DIN EN 16159:2012-04

DIN EN 16159 specifies a method for the determination of selenium in animal feeding stuffs by hydride generation atomic absorption spectrometry (HGAAS) after microwave pressure digestion. The method was successfully tested by an inter-laboratory study of CEN/TC 327/WG 4 in the range of 0,25 mg/kg to 74 mg/kg. The limit of quantification is 0,5 µg/l of the test solution which corresponds to the calibration standard 2. Using a test portion of 0,5 g and a volume of the test solution of 25 ml after pressure digestion the limit of quantification is calculated as 0,125 mg/kg in the feed material. Selenium is determined in the test solution by hydride generation atomic absorption spectrometry (fluorescence hydride generation atomic absorption) after microwave pressure digestion and a pre-reduction step. The homogenised feeding stuff test sample is digested by nitric acid and hydrogen peroxide under pressure and high temperatures in a microwave-heated pressure digestion system. Selenium ions of the test solution are reduced with hydrochloric acid to selenium (IV) and converted to selenium hydride by sodium borohydride. This selenium hydride is transferred by a gas stream to a heated measurement cell and decomposed. The absorption at the selenium line at 196,0 nm corresponds to the amount of selenium. The European Standard has been prepared by CEN/TC 327 "Animal feeding stuffs - Methods of sampling and analysis", the secretariat of which is held by NEN (Netherlands). DIN collaboration for the field of responsibility of CEN/TC 327 is performed through national Mirror Committee, Working Committee NA 057-03-03 AA "Futtermittel" ("Animal feeding stuffs") at NAL.