TITLE: Determination of the accuracy of micropipettes for the biochemistry lab
AUTHORS: Chris Berndsen

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block">Basic protocol to help students use the laboratory micropipettes in the range of 1 to 1000 μL. </div></div>

[STEPS]
?. [Before calibration]
Fill a beaker with 20 mL of ddH2O.
20 mL
The volume does not have to be accurate.
?. [Before calibration]
Measure and record the temperature of the water.
?. [Before calibration]
Tare the balance with the weigh boat.
?. [Measuring liquid dispensing]
Set the volume of the pipette as shown in Step 4.1 to the appropriate volume for the measurement.
It is best to "dial down" to the desired volume, so you may need to go past your target volume and then dial back.
?. [Measuring liquid dispensing]
ABCD1micropipette rangelow volume (uL)middle volume (uL)high volume (uL)21 to 10 uL151032 to 20 uL2102041 to 100 uL150100520 to 200 uL201002006100 to 10001005001000
ABCD1micropipette rangelow volume (uL)middle volume (uL)high volume (uL)21 to 10 uL151032 to 20 uL2102041 to 100 uL150100520 to 200 uL201002006100 to 10001005001000
?. [Measuring liquid dispensing]
Put tip onto pipette by taking micropipette, placing the shaft into the desired tip and pushing while twisting slightly.
You do not need to hammer or slam the micropipettor into the tip to get it to stay.
Always use tips on micropipettors!
?. [Measuring liquid dispensing]
Depress the plunger on the micropipette to the first stop.
It is worth taking time to familiarize your self with the micropipette plunger positions if you have not used one before/recently. The first stop refers to the initial resistance of the plunger but is not fully depressed. The second stop is when the plunger is fully depressed. The up position is the default position.
?. [Measuring liquid dispensing]
Submerge the pipette tip in the water about 2 mm below the menicus for small volume micropipettes (
?. [Measuring liquid dispensing]
Allow the plunger to go to the up position. Depress the plunger to the first stop to eject the liquid, then allow the plunger to return to the up position. This is called "pre-rinsing".
The pre-rinse liquid can be ejected to waste as well if desired or to avoid contamination. In general, pre-rinsing should be down with each new tip or volume.
?. [Measuring liquid dispensing]
Remove pipette tip from water.
?. [Measuring liquid dispensing]
Eject water onto the weigh boat by depressing the plunger down to the second stop.
?. [Measuring liquid dispensing]
Remove tip from the liquid and then allow plunger to move to the up position.
?. [Measuring liquid dispensing]
Record the mass of the water.
?. [Measuring liquid dispensing]
Repeat steps 6 to 12, 5 times additional times and record the masses (6 total measurements).
?. [Measuring liquid dispensing]
Measure the temperature of the water to ensure it has not changed significantly during the measurements.
?. [Determining accuracy of the pipette]
Transfer your data into the calibration worksheet.
?. [Determining accuracy of the pipette]
Put the date, the name of your group, and the balance identity in the first row in the appropriate cells.
?. [Determining accuracy of the pipette]
Fill in the temperature and the density of water in row 2.
?. [Determining accuracy of the pipette]
In row 4, replace the text or fill in the cell next to pipette number for all three boxes.
If you are only doing one pipette, these will all be the same. If you are testing different pipettes, this information can be different.
?. [Determining accuracy of the pipette]
In rows 7 to 12 of column A, put in the volume in μL and in column B record the mass in milligrams.
1 mg is 0.001 g.
?. [Determining accuracy of the pipette]
Repeat step 15 and all sub-steps for other volumes.  Make note of any changes in accuracy across the pipette range. In step 15.4, you will use columns D/E, G/H, J/K, etc. to calculate the accuracy of the other volumes tested.
?. [Determining accuracy of the pipette]
Upload data to the appropriate space on the Open Science Framework and move onto the next pipette.