works on the principle of equivalence of the electric charge and amount of substance described by Faraday's law. It serves for the realisation and transfer of unit of amount of substance by primary certified reference materials

is based on maintaining sets of PRMs of gaseous mixtures of highly defined composition. After being prepared by mixing weighed amounts of highest purity gases or of another gaseous PRMs together mixture composition is validated by chemical analysis. It serves for providing traceability in measurements of gas mixtures composition.

is based on the absolute measurement of conductivity in an electrolytic cell with calculable value of the cell constant. The unit is further transferred by means of certified reference materials. The measurement range is 0.01 - 10 S.m^-1, the relative uncertainty is 0.05 %.

is based on the primary pH measurement using the hydrogen and Ag/AgCl electrodes in an electrolytic cell without liquid junction. The pH values are further transferred by primary certified reference materials. The measurement range is 1 - 12, the uncertainty is 0.002 - 0.005.

serves for the calibration of different types of air (gas) humidity meters at laboratory temperature in the dew point temperature range from -75°C to +20°C, and relative humidity 0 100% resp. The standard is based on the dew point measurement principle.