Mathematical correction for polyatomic interferences in the speciation of chromium by liquid chromatography–inductively coupled plasma quadrupole mass spectrometry

A procedure for overcoming polyatomic interferences in liquid chromatography–quadrupole inductively coupled plasma mass spectrometry based on the mathematical correction point by point along the chromatogram is described. Correction factors, that are part of the elemental equations used for mathematical correction, were calculated from the height or the area of the peaks obtained after measurement of interference stock solutions by flow injection. Due to the sequential nature of quadrupole mass spectrometers, the selection of the acquisition parameters with respect to the peak width and the number of isotopes monitorised is critical. A sampling frequency which allows getting a minimum of 20 points per peak is recommended to avoid artifacts in the corrected profiles of the peaks. The effect of polyatomic interferences from carbon and chlorine on the determination and speciation of chromium by high performance size exclusion chromatography coupled to quadrupole inductively coupled plasma mass spectrometry in compost lixiviates is studied. Biased results of + 50% are successfully corrected by the proposed procedure.