Patent ID: 7148068

Claim:
A method for determination of the concentration of trivalent chromium Cr(III) in a sample (in solution) comprising the steps of: dividing said sample into two sample parts; adding a first effective amount of perchloric acid to said second sample part, sufficient to induce an increase in the chromium atomic absorption signal due to Cr(III); measuring the chromium atomic absorption signals A 1 x and A 2 x from said first and second sample parts by flame atomic absorption spectrometry; dividing a standard (in solution) of known Cr(III) concentration into two standard parts; adding a second effective amount of perchloric acid to said second standard part, sufficient to induce an increase in the chromium atomic absorption signal due to Cr(III); measuring the chromium atomic absorption signals A 1 st and A 2 st from said first and second standard parts by flame atomic absorption spectrometry; determining the Cr(III) concentration in said sample by comparing the difference in measured signals for said sample to the measured difference for said standard.