SOP for Calibration of Micropipettes

1.0 OBJECTIVE

To lay down a procedure is to provide guidelines for calibration of micropipettes.

2.0 SCOPE

This procedure is applicable for micropipettes which are used for various microbiological testing of Quality Control Department.

3.0 RESPONSIBILITY

Microbiologist

4.0 ACCOUNTABILITY

Head – QA & QC

5.0 PROCEDURE

5.1 Volume Setting

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

5.2 Aspirating Liquid

5.2.1 The liquid, which is to be aspirated, is taken from a suitable vessel.
5.2.2 Attach the tips to the pipette firmly
5.2.3 Immerse the pipette tips approximately 3 mm to 5 mm into the liquid or suitable depth into the liquid.
5.2.4 Allow the control button to slide back slowly.
5.2.5 Pull the micropipette tips out of the liquid slowly.

5.3 Dispensing Liquid

5.3.1 Hold the tips at an angle against the inside wall of the tube/ well/ bottle/ suitable vessel.
5.3.2 Press down the control button slowly to the first stop and wait until the liquid stops flowing
5.3.3 Press down the control button to the second stroke until the tip is completely empty.
5.3.4 Hold down the control button and pull the tips up the inner wall of the tube.
5.3.5 Allow the control button to slide back slowly.
Related: Calibration of Volumetric Glassware used in Pharmaceuticals

5.4 Calibration

5.4.1 Calibrate the micropipettes in a vibration-free room at a constant temperature of water between 20 to 25°C.
5.4.2 Calibrate the Micropipettes as per given in table -I.
5.4.3 First determine the density factor of water and then set the desired volume using the volume-setting knob.
5.4.4 Carefully fit tip into tip cone and flush with distilled water by pipetting the adjusted volume at least 3 – 4 times.
5.4.5 Carefully aspirate the liquid and pipette the sucked volume of distilled water into a tarred volumetric flask.
5.4.6 Repeat at least ten times and record the result.
5.4.7 Calculate the pipette volume as per following formula is given below
Volume = Weight of water
Specific gravity of water (at 25°C.)
5.4.8 The percent variation can be calculated as formula given below:
% variation = 100 x actual weight-observed weight
Specific gravity of water (at 25°C.)
5.5 Precautions: Use the analytical balance with a readability of 0.1 mg.
5.6 Frequency: Quarterly
Table-I


5.7 Limits/ Acceptance Criteria: RSD of Net volume of sample NMT 1%.

6.0 ABBREVIATION

SOP: Standard Operating Procedure
QA: Quality Assurance
QC: Quality Control

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