LAB GLASSWARE Flashcards
Tolerance and accuracy
Limits of error; nearness to the true value
Precision and reproducibility
Ability to repeatedly produce the same value
Capacity in terms of glassware
Volume the glassware will hold or deliver
Temperature in regards to glassware
Temp the glassware was calibrated and temp to be used at
What’s the average temperature for glassware to be calibrated at?
20c
Liquid ____ when warmed.
Expands
Liquid ____ when cooled.
“Contracts”
TC?
To contain
What does TO CONTAIN mean?
Holding a specific volume
TD?
To deliver
What does TO DELIVER mean?
Holding a bit more than what is stated; this is to deliver the stated amount
What is prepared in TC glassware?
Solutions
What are some examples of TC glassware?
Volumetric flasks
What glasswares are TD?
Pipettes and some graduated cylinders
Where should the meniscus be?
The lowest part of the meniscus should be ON the calibration mark.
What are volumetric flasks primarily used for?
Preparation of accurate solutions — reagents and controls
What are cylinders used for?
Prepare solutions that require less accuracy — ex. Cleaning solutions
Are cylinders TC or TD?
Both
What are examples of glassware that aren’t calibrated TC or TD—graduation marks are approximations?
Beakers, Erlenmeyer flasks, test tubes, and reagent bottles
Volumetric pipettes are ____ (TC/TD).
TD
Which is the most accurate pipette?
Volumetric
What are some examples of graduated/measuring pipettes?
Mohr and serological
What’s the difference between a Mohr and serological pipette?
Mohr pipettes aren’t calibrated at the tip while serological pipettes are.
Serological pipettes aren’t wiped with a tissue!
Mohr - you discard the liquid at the tip
Serological - you blow out the last drop
What’s the ranking of pipettes in terms of accuracy?
Volumetric
Mohr
Serological
Pasteur
What are serological pipettes used for?
Serial solutions; measuring thick liquids; procedures where accuracy doesn’t matter
What are semiautomatic pipettes used for?
The measuring of small volumes (1uL - 1000uL).
What are good techniques for using semiautomatic pipettes?
- pipette held vertically
- smooth depression and release of plunger
- depress plunger before inserting into sample
- when transferring to a receiving tube, don’t release plunger till you remove from receiving tube
What are examples of semiautomatic pipettes?
MLA pipettes, and Eppensorf/Hamilton pipettes
What’s the difference between a MLA pipette and an Eppendorf/Hamilton pipette?
The eppendorf/Hamilton pipette’s plunger has two stops
How do you proper usage of the two stops on an eppendorf/Hamilton pipette?
- first stop for picking up sample
- depress plunger to first stop when transferring to receiving tube, wait one second then depress to second stop
How do you maintain a MLA pipette?
- Clean and lubricate the piston every 3 months.
- apply thin coat of silicone to piston.
- replace seal if pipette doesn’t pick up or discharge samples
- clear nozzle with compressed air jet or fine wire if clogged
- calibrate
How often should calibration and quality control checks be done on eppendorf/Hamilton pipettes?
Every 6 months or after maintenance
What are some examples given for specialty pipettes?
Repeater, multi-tip, and digital
What are repeater pipettes?
Pipettes that draw up a large volume, and dispenses some into multiple tubes
What are multi-tip pipettes?
Pipettes that have many tips attached to one pipette to deliver the same volume into multiple sample cups at once
What are digital pipettes?
Pipettes that have digital volume displays
How do you check if glassware is physically clean?
Water will uniformly wet the surface of the glass
How do you check if glassware is chemically clean?
By measuring the pH of water added to the glassware
Or by adding dilute indicator to the surface of the glass
How many rinses with tap water do you need to do to manually clean glassware?
7-10
How many rinses do you need to do with distilled water when manually cleaning glassware?
3
How many cycles does the laboratory glassware washers have?
6
What are the six cycles the laboratory washer goes through?
- Pre-rinse
- Detergent wash
3, 4, 5. First, second, and third rinses
6. Distilled or deionized water rinse