On-line UV-photooxidation with peroxodisulfate for automated flow injection and for high-performance liquid chromatography coupled to hydride generation atomic absorption spectrometry
Dl. Tsalev et al., On-line UV-photooxidation with peroxodisulfate for automated flow injection and for high-performance liquid chromatography coupled to hydride generation atomic absorption spectrometry, SPECT ACT B, 55(4), 2000, pp. 339-353
An automated on-line UV photooxidation with peroxodisulfate of some environ
mentally relevant organoarsenic and organotin compounds in a system built f
rom commercially available modules has been studied and optimised with a vi
ew to both species-independent quantification of the total arsenic or tin i
n samples containing different organic species by flow injection hydride ge
neration atomic absorption spectrometry (FI-HGAAS) and speciation analysis
by coupled high-performance liquid chromatography (HPLC) with HGAAS detecti
on. For organoarsenicals, the reaction with alkaline peroxodisulfate in a 1
0-15-m knotted reactor for > 1.5 min insures > 90% transformation of inorga
nic As(III) and six organoarsenic species to arsenate: monomethylarsonate,
dimethylarsinate, arsenobetaine, arsenocholine, trimethylarsine oxide and t
etramethylarsonium. For organotins, the UV photooxidation with acidic perox
odisulfate at 95-100 degrees C provides recoveries of > 80% for the inorgan
ic tin, dimethyltin, trimethyltin, triethyltin, tripropyltin, triphenyltin,
monobutyltin, dibutyltin and tributyltin but only approximately 15% for te
trabutyltin. The best characteristic masses in integrated absorbance (A(int
)) and peak-height (A(p)) measurements, respectively, are 30 pg and 480 pg
for arsenic(V) and 22 pg and 410 pg for tin(IV), employing 100-mu l injecti
ons. The RSDs are 5.5% and 8.5% at 5 ng As(V) levels and 4.3% and 6.4% at 1
0 ng Sn(IV) levels in A(int) and A(p) modes, respectively. The limits of de
tection (LOD, 3 sigma) for As are 7 mu g l(-1) and 4 mu g l(-1) in FI-UV-HG
AAS and HPLC-UV-HGAAS, respectively. The LODs for i-Sn(IV) are 2 mu g l(-1)
in FI-UV-HGAAS, with both A(int) and A(p) measurements. The sample through
put rates are 20 and 12 samples per hour with 10-m and 15-m knotted reactor
s (i.d. 0.5 mm), respectively. Urine certified reference materials containi
ng 0.052-0.48 mu g ml(-1) As have been analysed for their total arsenic con
tent. (C) 2000 Elsevier Science B.V. All rights reserved.