This is what we do in my lab (copied from the SOP). Hope it helps!

1. Record the temperature of the lab, using the thermometer situated next to the balance.

2. For volumes less than 200無 use a 1.5mL eppendorf as the receptacle for weighing, with a starting volume of 500無.

For volumes equal to and greater than 1000無 a 10mL falcon tube must be used, with a starting volume of 4mL.

For volume less than 30無 a 200無 PCR reaction vial should be used, with a starting volume of 50無.

3. Pipette the starting volume as listed above and seal the receptacle.

4. Place the sealed receptacle on the balance and tare the balance.

5. Remove the receptacle from the balance, pipette the test volume into the receptacle, then read and record the weight.

6. Repeat steps 3 and 4 above until 5 individual measurements are obtained.

7. The % accuracy can be worked out by the following:

(Mean value obtained/volume measured *100)-100 = X%.

For example: using a P1000 pipette at the bottom range of 200痞.

Mean value of (200.8/200 *100)-100 = 0.4%

8. The percentage precision can be calculated as follows:

(Standard deviation of measurements/mean value obtained)*100 = Y%

For example: using a P1000 pipette at the bottom range of 200痞.

Mean value of (21/200.8 *100) = 10.45%