The United States Pharmacopoeia states :

"… The pharmacopoeial tests and assays require balances that vary incapacity, sensitivity and reproducibility. Unless otherwise specified, when substances are to be "accurately weighed" for assay the weighing is to be performed with a weighing device whose measurement uncertainty (random plus systematic error) does not exceed 0.1% of the reading. Measurement uncertainty is satisfactory if three times the standard deviation of not less than ten replicate weighings divided by the amount weighed does not exceed 0.001…"

To give you a rough estimate of the Minimum Weight of a particular balance it is possible use the following calculation :
Repeatability (standard deviation) of the balance x 3000

The repeatability figure will be quoted on the technical sheet which can be downloaded from our web site or by contacting our office on 01865 750375

Note :
The above calculation is only intended to give you an estimate for the minimum weight of a balance. A correct minimum sample weight can only be established at the customer’s premises, where the balance has been installed in the place of use and carried out by a qualified person.

For more information contact European Instruments on 01865 750375 and download our technical leaflet :