[Field test for determination of mercury in cereals and cereal products]

By means of the method described, rapid semiquantitative mercury determinations may be performed without energy supply in cereals and cereal products. The mercury ions which are liberated by digestion with concentrated H2SO4 and KMnO4 are determined with the aid of a colorimetric method which is based on the formation of a coloured complex of mercury with di-beta-naphthyl-thiocarbazone. The method permits visual comparison of mercury concentrations ranging from 0.1 to 13 mug, revealing concentration differences up to 0,1 mug. The rate of recovery is 76%.