FEASIBILITY OF THE DIRECT ANALYSIS OF URINE BY INDUCTIVELY COUPLED ARGON PLASMA MASS-SPECTROMETRY FOR BIOLOGICAL MONITORING OF EXPOSURE TO METALS

Urine samples have been analysed for metals using inductively coupled plasma mass spectrometry (ICP-MS). The samples were simply diluted (1 + 9) with 2% v/v nitric acid and introduced into the ICP-MS system. Data for multi-element determinations were obtained by scanning the mass range from 2 to 256 u at a rate of 0.5 scans s-1 for 4 min. Under these conditions, the detection limits are less than 1 ng ml-1 for the original urine sample with linear ranges in excess of 1 × 104. The quantitative performance of the technique applied to real samples was comparable to that obtained from established methods for antimony, mercury and cadmium. The application of this approach to certain metals is restricted by the presence of a number of interferences in the range m/z = 10-80. The system was operated for an entire working day with no evidence of deterioration in the mass spectrometer interface and with a system stability of the order of 5% relative standard deviation. Within the limits described, this method provides a useful tool for monitoring a variety of metals in urine at the levels which might be of interest in a programme of biological monitoring of human exposure.