Lab 2- Pipetting

Question 1

Purpose of pipettes

Answer 1

Measure and transfer small amounts of liquid

Question 2

Types of pipettes

Answer 2

Pasteur pipettes
Transfer pipettes
Serological pipettes
Analytical/micro- pipettes

Question 3

Pasteur pipettes

Answer 3

Reusable
Fragile
very low accuracy and precision
1-2 mL

Question 4

Transfer pipettes

Answer 4

Single use
Disposable
Soft plastic
Low accuracy and precision
1-5 mL

Question 5

Serological pipettes

Answer 5

Single use
Hard plastic
Sterile
Graduated
1-50 mL
Low to mid accuracy and precision

Question 6

Sizes of analytical pipettes

Answer 6

P10- 0.5-10 uL (white/clear tips)
P20- 2-20 uL (yellow tips)
P200- 20-200 uL (yellow tips)
P1000- 1000 uL (blue tips)

Question 7

Types of analytical pipettes

Answer 7

Positive displacement- Piston in direct contact w/ liquid. For viscous and volatile solutions
Air displacement- Certain amount of air b/n piston and solution. General use

Question 8

Steps for using air displacement pipettes

Answer 8

1. Change amount using vol adjustment knob
2. Push to first stop to displace are = to amount
3. Insert about 2 mm into liquid. Slowly release button and ensure the tip remains submerged. Pause to ensure it has fully aspirated. The vacuum equilises, drawing up liquid
4. Push button to increase pressure in tip and expel liquid. Push to 2nd stop to expel all liquid. Take out of liquid before releasing button

Question 9

Types of pipetting aids

Answer 9

Bulb- Aspirates solution in serological pipettes by displacing air. Easily contaminated, difficult to sterilise
Motorised aid- Increases reproducibility, precision, efficiency. Battery operated pump. Filter. Can be sterilised. Expensive