SOP for Operation and Calibration of Micropipette

1.0 PURPOSE

To lay down the procedure for Operation and Calibration of Micropipette.

2.0 SCOPE

It is applicable to Microbiology Laboratory

3.0 RESPONSIBILITY

Microbiologist / Chemist

4.0 ACCOUNTABILITY

Head of Department

5.0 PROCEDURE

5.1 VOLUME SETTING

The volume can be changed continuously by rotating the setting of the ring.

5.2 PIPETTE TIPS

The pipette can be used only when a pipette tip is attached into which the liquid is aspirated.

5.3 ASPIRATING LIQUID

5.3.1 The liquid, which is to be aspirated, is taken from a suitable vessel.
5.3.2 Attach the tips to the pipette firmly
5.3.3 Immerse the pipette tips approximately 3 mm to 5 mm into the liquid or into suitable depth into the liquid.
5.3.4 Allow the control button to slide back slowly.
5.3.5 Pull the micropipette tips out of the liquid slowly.

5.4 DISPENSING LIQUID

5.4.1 Hold the tips at an angle against the inside wall of the tube / well/bottle/suitable vessel.
5.4.2 Press down the control button slowly to the first stop and wait until the liquid stops flowing.
5.4.3 Press down the control button to the second stroke until the tip is completely empty.
5.4.4 Hold down the control button and pull the tips up the inner wall of the tube.
5.4.5 Allow the control button to slide back slowly.

5.5 CALIBRATION

5.5.1 Calibration of micropipette should be done every 3 month with weight variation.
5.5.2 Different set of volumes should be taken and linearity should be performed.
5.5.3 Attach micropipette tips to micropipette. The desired volume is set and water shall be aspirated. Dispensed into dry beaker and weighed repeat for 10 times. The mean of the weights are converted into µl using the following formula:
Volume = Weight of water sample
              Density of Water (At 25°C)
5.5.4 The percentage variation can be calculated by using following formula.
Percentage variation = Actual weight – observed weight X 100
                                                   Actual weight
5.5.5 Perform the calibration by using the set volumes.
Related: Calibration of Glassware (Class A and Class B)

5.6 HANDLING, CARE AND MAINTENANCE

5.6.1 Do not lay down the pipette when a filled pipette tip is attached.
5.6.2 Avoid difference in temperature between pipettes and pipette tips as well as the liquid. as this may lead to incorrect volumes being dispensed.
5.6.3 Do not allow any liquid to enter into the pipette.
5.6.4 Do not clean the pipette with acetone or aggressive solutions.

6.0 ABBREVIATIONS

6.1 SOP - Standard operating procedure
6.2 Min. - Minute
6.3 °C - Degree Centigrade

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