M1 U3: Glassware, Equipment and Supplies Used in Clinical Chemistry Flashcards
Volumetric Flask
- class A quality
- calibrated to contain (TC) one specific amount or volume of liquid
- flasks label also indicated the nominal volume, tolerance, precision class and relevant manufacturing standard
- used to bring a given reagent to its final volume with the prescribed diluent
Erlenmeyer Flask
- aka titration or conical flask
- measuring, mixing, heating, but better suited for swirling solutions and can easily be held at the neck in one hand
- designed to hold different volumes rather than one exact amount
Beakers
- can be heated to much higher temperatures compared to plastic counterparts, higher clarity and content visibility and measuring
- graduated markings are accurate within 10%; not as precise as volumetric flasks or graduated cylinders
Graduated Cylinders
- more accurate and precise for measurement purposes than flasks and beakers but should not be used for volumetric analysis
- Plastic gc are impact resistant
- polyethylene gc are transparent
- polypropylene gc are chemically resistant
- Glass gc are chemically inert
- borosilicate gc greater resistance to thermal shock
Pipettes
- usually used for 20 mL or less; larger volumes are transferred or dispersed by automated pipetting devices or jar-style pipetting apparatus
- manual pipettes bulbs or pumps
- semi-automatic pipettes similar device built into it
- mouth pipetting, aspiration
Burettes
- used to dispense and measure a variable amount o a chemical solution in analytical chemistry at the same time
- stopcock valve
- Gas measuring burettes, stopcock is at the top of the glass tube
- Digital burettes, deliver at increasing accuracy and precision
Funnels
- Buscher and Hirsch funnels can remove fine particles from a liquid
- sintered glass frit is suggested for more demanding filtering applications
- Plastic, generally used for transferring powders
- polyethylene, aqueous solution transfers
- glass, inertness
- metal, won’t chip, break, corrode
Stirring Rod
- used to mix chemicals and liquids for reaction purposes
- glass with steel cores or in solid plastic
- chemically resistant, inert, and non-abrasive
- steel core, extra rigidity is required
- solid plastic, tapered end
- borosilicate, low thermal expansion values and feature flat ends
Glass Test Tubes
- most commonly and widely used lab glassware
- used to handle chemicals and allow you to observe the contents of the tube during the reaction
- 12 x 75 mm, containing samples (plasma or serum)
- 13 x 100 mm, containing protein-free filtrate
- 15 x 100 mm, containing distilled water or diluent for reagent preparation, whole blood for serum and protein-free filtrate preparation
Centrifuge Tubes
- used to contain liquids during centrifugation
- conical bottoms, help collect any solid or heavier parts of the sample being centrifuged
Cuvettes
- aka analytical cell or sample cell
- used to hold samples for spectroscopic measurement
- glass, suitable for visible region and routine UV work; greater transparency and accuracy of measurement
- quartz, UV far-infrared transmissions
- plastic, one use and do not require cleaning
- square, plane-parallel optical surfaces and a constant light path; advantage over round there is less error from the lens effect, orientation in the spectrophotometer, and refraction
- scratched surfaces should be discarded as they scatter light
Reagent Bottles
- excellent for storing powders and liquids
- tinted amber or red, protect light sensitive contents from UV light, visible light, and infrared radiation
- narrow mouths, better control while pouring
- wide mouths, easy filling or content retrieval
- caps or stoppers should be selected carefully, material or lining may interact negatively with the contents of the bottle
- plastic, glass, borosilicate glass, or soda lime glass
Thermometers
- utilization of laboratory refrigerators
- monitoring of temp of water baths, heating cells, and heating blocks
Liquid-in-glass thermometer
- measure between 20C and 400C
Calibration:
- calibrated against an NIST-certified or NIST-traceable thermometer
- SRM with calibration points (0, 25, 30, 37)
- calibrated against Gallium cell
Types:
i. Partial Immersion thermometer
ii. Total Immersion thermometer
iii. Surface Thermometer
Partial Immersion thermometer
used for measuring temps in units such as heating blocks or water baths
Total Immersion thermometer
used for refrigeration applications
Surface Thermometer
maybe needed to check temperatures in flat surfaces, such as an incubator or heating oven
Electronic Thermometer or Thermistor Probe
- small size and millisecond response time
- calibrated against SRM thermometer or the gallium melting point cell
- when calibrated against gallium cell, it can be used as reference for any type of thermometer
Digital Thermometer
- widely used
- overhauls and updates the traditional liquid-based thermometer
Syringes
- sometimes used for transfer of small volumes (less than 500 microliters) in blood gas analysis
- used in separation techniques such as chromatography or electrophoresis
Expected inaccuracies:
- < 5 microliter : 2% inaccuracy
- > 5 microliter : 1% inaccuracy
Rubber Bulb
- used with serological or volumetric pipettes
- silicone, natural or synthetic rubber
- allow safe, manual control of filling or discharging hazardous liquids
Parafilm/ Sealing Film
- thermoplastic, self-sealing film, it is ideal for the scientific laboratory
- stretchable, moldable, waterproof, and self-adhering, holds moisture loss to a minimum
- commonly used for sealing or protecting vessels as it offers excellent protection for the contents of tubes, flasks
Dessicants
- used to keep other chemicals from becoming hydrated
- most effective when placed inside a desiccator (closed and sealed containers)
- majority of which are hygroscopic
Hygroscopic
- substances that take up water on exposure to atmospheric conditions
- can remove moisture from the air as well as from other materials
Deliquescent substances
Substances capable of absorbing enough water from the atmosphere to cause dissolution
Hydrate
Compound with the associated water molecules
Anhydrous
When the water of crystallization is removed from the compound
Wash Bottles
used to supply precise and small quantities of various liquids
Test Tube Rack
help keep a lab organized and keeping test tubes up right
Disposable pipette tips
- designed to fit securely and tightly around a pipette barrel
- accuracy can be affected if not fit properly to the barrel
- poor seal, drawn-in air can escape and the correct volume of liquid is not aspirated
Spectrophotometer
- measures amount of photons (intensity of light) absorbed after it passes through sample solution
- amount of a known chemical substance (concentration) can also be determined by measure of intensity of light detected
Water bath
- incubate samples at constant temp
- temp may be controlled digitally or by dial
- water bath cycles on and off to ensure constancy of temp
Clinical centrifuge
- separation supernatant from a precipitate, two immiscible liquids and expelling of air
- centrifugal force is used to separate solid matter from a liquid suspension
- consists of a head or rotor, carriers, or shields that are attached to the vertical shaft of a motor or air compressor and enclosed in a metal covering
- some have a tachometer, indicates speed
Types of centrifuge
- according to designated area of placing
- according to rotor head/ speed
Types of centrifuge according to designated area of placing
- benchtop/ table-model
- floortop/ floor-model
- refrigerated centrifuge: -15C to -25C, permits centrifugation at higher speeds because the specimens are protected from the heat generated by the rotors of the centrifuge
Types of centrifuge according to rotor head/ speed
- horizontal-head centrifuge / swinging-bucket centrifuge
- angle-head centrifuge / fixed angle-head centrifuge
- microhematocrit centrifuge / microfuge
- cytocentrifuge
- ultracentrifuge
horizontal-head centrifuge / swinging-bucket centrifuge
- at rest: tubes are held at vertical position
- during centrifugation: horizontal
- 3000 rpm, 1700g
- no excessive heat production produced caused by friction between head and air
angle-head centrifuge / fixed angle-head centrifuge
- cups held at rigid position at fixed angle
- during centrifugation, particles travel along the side of the tube to form a sediment that packs against the bottom and side of the tube
microhematocrit centrifuge / microfuge
- suited for capillary tube
- used in hema lab for packing rbc
- speed 10,000 rpm - 15,000 rpm
cytocentrifuge
- uses a motor with very high torque and low inertia to spread monolayers of cells rapidly across a special slide for morphologic studies
ultracentrifuge
- high-speed generally used for research projects
- air driven ultracentrifuge available for clinical use 90,000 to 100,000 rpm max RCF of 178,000g
- often refrigerated
Centrifugal force
- expression of how many > force applied by centrifuge is compared to force of gravity
- expressed in relative centrifugal force (RCF) or g
Formula for centrifugal force
RCF = 1.118 x 10^-5 * r * (rpm)^2
Factors affecting Centrifugal force
- mass
- radius of centrifuge
- speed in revolutions per minute
General lab centrifuge operates at speeds of up to ___, generating RCF up to ____ time the force of gravity (g)
6000 rpm, 7000
Balances
Essential in producing high-quality reagents and standards
Classification of Balances
- Based on the number of pans (single or double)
- Based on whether they are mechanical or electronic
- Based on operating ranges
a. Precision balances: 2 microgram
b. Analytic balances: 0.001 g
c. Microbalances: 0.1 microgram
Analytic balances
- preparation of primary standard
- common model: mechanical analytic balance; aka substitution balance
- enclosed by sliding transparent doors, minimize environmental influences on pan movement
Electronic balances
- use an electromagnetic force to counterbalance the weighed sample’s mass
- fast response time
Classification of test weights (Conventional NIST Classification)
- Class S weights
- Class M weights
- Class S-1 weights
- Class P weights
- Class J weights
Classification of test weights (ASTM Classification)
- ASTM Class 1 weights
- ASTM Class 2 weights
- ASTM Class 3 weights
Class S weights
used for calibrating balances (prior to 1993)
Class M weights
Primary standard quality and used only to calibrate other weights
Class S-1 weights
greater tolerance than class S and used for routine analytical work
Class P weights
greater tolerance than S-1
Class J weights
intended for microanalytical work and range from 50 - 0.5 mg
ASTM Class 1 weights
- highest precision
- used to calibrate high-precision analytical balances weight range 0.01 mg to 0.1 mg
ASTM Class 2 weights
- equiv to former NBS S standard weights
- calibration weight range 0.001 to 0.01g
ASTM Class 3 weights
- equiv to former S-1 weights
- calibration weight range 0.01 to 0.1 g
Hot air sterilizer
- sterilizing instruments which can tolerate high temperature and need to remain in sterilized condition
- commonly for glassware and stainless steel
Pipet washers
thoroughly clean pipets quickly and easily
Laboratory refrigerators
cool or store samples or specimens for preservation
General washing routine procedure
- Soak in soapy or dilute bleach soln
- Wash using lab ware designed detergent
- Rinse 3 times (tap), 1 time (distilled)
- Dry in oven less than 140C
Acid Dichromate Method washing
- soln useful until green colour develops
- soak overnight and rinse with dilute ammonia
- rewash according to routine procedure
Nitric Acid (20%) washing
- soak 12-24 hrs
- wash according to routine procedure
Washing pipets (SI alkaline)
- rinse with 5% HCL or 5% HNO3
- wash routine procedure
Dirty pipets
- pipettes placed into cylinder containing a cleaning soln with tips up for 30 mins
- rinse with tap water using an automatic washer (pipette washer) for 1 to 2 hrs
- rinse with deionized or distilled water 2 - 3 times and dry oven
Blood clots
- soak 10% sodium hydroxide for 12-24 hrs
- routine wash
- dry micropipettes use acetone rinse (or acid chromate)
Metal ion determination
- 20% nitric acid 12-24 hrs
- rinse distilled 3-4 times water should be fresh with each rinsing step (or acid chromate)
Permanganate stains
- soak 50% HCl or mixture of 25% H2SO4 and 1% FeSO4
- rinse tap water
- wash
Grease
- soak in organic solvent or 50% KOH or Conrad 70 (manufactured by Harleco)
Iron determination
soak in HCL soln (1:2) or HNO3 soln (1:3) followed by thorough washing
Cleaning plasticware
- easy to clean because non-wettable surface
- wash with powder or liquid detergent
- distilled rinses
- check pH of final rinse water to check if all detergent has been removed from labware
- should be alkaline
- brush or abrasive shouldn’t be used
Drying glassware
- air-dry oven below 140C bottoms up
- occasionally rinse with water-miscible organic solvents (eg acetone) then expose to stream of air or nitrogen
Main purpose of regular maintenance ?
Ensure that all equipment required for production is operating at 100% efficiency all the time
What are the various procedures and routines ensuring that lab equipment is well maintained and cared for ?
- develop standard operating procedures
- prepare documentation on each specific equipment, repairs and maintenance undertaken
- outline preventive maintenance program
- train both technical and managerial staff on proper use and care
