of a group of data obtained from a reference population
  • CLSI guidelines recommend:
    —> a minimum of 120 reference values be used
    —> reference interval be determined by the non parametric method
313
Q

Describe quality assurance

A
  • total quality management (TQM)
  • represent global issues
  • responsibility of everyone involved in the care of patients
314
Q

What are some essentials for quality assurance?

A
  • commitment
  • facilities
  • resources
  • competent staff
  • reliable procedures, methods and instrumentation
315
Q

Describe quality control

A
  • refers to procedures for monitoring and evaluating the quality of the analytical results and reports
  • purpose is the verify the stability and accuracy of calibration and testing systems
316
Q

Describe quality-control materials

A
  • best practices when selecting appropriate material for QCis to use a matrix that is similar to the test specimens
  • several factors to consider:
    —> the materials must be stable
    —> the materials must be available in aliquots or vials
    —> the materials can be analyzed periodically over a long span of time
    —> there is little vial-to-vial variation
    —>the concentration of analyte should be in the normal and abnormal ranges
317
Q

Describe target values

A
  • assayed QC material has target values are determined by the manufacturer
  • unassayed QC material has no predetermined target values: ranges must be determined by the laboratory
  • target values include the mean and standard deviation of the analyte for the particular control material
318
Q

Describe quality control limits

A
  • must call within the total allowable error of the method
  • must allow for successful completion of proficiency testing required by state and/or federal regulatory agencies
319
Q

Describe levy-Jennings control chart

A
  • show the difference between the observed values and the expected mean
  • created by calculating the mean concentration and up to +/- for a pool of QC material
  • used to monitor controls for determining id patient can be reported or not.
  • evaluation f QC data is critical for accurate test results
320
Q

What is a trend?

A

A pattern of data in which all of the QC values continue to increase or decrease over a period of time. (4 consecutive controls)

321
Q

What is a shift?

A

4 consecutive data that remain on one side of the mean for a period of time

322
Q

Describe Levy Jennings’ chart values

A
  • each time the control are run the value is placed on the Ley-Jenning chart
  • the values are expected to fall up or down around the mean
  • a value may fall outside the range 5% of the time or 1 out of 20
  • a value may fall above the mean 2.5% of the time or 1 out of 40 runs
  • a value may fall below the mean 2.5% of the time or 1 out of 40 runs
323
Q

What can power functions be used for?

A

1) evaluating the performance capabilities of individual control procedures
2) comparing the performance of different control procedures
3) designing a new procedure with improved performance characteristics.

324
Q

What is the 1(2)s Westgard rule?

A

-One control observation exceeding the mean +/- 2s
- this is a warning rule

325
Q

What is the 1(3)s Westgard rule?

A
  • one control observation exceeding the mean +/- 3s
  • sensitive to random error
326
Q

What is the 2(2)s Westgard rule?

A
  • two consecutive control observations exceeding the same mean plus 2s or mean minus 2s limit
  • sensitive to systematic error
327
Q

What is the R(4)s Westgard rule?

A
  • one observation exceeding the mean plus 2s and another exceeding the mean minus 2s within a run not between runs
  • sensitive to random error
328
Q

What is the 4(1)s Westgard rule?

A
  • four consecutive observations exceeding the mean plus 1s or the mean minus 1s
  • sensitive to systematic error
329
Q

What is the 10^x Westgard rule?

A
  • 10 consecutive control observations falling on one side of the mean (above or below)
  • sensitive to systematic error
330
Q

What is the 7T Westgard rule?

A
  • reject run whenever control measurements trend in the same direction (get progressively higher or lower)
331
Q

What are sources of random error when running quality control?

A
  • operator technique
  • use of non-reagent-grade water
  • incorrect reconstitution of control material
  • power supply
  • pipetting mistakes
  • automated pipette problems
  • air bubbles in tubing
332
Q

What are sources of systematic errors when running quality control?

A
  • improper alignment of sample or reagent pipettes
  • unstable incubator chambers
  • change of reagent lot
  • change in calibrator lot
  • deterioration of reagents in use
  • deterioration of control material while in use
  • evaporation of sample during analysis
  • dirty filter or gradual delaminating of monochromatic filter
  • change is test operator
  • recent calibration
  • deteriorating light source
  • incorrect handling of control material
333
Q

How would quality control problems be detected?

A
  • computers
    —> real-time review
    —> early detection of QC problems
    —> documentation of the QC process
  • patient results
    —>monitoring patient result, especially serial results on a single patient, Can alert the CLS to quality issues that require attention
334
Q

Describe remedy for Westgard rule violations

A
  • If QC results violate any Westgard rules, the laboratory must have a procedure that will resolve these violations
335
Q

What are the 3 options a CLS will have once patient results are generated?

A

1) accept the result
2) reject the result
3) modify the result

336
Q

What is Delta check?

A
  • procedure in which the CLS compares two consecutive laboratory results on a patient
337
Q

What are limit checks?

A
  • represent laboratory results that represent serious conditions relative to the patient
338
Q

What is auto verification?

A
  • verification and release of patient results using software-based algorithms with decision-making logic via the LIS
339
Q

Describe proficiency testing

A
  • also referred to as surveys
  • an example is quality control where in an agency or organization provides biological samples whose concentrations are unknown to the testing laboratory
  • included as a component of the quality assurance program
340
Q

What is the purpose of calibration?

A
  • to substantiate the continues accuracy of the test system throughout the laboratory reportable range of the test results for the test system
341
Q

What are standards?

A
  • highly purified substance of known composition
342
Q

What are control samples?

A
  • specimen that is similar to the patients blood with a known concentration of constituent
  • is included in every batch or run
  • it must be carried through the entire test procedure
  • it must be treated in the exact same way as the patient specimen
  • it is affected by any or all variables that affect the unknown (patient) specimen
343
Q

What is the objective in controlling reliability of the laboratory results? what are some ways of doing this?

A
  • reject results when there is evidence that more than the permitted amount of error has occurred

*run a control with every batch or run
* standard solutions
* control specimens
* duplicates

344
Q

Describe quality control material

A
  • chemistry controls are purchased, and the same lot number is used for about a year
  • when the lot number is scheduled to expire
  • new control data must be collected for about a month prior to expiration date
  • a new mean and 2 SD range must be established for the new controls
  • controls are reconstituted with water, mixed, and allowed to come completely into solution
  • date of reconstitution must be on the control bottle
  • controls must be run at room temperature
  • control must be run at room temperature
  • control must be kept closed and in the refrigerator between runs
345
Q

Describe collection of data in quality control

A
  • must mimic all conditions found when actually running the control during the year
    —> when controls are new and old
    —> when the instrument is clean and dirty
    —> by each and every tech who runs the instrument
  • must be run over a period of time
  • must use at least 30 data points but the larger the group of data the better the mean and range will be
346
Q

Describe implementation of new QC procedure

A
  • running of the “old” lot number of control to determine if patients results can be reported while collecting data for “new” lot number
347
Q

What are the three control values for each test performed?

A
  • abnormal high
  • normal
  • abnormal low
348
Q

What is the 95% confidence interval of the mean?

A

Statistics for acceptable range

349
Q

what do exchange filters remove?

A

Ions, which reduces the mineral content of water

350
Q

What is 1 inch in cm?

A

2.54 cm

351
Q

How many kg are in a lb?

A

2.2lbs

352
Q

How many quarts are in a liter?

A

1.06 qts

MLT Clinical Chemistry (7 decks)

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