Fast, simple and reliable routine determination of 23 elements in urine by ICP-MS

Abstract

The paper presents a method for the fast, simple and reliable routine determination of As, Ba, Be, Co, Cd, Cu, Cr, In, Li, Mn, Mo, Ni, Pb, Pt, Rh, Sb, Se, Sn, Tl, U, V, W and Zn in urine by inductively coupled plasma mass spectrometry (ICP-MS) with an octopole based collision cell. The complete method validation for all elements is described, including the evaluation of short- and long-term stability, the analysis of different reference materials and the discussion of precision and accuracy in internal and external quality assurance. The urine samples were analysed directly after a 1/5 (v/v) dilution with 1% (v/v) nitric acid. The sample introduction system consisted of a robust Babington nebulizer for sample introduction into the ICP and a torch with an injector tube with an inner diameter of 2.5 mm. Combined with a low sample aspiration rate (0.4 ml min⁻¹) these applied ICP operating conditions enable the analysis of 500 samples without clogging of the nebulizer and deposition of particles in the injector tube. Limits of detection are in the range 0.4 ng l⁻¹ (for U) to 143 ng l⁻¹ (for Se) calculated to the undiluted urine. Spectral interferences from polyatomic ions were removed by adding 3.2 ml min⁻¹ helium (for As, Ba, Cd, Cr, Cu, Mo, Mn, Ni, Rh, V, Zn) or 3.4 ml min⁻¹ hydrogen (for Se) as collision gas. The analysis results of 63 real urine samples from non-exposed human subjects are presented. ICP-MS fitted with a collision cell enables the simultaneous determination of all 23 elements either in their essential concentration range or at concentration levels relevant for occupational and environmental health. For some elements (Rh, Pt, W, Mn) most of the concentrations in urine are below the limit of quantification, for other elements (Li, Pb, Co, Tl Cu, Zn, Se) good agreement with previous studies was found, while for a further group of elements (Be, Cr, Ni, Cd) new results or useful statistical data are presented.