Trace element analysis in CRM of plant origin by inductively coupled plasma mass spectrometry

Three CRMs of plant origin (SRM 1515 Apple Leaves, SRM 1570a Trace Elements in Spinach Leaves, and SRM 1575 Pine Needles) were used for analytical quality assurance of Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, and Pb determination by ICP-MS. The samples were decomposed using microwave assisted pressurized digestion by HNO3 and HNO3 + H2O2 mixture and temperature programmed dry ashing. Concentrations of elements in samples were evaluated by external calibration. All samples, blanks, and standards were spiked to 100 mu g/L concentration of In and Bi as internal standards. During the measurement, signals of Cr-52, Cr-53, Fe-54, Mn-55, Co-59, Ni-60, Ni-62, Cu-63, Cu-65, Zn-66, Mo-95, Cd-111, Cd-112, In-115, Pb-206, Pb-207, Pb-208 and Bi-209 were monitored. Results of Pb, Cd, Cu, Zn, Mo and Co determination were in good agreement with certified values. In order to obtain accurate results for As at low levels, it was necessary to mathematically correct the analytical signal. This correction effectively eliminates the influence of interfering ArCl+ ions. For Cr analysis it is advisable to use as powerful oxidizing conditions during sample decomposition as possible.