Paints and varnishes — Determination of "soluble" metal content — Part 5: Determination of hexavalent chromium content of the pigment portion of the liquid paint or the paint in powder form — Diphenylcarbazide spectrophotometric method

The principle consists in formation of a coloured complex from hexavalent chromium and diphenylcarbazide solution. After addition of orthophosphoric acid and sulfuric acid, spectralphotometric easurement of the colour at a wavelength in the region of 540 nm. The method is applicable to coating materials having hexavalent chromium contents in the range of about 0,05 % (m/m) to 5 % (m/m). This method id the referee method in cases of dispute. This second edition cancels and replaces the ISO 3856/5-1980, of which it constitutes a through revision.