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 i nterferences disappear when a high-resolution magnetic sector mass spe ctrometer 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 instrum ent are shown. The instrument is a commercially available machine (Fin nigan MAT, Bremen, Germany) offering standard resolution settings of 3 00, 3000 and 7000 (M/DELTAM, 10% valley definition). With a resolution setting of 3000, V, Fe, Cu and Zn were determined in a second generat ion human serum reference material. Human serum diluted 4- to 8-fold w as measured. The results, expressed as concentrations (mug g-1) [stand ard 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 appro ximately 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 radiochemica l neutron activation value of 0.67 ng g-1, SD 0.05 ng g-1. For the det ermination of Ag using the low resolution (300) setting a limit of det ection (LOD) of 4.3 pg ml-1 in the solution was found. The instrumenta l LOD is 10-100 times lower and the experiments show that an investiga tion of blanks and methods of dealing with memory effects will be nece ssary before full use can be made of the sensitivity of high resolutio n ICP-MS.