NEW HIGH-RESOLUTION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY TECHNOLOGY APPLIED FOR THE DETERMINATION OF V, FE, CU, ZN AND AG IN HUMAN SERUM

Spectral interferences are a limiting factor in quadrupole inductively coupled plasma mass spectrometry (quadropole ICP-MS). Most of these interferences disappear when a high-resolution magnetic sector mass spectrometer is coupled to the ICP ion source. In this paper, results of the first analyses with a new type of a high resolution ICP-MS instrument are shown. The instrument is a commercially available machine (Finnigan MAT, Bremen, Germany) offering standard resolution settings of 300, 3000 and 7000 (M/DELTAM, 10% valley definition). With a resolution setting of 3000, V, Fe, Cu and Zn were determined in a second generation human serum reference material. Human serum diluted 4- to 8-fold was measured. The results, expressed as concentrations (mug g-1) [standard deviation (SD) in parentheses] in the freeze dried material for Fe, 23.6 (0.8); Cu, 10.7 (0.2); and Zn, 8.2 (0.8) are in good agreement with the certified values. The very low V content is not certified. In the high-resolution spectrum the V peak was measured next to an approximately 1000 times higher Cl35O16 peak and a concentration of 0.83 ng g-1, SD 0.09 ng g-1 was found, which confirms an earlier radiochemical neutron activation value of 0.67 ng g-1, SD 0.05 ng g-1. For the determination of Ag using the low resolution (300) setting a limit of detection (LOD) of 4.3 pg ml-1 in the solution was found. The instrumental LOD is 10-100 times lower and the experiments show that an investigation of blanks and methods of dealing with memory effects will be necessary before full use can be made of the sensitivity of high resolution ICP-MS.