(in Russian – ГОСТ 23463-79 Графит порошковый особой чистоты. Технические условия).

This standard applies to powdered artificial / synthetic graphite of special purity, used as a basis for the spectral analysis of various substances.

The mass fraction of particles up to 90 microns (micrometers) in powder graphite should be at least 90%, particles from 90 to 140 microns (micrometers) – not more than 10%.