1. Intro to Chemistry Flashcards
Identify methods used to purify water and which substances they target to reduce. (6)
- prefiltration —initially traps particulates
- distillation —liquid boiled, vaporized, and condensed for purification
- reverse osmosis —water forced through semipermeable membrane; removes particulates, organics, bacteria, ionized and dissolved materials; does not remove gases
- deionization — water passes through insoluble resin polymers; removes some or all ions; does not remove organics
- carbon filters —activated charcoal removes organics
- particulate filters —bacteria
List items that should be monitored during the water-purification process.
at minimum —resistivity and bacteria
List the criteria for Clinical Laboratory Reagent Water (CLRW). (5)
- resistivity > 10 MΩ x cm at 25°
- CFU < 10/mL
- total organic carbon < 500 ppb
- Silicates < 0.05 mg/L
- water passed through 0.22 𝜇m filter for particulates
Distinguish the differences between Type A and Type B glassware.
A —more accurate; must be of certified accuracy
B —twice the durability, not as accurate; used in student labs
Assessing, setting, or correcting a device usually by comparing or adjusting it to match or conform to a reliable, known, and unvarying measure
calibration
performed after calibration
QC
resistivity
Electrical resistance in ohms measured between opposite faces of a 1.00-cm cube of an aqueous solution at a specified temperature
describe culturing water
allow to run for 1 min
aliquoted and plated
CFUs are determined
water for some chemical tests where CLRW is not adequate
special reagent water (SRW)
CLRW
clinical laboratory reagent water
types of reagent water, purification, use
- type I —filtered, distilled, deionized multiple times —trace metal, iron, enzymes analyses
- type II —double distilled —reagents, QC, standards
- type III —washing glassware
least pure chemical grades
Practical
Technical
Commercial
ACS chemical grades
Analytical grade
Reagent grade
Ultrapure:
Spectrograde
Nanograde
HPLC grade
organization
Atomic weight standard (grade A)
Ultimate standard (grade B)
Primary standard (grade C)
Working standard (grade D)
Secondary substances (grade E)
International Union for Pure and Applied Chemistry (I U P A C)
Provides standard reference materials (SRMs) in solid, liquid, or gaseous form
National Institute of Standard and Testing (NIST)
impossible in clinical chemistry (versus analytical)
knowing the exact composition of the material
primary standard
Highly purified chemical that can be measured directly to produce a substance of exact known concentration and purity.
Assigned a value after careful analysis. Used to verify calibration or accuracy/bias. Used in clinical chemistry.
Standard Reference Materials (SRMs)
advantages of reagents coming in kits
- less human error/variability
- less time consuming
- less danger to techs (carcinogens)
- less storage space
types of glassware
- borosilicate
- corex
- low actinic
describe borosilicate glassware
- high degree of thermal resistance
- damaged by highly alkaline chemicals
- should not be heated
describe corex glassware
- strengthened chemically rather than thermally
- 6 times stronger than borosilicate
- resists clouding and scratching
describe low actinic glassware
- amber or red color protects light sensitive substances
- high thermal resistance
- used to contain reagents, control materials, calibrators
4 types of plasticware
- polypropylene
- polyethylene
- polycarbonate
- polystyrene
May be flexible or rigid
Chemically resistant
Can be autoclaved
polypropylene
Test tubes, bottles, graduated tubes, stoppers, disposable transfer pipettes, volumetric pipettes, and test-tube racks
May bind or absorb proteins, dyes, stains, and picric acid
polyethylene
Used in tubes for centrifugation, graduated cylinders, and flasks.
Broad temperature range: -100 to +160°C.
Verty strong plastic, but not suitable for strong acids, bases, and oxidizing agents
polycarbonate
Rigid, clear type of plastic
Should not be autoclaved
Used in capped graduated tubes and test tubes
Will crack and splinter when crushed
polystyrene
Almost chemically inert
Suitable for use at temperatures ranging from −270 to +255°C
Resistant to a wide range of chemical classes
Teflon
2 classes of pipettes
- volumetric (transfer)
- measuring
TD
to deliver
calibrated to deliver a known amount of liquid
Bulb is closer to delivery tip
Accurate for viscous samples such as blood or serum
Ostwald-Folin pipette
Does not have graduations all the way to the tip
Will have fluid remaining in the tip once dispersed
Mohr pipette
Glass disposable pipette with a long skinny tip
Used with a blub (not disposable)
Pasteur pipettes
air displacement vs positive displacement
air — Uses a piston device to facilitate aspiration and ejection of liquids
positive —Uses a capillary tip made of glass or plastic to transfer liquids
methods of pipette calibration
- gravimetric
- Commercial photometric pipette-calibration products,
- Calibration-service providers
- Pipette Tracker
- VC-100® Acid-Base Titration Pipet Verification System
- PC S® Pipette Calibration System
weight
a function of mass under the influence of gravity
equal to mass multiplied by gravity
4 types of balances
Unequal-arm substitution balances
Magnetic force restoration balance
Top-loading balances
Electronic balances
Operates on the principal of removing weights
unequal-arm substitution balance
Operatves on the force required to put the balance back into equilibrium
magnetic force-restoration balance
Operates on electromagnetic force compensation
electronic balance
Damping or releasing the pan is accomplished by magnetism
Top-loading balance
Single pan enclosed by sliding transparent doors
analytic balance
calibration materials for balances
NIST class 1 weights —Available up to 250 mg
Class 2 balances —May be in excess of 1000 grams (g)
balance capacity
Maximum load one can weigh
balance accuracy
Closeness of the agreement between the measured result and the true value
balance linearity
Ability of a balance to follow the linear relationship between load and the displayed value
balance readability
Smallest increment of weight that can be read on the display
balance repeatability
Ability of a balance to produce the same result for repeated weighing of the same load under the identical measurement conditions
main 3 centrifuge components
Motor.
Drive shaft.
Rotor assembly.
Centrifuge motors use ————– to facilitate creation of electromagnetic fields that ultimately make the drive shaft turn.
carbon brushes
Method of comparing the force generated by various centrifuges on the basis of their speeds of rotation and distances from the center of rotation
relative centrifugal force (RCF)
RCF empirical factor
1.118 x 10^-5
RCF equation
(1.118 x 10^-5)(r)(rpm)^2 = RCF
5 types of centrifuges
Swinging-bucket rotor
Fixed-angle rotor
Air-driven ultracentrifuge
Ultracentrifuge
Refrigerated
Describe swing-bucket centrifuge
- used to separate cells from serum
- RCF is 1000-1200 x g
- 5-10 min centrifuge times
- allows tubes to assume horizontal position
Describe fixed-angle centrifuges
- tubes centrifuged at 25-52°
- faster spin
- used for STAT samples
Describe air-driven centrifuges
- Functions by directing compressed air onto grooves that are etched into the outer surface of the fixed-angle rotor
- used to remove lipid particles from lipemic specimens
Describe ultracentrifuge
- big
- can be around 100,000 rpms
- used to fractionate lipoproteins, perform drug-binding assays, prepare tissue for hormone receptor assays
2 types of water baths
circulating
noncirculating
1:1000 dilution of ——– can prevent bacterial growth in a water bath
thimerosal
define mixing
Operation intended to form a homogeneous mass or create a uniform homogeneous system
C to F
Transducer that converts changes in temperature (heat) to resistance
Thermistor
Sensor that consists of two dissimilar metals joined together at one end
Used to take temp quickly
Thermocouple
common dye in mercury-free thermometers
organic red spirit
thermometers should be verified at —- or —– intervals
6 month or 12 month
metric prefixes
density
Amount of matter (weight) per unit volume of substance
specific gravity
Method of measuring density
assay by weight
Represents the purity of the solute contained in the solution
Equal to the number of gram equivalents of solute per liter of solution
normality
% w/v
number of parts of solute in 100 parts solution
% = g solute/100 mL solution
salt molecules that can combine with water
hydrates
dilution
Represents the ratio of concentrated or stock material to the total final volume of a solution and consists of the volume or weight of the concentrate plus the volume of the diluent, with the concentration units remaining the same.
dilution factor
Ratio of concentrated or stock solution to the total solution volume
analytical balance range
0.01 mg to 160 g
