Determination of uranium by flow injection inductively coupled plasma mass spectrometry

A flow injection (FI) system for the on-line determination of uranium in environmental samples has been characterized and tested. The simple Fl manifold uses off-the-shelf components to precisely manipulate the carrier, sample, eluent, and washing streams through a column separation module. The separation module preconcentrates the sample by a factor of 30 and removes the potentially interfering environmental matrix. TRU(TM), a commercially available resin for extraction chromatography, is packed into a glass separation column (5 X 50 mm) in the limited dispersion (D = 2.8) FI system. Detection is performed by using inductively coupled plasma mass spectrometry (ICP-MS). Results are presented for the U-238 in groundwater samples. The total analysis time for each 5.0-ml aqueous sample is 6 min. The determination of detection limit for U-238 is 0.30 ng/l. By using certified groundwater samples, a precision of 1.1% (n = 4) and accuracy of +/-1.8% for U-238 at 62.6 ng/l were observed. We also report the design and preliminary testing of a second FI-ICP-MS system that minimizes the influence of polyatomic ions (e.g., (UH+)-U-238) On the determination of minor actinides (e.g., Pu-239(+)) by ICP-MS.