Determination of chromium in water and urine by reaction cell inductively coupled plasma mass spectrometry

An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with a dynamic reaction cell (DRC) was used for the determination of chromium in water and urine samples. The effect of the operating conditions of the DRC system was studied to get the best signal-to-noise ratio. The potentially interfering (ArC+)-Ar-40-C-12, (ClOH+)-Cl-35-O-16, (SO)-S-34-O-18, (ArCH+)-Ar-40-C-12 and (ClO+)-Cl-37-O-16 ions at the chromium masses m/z 52 and 53 were reduced in intensity by approximately 2-3 orders of magnitude by using 1.0 ml min(-1) NH3 as reaction cell gas in the DRC while a q value of 0.6 was used. The limits of detection for Cr-52 and Cr-53 were 0.015 and 0.024 ng ml(-1) Cr, respectively. This method was applied to determine Cr in NRCC SLRS-3 Riverine Water reference sample, NIST SRM 1643d Trace Elements in Water, NIST SRM 2670 Urine reference sample and several water and urine samples collected locally. The external calibration method and isotope dilution method were used for the determination of Cr in selected samples. The results for the reference samples agreed satisfactorily with the reference values. Results for other samples analyzed by different quantitation methods agreed satisfactorily. Precision between sample replicates was better than 20% for most of the determinations.