Calibrate an analytical balance before a USP weigh

Practice the USP <41> / <1251> use-check order. Sample is not weighed until the check weight has passed, the result is recorded, and the sample is at or above the minimum weight.

1. Confirm the balance is level.
2. Close the draft shield.
3. Run the internal calibration if the SOP requires it.
4. Handle the assigned check weight with tweezers or gloves.
5. Weigh the assigned external check weight.
6. Record the as-found value against the tolerance.
7. Do not use the balance if the check fails; tag it out.
8. Confirm the sample mass is at or above the USP minimum weight.
9. Weigh the sample only after a passing check.
10. Return the check weight to its case.
11. Log the weigh.