Certification of the contents of the chromium(III) and chromium(VI) species and total chromium in a lyophilised solution (CRM 544)†

Abstract

The preparation is described of a batch of 1100 vials containing a lyophilised solution, with Cr^VI and Cr^III contents as in natural or tap water and a total Cr content <50 µg l^–1 following the European Community Directive 80/778/EEC, L229/20, D48 on the quality of drinking water. The homogeneity and stability studies and the analytical work performed for the certification of the contents of the Cr^III and Cr^VI species and the total Cr content are also described. The paper contains all the results and gives the methods used to certify the measured concentrations of Cr^VI (22.79 µg l^–1), Cr^III (26.77 µg l^–1) and total Cr (49.34 µg l^–1) after reconstitution in 20 ml. A brief description of the preliminary feasibility study is also given.