F. Macleod et al., STABLE-ISOTOPE DILUTION - MASS-SPECTROMETRY FOR DETERMINING TOTAL SELENIUM LEVELS IN PLANTS, SOILS AND SEWAGE SLUDGES, Talanta, 43(7), 1996, pp. 1091-1098
Quantitation of selenium in plants, soils and sludges was achieved by
isotope dilution-mass spectrometry using a benchtop instrument. Sample
s for analysis were spiked with Se-76 isotope solution. Plant material
was digested on a heating block at 150 degrees C using a mixture of n
itric acid and hydrogen peroxide. Selenium in soils and sludges was re
leased by treatment with nitric acid followed by digestion with nitric
and hydrofluoric acids. Selenium in the digests was reduced to Se(IV)
with hydrochloric acid and derivatised with nitro-1, 2-phenylenediami
ne to 5'-nitropiazselenol. Analysis by gas chromatography-mass spectro
metry using selected ion monitoring was validated using certified refe
rence materials (CRMs) and gave results within the certified range wit
h a low standard deviation. The CRMs plant (Chinese cabbage leaves) an
d soil (Chinese soil) were found to contain (+/-95% confidence limits)
0.091(+/-0.007) mu g g(-1) and 1.67(+/-0.04) mu g g(-1)Se respectivel
y. The certified values were 0.083(+/-0.008) mu g g(-1) and 1.56(+/-0.
12) mu g g(-1) respectively. The selenium content of four different fr
eely drained acid Scottish soils under grasslands was in the range 0.5
-0.8 mu g g(-1) air-dried soil. Sewage sludges were found to contain m
easurably more selenium than the soils, and samples of three sludges t
aken from sites in the UK contained between 1.1 and 3.5 mu g g(-1) dry
matter.