USP <1251> - Weighing on an Analytical Balance

What it says

This chapter provides guidance on weighing with an analytical balance, covering the choice of balance, its location and installation, calibration, qualification, routine performance checks, and good weighing technique. It addresses environmental effects such as drafts, vibration, temperature and static, and the minimum weight below which results are not reliable.

Paraphrased for plain-language clarity. Always verify against the current published regulation text.

What it means in practice

• Weighing is the basis for many quantitative results, so errors here carry through to everything downstream.
• The minimum weight matters, since small amounts weighed on a balance not suited to them can give unreliable results.
• Daily or pre-use checks with calibrated weights give routine assurance between calibrations.

What inspectors look for

• Whether balances are calibrated and checked as procedures require.
• Whether samples are weighed above the minimum weight for the balance.
• Whether balances are located and maintained so as to avoid environmental effects.

Related regulations