Determination of actinide elements at femtogram per gram levels in environmental samples by on-line solid phase extraction and sector-field-inductively coupled plasma-mass spectrometry

An on-line solid phase extraction method has been developed for the determi nation of Th-232, Np-237, U-238, Pu-239 Pu-240, Am-241 and Am-243 in biolog ical certified reference material using a column containing TRU-Spec (TM) r esin coupled with sector-field inductively coupled plasma-mass spectrometry . Absolutes detection limits were 0.7, 0.85, 0.6, and 0.65 fg for Np-237, P u-239, Am-241 and Am-243, respectively. The Pu-239 was determined in NIST H uman Liver (963 +/- 297 fg g(-1) compared with a certified value of 848 +/- 161 fg g(-1)) using a dry and wet ashing sample preparation method, and in a spiked cabbage reference material (394 +/- 54 fg g(-1) compared to an in dicative value of 467 fg g(-1)) using microwave digestion. Sequential separ ation of Pu and U was achieved by on-column reduction of mt with titanium(I II) chloride and elution in 4 M HCl to facilitate the determination of Pu-2 39 in samples containing high levels of U-238, thereby eliminating the inte rference of (UH+)-U-238-H-1 at m/z 239. The sequential elution procedure wa s used to determine Pu-239 in NIST human lung (814 +/- 55 fg g(-1) compared with a certified range of 227-951 fg g(-1)) and NIST Rocky Flats Soil (242 3 +/- 137 fg g(-1) compared with a certified value of 3307 +/- 248 fg g(-1) ). (C) 2001 Elsevier Science B.V. All rights reserved.