INTERNATIONALSTANDARD ISO ISO11212-2:1997(E) Starch and derived products -- Heavy metals content -- Part 2: Determination of mercury content by atomic absorption spectrometry Scope This part of ISo11212 specifies a method for the determination of the mercury content of starch, including derivativesand by-products,byatomic absorption spectrometry with cold-vapourgeneration. The cold-vapour generators currently available use very different techniques; it is thus impossible to propose a should therefore optimize the conditions of use of his/her own apparatus on the basis of general or particular instructions. 2 Definition Forthepurposes of this part ofIsO11212,thefollowingdefinition applies. 2.1 mercury content: Quantity of mercury determined in accordance with the conditions specified in this method and expressedasmercury (Hg),inmicrogramsperkilogramoftheproductasreceived. 3Principle Wet digestion of the organic matrix.Reduction of mercury (Hg2+) to metallic mercury by hydrogen resulting from the ofgas anddeterminationof monoatomicmercuryvapourbyatomicabsorption spectrometryin aquartz cell. Measurement of the absorbance at a wavelength of 253,7 nm. Determination of the concentration of mercury in the sample by means of a calibration curve. 4 Reagents Use only reagents of recognized analytical grade and distilled water or water of equivalent purity. 4.1 Nitric acid (p20 = 1,38 g/ml). 4.2 Hydrogen peroxide, 30 % (V/M) solution.