Mass standards below a milligram
Scientists at the National Physical Laboratory are developing small mass standards with values below a milligram.
NPL is developing small mass standards to extend its measurement capability to sub milligram masses (Figure 1). This research supports the provision of mass calibrations for low force measurements. Pharmaceutical companies are also developing drugs with smaller quantities of active components leading to a need for traceable mass measurements below a milligram.
Small mass standards are conventionally manufactured out of metal foil or wire. This limits the minimum mass of the standard to about 100 µg, any smaller and the masses become difficult to handle. Particulates are increasingly being manufactured with uniform size and shape and hence should possess the same mass (Figure 2). This gives the opportunity to extend the mass scale below 100 µg and the potential to provide traceable mass measurements at the nanogram level.