1.0 Objective:
The purpose of this SOP is to
provide written procedure for Use, Calibration and maintenance of Micropipettes.
2.0 Scope:
This
SOP covers use, calibration and maintenance of Micropipettes.
3.0 Responsibility:
Jr. Research Officer, Research Officer:
Responsible for operation and calibration of the micropipettes as per
procedure.
Head of Department: Responsible
for calibration and maintenance, timely as per schedule.
QA Officer/QA Manager: Review the records and governing the document.
4.0 Procedure:
Use:
4.1 Attach the tip specific to the required
volume to the tip cone.
4.2 Hold the pipette in an upright
position while aspirating the liquid. The grippy should rest on the index
finger.
4.3 Before
beginning the actual pipetting work, fill and empty the tip 2-3 times with the solution
that is to be pipetted.
4.4 Depress the push button to the first stop.
4.5 Dip
the tip into the solution and slowly release the push button to the ready
position. Withdraw the tip from the liquid, touching it against the edge of the
container to remove excess liquid.
4.6 Deliver the liquid by gently pressing the push button to the first
stop. After a delay of about one second, continue to press the push button to
the second stop. This will empty the tip.
4.7 Release the push button to the ready position.
4.8 Release the tip in a waste receptacle
by pressing the tip ejector with the thumb.
Calibration:
4.9 The
following are required for calibration of the micropipettes.
4.10 Calibrated balance with the following
readable graduation for various volume range pipettes.
S.No
|
Volume Range
|
Readable graduation
|
1
|
Less than 100µl
|
0.01 mg
|
2
|
Above 100µl
|
0.1 mg
|
Calibrated
thermometer
Vessel
for weighing
Test
Liquid: Distilled water
Temperature
of Test Liquid: 15 to 30 °C
4.11 Place a calibrated thermometer in
the test liquid (distilled water) and record the temperature.
4.12
Pre-wet the tip for 3-5 times with the
distilled water.
4.13 Set the
pipette delivery volume at minimum range of the pipette.
4.14 Place the
weighing vessel on the pan of the balance and tare the weight.
4.15 Follow the
pipetting technique as described in section 4.0.
4.16 Record the measured weight (in mg) and tare
the weight on the pan.
4.17 Follow the
steps 4.15 to 4.16 for 10 pipettings.
4.18 Set the pipette
delivery volume at maximum range of the pipette.
4.19 Follow the
steps 4.15 to 4.16 for 10 pipettings.
4.20 Fixed volume
micropipette will be calibrated only at one volume.
5.0 Calculations:
5.1 Conversion
formula for measured weight in mg, to volume in microlitres
V = W/d
Where V: volume in µl
W: weight in mg
d: density of water in g/ml at the
calibration temperature.
5.2 Inaccuracy
(%) = (mean volume X 100/set volume)-100
5.3 Imprecision
(CV %) = 100 X SD/mean volume
CV: Co-efficient of variation
SD: Standard Deviation
Acceptance criteria as per ISO8655
Range Of Prepitte
|
Volume (µl)
|
Inaccuracy(%)
|
Imprecision(CV%)
Should Be less than
|
0.2-2 µl
|
0.2
|
±40.0
|
20.0
|
2
|
±4.0
|
2.0
|
|
0.5-10 µl
|
1
|
±12.0
|
8.0
|
10
|
±1.2
|
0.8
|
|
2-20 µl
|
2
|
±10.0
|
5.o
|
20
|
±1.0
|
0.5
|
|
5-50 µl
|
5
|
±10.0
|
4.0
|
50
|
±1.0
|
0.4
|
|
10-100 µl
|
10
|
±8.0
|
3.0
|
100
|
±0.8
|
0.3
|
|
20-200 µl
|
20
|
±8.0
|
3.0
|
200
|
±0.8
|
0.3
|
|
100-1000 µl
|
100
|
±8.0
|
3.0
|
1000
|
±0.8
|
0.3
|
|
200-1000 µl
|
200
|
±4.0
|
1.5
|
1000
|
±0.8
|
0.3
|
|
1-5 ml µl
|
1000
|
±4.0
|
1.5
|
5000
|
±0.8
|
0.3
|
|
2-10 ml µl
|
2000
|
±3.0
|
1.5
|
10000
|
±0.6
|
0.3
|
Calibration frequency:
6.1 Calibrate the
micropipettes once in three months (+ extended 10 days)
6.2 Calibrate the
pipette upon receipt from the supplier after repair (on receipt).
6.3 Recalibrate
the pipette on failure of calibration (Recalibration).
7.0
Precautions:
Take the following precautions when
using a micropipette:
7.1 NEVER rotate
the volume adjuster beyond the upper or lower range of the pipette.
7.2
NEVER invert or lay the micropipette down with a filled tip;
fluid can run back into the piston.
7.3 NEVER let the
plunger snap back after withdrawing or expelling fluid; this could damage the piston.
7.4 NEVER immerse
the barrel of the micropipette in fluid.
7.5 NEVER flame
the tip of the micropipette.
7.6 When not in use, keeping the
micropipette in its maximum volume range prolongs the life span of the spring.
8.0
Routine maintenance:
8.1
Clean the instrument with dry
cloth.
8.2 Clean
the electrode with clean and dry tissue paper.
9.0 Documentation:
9.1 Annexure
– 1 Density (g/ml) of water at different
temperature.
9.2 Annexure –2 Micropipette Calibration Format XXX/FRM/000
10.0 History of Revision:
Revision No.
|
Effective
Date
|
Revision
details
|
Reason for
revision
|
Annexure 1
Annexure 2
MICROPIPETTE CALIBRATION FORMAT
Pipette ID: Volume Range:
Date of calibration: Temperature of distilled water:
Density of water:
S.No.
|
Minimum
delivery volume
|
Maximum
delivery volume
|
||||
Set
Volume (µl)
|
Measured
Weight (mg)
|
Volume
(µl)
|
Set
Volume (µl)
|
Measured
Weight (mg)
|
Volume
(µl)
|
|
1
|
||||||
2
|
||||||
3
|
||||||
4
|
||||||
5
|
||||||
6
|
||||||
7
|
||||||
8
|
||||||
9
|
||||||
10
|
||||||
Mean Volume (µl)
|
Mean Volume (µl)
|
|||||
Inaccuracy (%)
|
Inaccuracy (%)
|
|||||
Standard Deviation (%)
|
Standard Deviation (%)
|
|||||
Imprecision (%)
|
Imprecision (%)
|
|||||
Balance Used (ID)
|
Thermometer
Used (ID)
|
||||
Result:
|
|||||
Calibrated
by
|
Signature
and Date
|
Calibration
due on
|
|||
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