DETERMINATION OF CHROMIUM IN URINE BY STABLE ISOTOPE-DILUTION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY USING LITHIUM BIS(TRIFLUOROETHYL)DITHIOCARBAMATE AS A CHELATING AGENT

An isotope dilution gas chromatography/mass spectrometry method using lithium bls(trifluoroethyl)dithiocarbamate as a chelating agent Is described for the determination of chromium in urine. A wet digestion procedure with HN03-H202 is used for oxidizing the organic matter associated with urine samples. The isotope ratios are measured by selected ion monitoring in a general-purpose mass spectrometer using a 10-m fused silica capillary column. Memory effect, in sequential analyses of samples with different isotope ratios, was evaluated by preparing a series of synthetic mixtures and was found to be negligible. The accuracy of the method was verified by quantitation of chromium in the NIST freeze-dried urine reference material, SRM-2670, with a recommended chromium concentration of 13 μg/L in the normal level and certified chromium concentration of 85 ± 6 μg/L in the elevated level. © 1990, American Chemical Society. All rights reserved.