Comparison of two digestion methods for elemental determinations in plant material by ICP techniques

Two digestion procedures have been tested on plant samples for application in the determination of a wide range of major, minor, and trace elements by a combination of inductively coupled plasma atomic emission spectrometry ( ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The fir st is an open-vessel digestion with concentrated nitric acid and the second is a microwave digestion with a mixture of concentrated nitric acid and hy drogen peroxide. The detection limits were found to be controlled by instru mental capabilities in ICP-AES and by digestion blank levels in ICP-MS. The accuracy of the overall analytical procedures was estimated by analysis of a certified reference material. Among elements for which certified concent rations are available, good agreement between measured and reference values was found for 15 and 16 elements in the first and second procedure, respec tively. The precision was assessed from replicate analysis (including sampl e preparation) of reference material and a number of environmental samples and was found to be 5% RSD or better when analyte concentration exceeds qua ntification limit. Owing to the multielemental capabilities and to the wide analytical range of the ICP techniques used, more than 30 elements can be determined in plant materials at concentrations varying from tens of pg g(- 1) to wt%. (C) 1999 Elsevier Science B.V. All rights reserved.