The standard applies to all types of wastewater with a lead content of at least 0.3 mg/l. The determination is interfered with by bis uth. Notes 1. Interference by metals that form dithizonates, with the exception of bis uth, is eliminated by the addition of potassium cyanide. 2. Interference due to iron is removed by adding tartaric acid. 3. Oxidation of the dithizonate is prevented by adding sulfite.
NEN 3235 7.5-1978 history
1978NEN 3235 7.5-1978 Test methods for waste water. Photometric determination of lead content