Experiment 1
Use of Micropipettes: measuring volume accurately
Prior to your hands-on training, you should understand:
• The function of micropipettes in the laboratory
• Basic parts of micropipette
• What volumes are measured with P10, P100 and P1000 micropipettes
• How to read the volume indicator on a P10, P100 and P1000
I. Objective:
• Learn how to use micropipettes
II. Background:
Micropipettes are the standard laboratory equipment used to measure and transfer small
volumes of liquids. The liter is the metric volume standard, and one microliter (μl) is one
millionth of a liter. Inaccurate pipetting is a chief contributor to poor laboratory results.
Micropipettes are used for accurately transferring small volumes of liquid in the milliliter and
microliter range. You will use them throughout this semester and in advanced courses that
you take in the future. It is essential that you master their use if you are to be successful in
your experiments.
P10 0.5-10
P100 10-100
P10 100-1000
P1000
P10
1
P10 P100
P10 P10
P1000 P100 P10
P10 P10 P10
0
P10
0.2
P10
P1000
P10
P100
0
P10
P10
P10
2
Micropipette and Tip Guide
P-100 10-100
P10 P10
0
P10
100
P10
100-1000
P10
P-10
P10
P-100
P10
3
How to set volume:
The volume is set by turning the dial. When decreasing the volume, slowly turn the dial
clockwise to reach the required volume. Be careful not to overshoot.
When increasing the volume, slowly turn the dial anticlockwise to
reach the required volume. Be careful not to overshoot.
Operating the micropipette:
4
Operating the micropipette:
5
Experiment: Practice with Large-Volume Micropipette
This exercise will aid you to achieve accuracy and help you to be successful in your
Biochemical, Immunological, Nutritional, Microbiological as well as Molecular Biology
experiments for which a 100-1000µl micropipette is used. It is far easier to mis-measure when
using large-volume micropipettes. If the plunger is not released slowly, an air bubble may
form or solution may be drawn into the piston.
1. Use a permanent marker to label two 1.5 micro centrifuge tubes A and B.
2. Use the matrix below as a checklist while adding solutions to each tube.
Tube Sol. I Sol. II Sol. III Sol. IV
A 100µl 200 µl 150 µl 550 µl
B 150 µl 250 µl 350 µl 250 µl
3. Set the micropipette to add appropriate volumes of solutions I to tubes A and B.
4. Use a fresh tip to add the appropriate volume of Solution II on tubes A and B.
5. Use a fresh tip to add the appropriate volume of Solution III on tubes A and B.
6. Use a fresh tip to add the appropriate volume of Solution IV on tubes A and B.
7. Close the tops of the tubes.
8. Pool and mix the reagents by placing the tubes in a centrifuge and apply a short pulse of
several seconds. Make sure that the tubes are placed in a balanced configuration in the
microcentifuge rotor. Spinning tubes in an unbalanced position will damage the
microcentifuge rotor.
9. A total of 1,000µl of reactants was added to each tube.
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10. To check the accuracy of your measurements, set the micropipette to 1000µl and
carefully withdraw the solution from each tube.
a. Is the tip barely filled?
OR
b. Does a small volume of fluid remain in the tube?
OR
c. After withdrawing all fluid, is an air space left in the end of the tip?
If your measurements were inaccurate, repeat the exercise to obtain nearly perfect results.
