ISO 2717:1973

Applicable to the determination of contents exceeding 1 mg/kg. The principle bases on evaporation of the test portion, dissolution in hydrochloric acid and reduction by hydroxylammonium chloride. Formation of complexes of interferring elements with ammonium citrate and potassium cyanide. Extraction of the lead at a pH of between 8.5 and 10 by a solution of dithizone in chloroform. Elimination of excess dithizone by an ammoniacal solution of potassium cyanide. Photometric measurement in chloroform solution at a wavelength of about 520 nm. Has also been approved by the IUPAC.