Addition of tertiary amines in the semiquantitative, multi-element inductively coupled plasma mass spectrometric analysis of biological materials

A semiquantitative inductively coupled plasma mass spectrometric (ICP-MS) analysis protocol for biological materials was developed to include water-soluble tertiary amines with microwave heated sample preparation. Certified reference materials digested with HNO3, H2O2 and HF required addition of H3BO3 and a solution of tertiary amines (CFA-C reagent) to dissolve insoluble fluorides and neutralize free fluorides. Commercial semiquantitative analysis software that evaluates the entire mit range and includes preprogrammed corrections for spectroscopic interferences was applied to investigate matrix interferences resulting from 10% tertiary amines and-chlorides (added as 1% HCl). Measurement parameters including m/z range, spectrometer sensitivity and number of elements in the external calibration were evaluated The accuracy of the semiquantitative analysis improved when the standard solution was matrix matched; interference-free isotopes were selected for some elements instead of scanning the whole mit range, and additional elements with m/z values of under 80 were included for updating the instrument pre-calibration response factor. This semiquantitative analysis approach can be applied successfully for the multi-element analysis of biological materials when optimum instrumental conditions are employed. Thirty-eight elements were determined in six certified reference materials and food samples with a precision of 1-20% and accuracy of 1-50%. The determinations of Al, K, Na and Si were unreliable.