THE DETERMINATION OF COPPER, ZINC, CADMIUM AND LEAD IN URINE BY HIGH-RESOLUTION ICP-MS

High resolution ICP-MS was used to determine Cu, Zn, Cd and Pb in urin e. The effect of sample dilution, preparation method and choice of int ernal standard were assessed. Sample dilution (1 + 9) with In as the i nternal standard was found to coffer an acceptable compromise between analytical accuracy and sample throughput. A spectral resolution of 30 00 was used to separate Cu and Zn isotopes from interferences commonly found in biological matrices, while a resolution of 300, offering inc reased sensitivity and lower detection limits, was used for Cd and Pb. The accuracy and precision of the analytical method were evaluated us ing two Bio-Rad Lyphochek standard urines. The concentrations of Cu, Z n, Cd and Pb in Bio-Rad Level I reference urine were determined by ext ernal calibration and were found to agree to within 0-17% of recommend ed values (Cu 48, Zn 710, Cd 6.5 and Pb 14.3 ng g(-1)). Closer agreeme nt of 0-7% was found for Bio-Rad Level 2 reference urine (Cu 63, Zn 10 57, Cd 12.3 and Pb 69 ng g(-1)). Forty-two urine samples from seven wo rkers occupationally exposed to Cd were analysed and the results were compared with those obtained from 11 samples collected from four non-e xposed volunteers. Similar average concentrations of Cu and Zn were fo und in both groups when the results were normalised to creatinine leve ls. Workers exposed to Cd were found to have an average urine Cd conce ntration elevated approximately 7-8-fold over that measured for the co ntrol group (about 2.2 compared with about 0.3 ng g(-1), or 1.7 and 0. 2 mu g per gram of creatinine when normalised). Urinary levels of Pb w ere slightly increased in the cadmium exposed workers (about 6 compare d with about 4 ng g(-1)).