Determination of cadmium by inductively coupled plasma mass spectrometry-reduction of molybdenum oxide interferences by addition of acetonitrile Original Research Article

The determination of cadmium at trace and ultra trace levels is important due to its toxicity. Inductively coupled plasma mass spectrometry (ICP-MS) is a highly sensitive and rapid technique suitable for the analysis of cadmium. But when a quadrupole analyzer is used isobaric interferences due to oxide ions of molybdenum can pose a problem and lead to erroneous results. A method was developed to reduce the oxide interferences for the accurate determination of cadmium at ng/g levels in the presence of excess molybdenum. The addition of a little quantity of acetonitrile was shown to reduce the molybdenum oxide ions leading to accurate recoveries of cadmium values in the presence of molybdenum. The developed method was validated by determining the cadmium concentration in an SRM, NIST 1568a rice flour, and a sample, Algae 392, distributed by IAEA for inter laboratory comparison purposes which contain a cadmium concentration of 0.022±0.004 and 0.0179±0.0044 μg/g, respectively and a much larger molybdenum concentration. The concentrations obtained, 0.021±0.004 and 0.026±0.004 μg/g, respectively, by the developed method agreed very well with the certified values.