A. Al-ammar et al., Improving boron isotope ratio measurement precision with quadrupole inductively coupled plasma-mass spectrometry, SPECT ACT B, 55(12), 2000, pp. 1861-1867
A method was developed to improve the precision of inductively coupled plas
ma quadrupole mass spectrometry (ICP-QMS) for the determination of boron is
otope ratios (B-11/B-10) in various environmental materials including seawa
ter. This approach is based on the common analyte internal standardization
(CAIS) chemometric algorithm. The sample solution obtained after digestion
is spiked with lithium, and both Li-7/Li-6 and B-11/B-10 values are measure
d using long-counting periods (20 min). The CAIS algorithm corrects the mea
sured B-11/B-10 values for (a) statistical fluctuations resulting from shor
t-term noise; (b) drift in B-11-to-B-10 ratio as a result of long-term devi
ation in instrumental parameters likely to occur during long counting times
; (c) change in B-11-to-B-10 ratio caused by variation in matrix elements c
oncentrations; and (d) drift in mass bias correction factor. Comparing boro
n isotopic ratios in seawater measured by conventional and the new isotope
ratio methods validates the procedure. A synthetic isotopic mixture of boro
n SRM 951 and enriched B-10 SRM 952 also was examined. The CAIS method prov
ided a measured boron isotopic ratio precision of 0.05% R.S.D. while elimin
ating 5.1% matrix concentration error and 0.25% instrumental drift error. (
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