Determination of Pu in urine at ultratrace level by sector field inductively coupled plasma mass spectrometry

A new analytical procedure has been developed for the determination of Pu in urine at the low ag ml(-1) concentration level by double-focusing sector field inductively coupled plasma mass spectrometry (ICP-SFMS). One liter of urine doped with 4 pg (242)Pu was analyzed after co-precipitation with Ca(3)(PO(4))(2) followed by extraction chromatography on TEVA resin in order to enrich the Pu and remove uranium and matrix elements. Figures of merit of ICP-SFMS for the determination of Pu were studied using two nebulizers, PFA-100 and direct injection high-efficiency nebulizer (DIHEN), for solution introduction with uptake rates of 0.58 and 0.06 ml min(-1), respectively. The sensitivity for Pu in ICP-SFMS was determined to be 2000 and 1380 MHz ppm(-1) for the PFA-100 and DIHEN nebulizers, respectively. Due to the low solution uptake rate of DIHEN the absolute sensitivity was about seven times better and yielded 1380 counts fg(-1) in comparison to 207 counts fg(-1) measured with the PFA-100 nebulizer. Recovery using (242)Pu tracer was about 70%. The limits of detection for (239)Pu in 1 l of urine, based on an enrichment factor of 100 for PFA-100 nebulizer and 1000 for DIHEN, were 9 x 10(-18) and 1.02 x 10(-18) g ml(-1), respectively. Measurements of (240)Pu/(239)Pu isotopic ratio in synthetically prepared urine standard solution yielded a precision of 1.8 and 1.9% and accuracy of 1.5 and 1.8% for the PFA-100 and DIHEN nebulizers, respectively. (C) 2004 Elsevier B.V. All rights reserved.