Lab #1 - Micropipetting

What is accuracy?

How close a measured value is to the correct or expected value

What is precision?

How close repeated measurements are to one another

Measurements are tightly grouped but far from original value?

High precision, low accuracy

What is the range of a P20?

2-20uL (clear tip)

What is the range of a P200?

20-200uL (yellow tip)

What is the range of a P1000?

100-1000uL (blue tip)

What pipette would you use for a 12.4uL?

P20

What pipette would you use for a 150uL?

P200

What pipette would you use for 900uL?

P1000

Basic Micropipetting Procedure

1. Set volume

2. Attach appropriate tip

3. Press to first stop

4. Immerse tip

5. Slowly release to aspirate

6. Transfer

7. Press through first and second stops

8. Remove tip

9. Release plunger

What is the first stop used for?

To aspirate the selected volume during normal forward pipetting

What is the second stop used for?

To blow out any remaining liquid when dispensing

What should you check after aspirating?

Make sure there are no bubbles in the tip

Why to use new pipette tip between different samples?

To prevent cross contamination

Why shouldn’t you use a micropipette outside its volume range?

Can produce inaccurate volumes and affect calibration

Why shouldn’t you lay a filled micropipette horizontally?

Liquid can enter pipette body and damage it.

What wavelength was used to measure yellow #5?

422nm

How was the 10% yellow dye solution prepared?

100uL dye + 900uL water

How was the 5% solution prepared?

50uL dye + 950uL water

How was the 1% solution prepared?

10uL dye + 990uL water

How was the 0.5% solution prepared?

5uL + 995uL water

What happens to Yellow #5 absorbance as concentration increases?

Absorbance increases

If a 10% and 1% Yellow #5 sample are measured, which should have the greater absorbance?

The 10% sample

What does an R² value closer to 1 indicate?

The measured data fit the expected/regression relationship more closely.