Novel separation for the determination of cadmium by isotope dilution ICP-MS in samples containing high concentrations of molybdenum and tin

A four-step matrix reduction procedure, beginning with thiourea-based solid phase extraction, was developed for the determination of cadmium in difficult sample matrixes by inductively coupled plasma mass spectrometry. The separation scheme reduced the concentrations of tin and molybdenum, significant spectral interference sources for cadmium, from mg kg−1 levels to μg kg−1 and sub-μg kg−1 levels respectively, making possible interference-free measurement of cadmium and facilitating isotope dilution quantification. Cadmium recovery through the matrix reduction procedure was 78%. The effectiveness of the method was shown by application to NIST SRMs 1568a Rice Flour and 2703 Marine Sediment