Ion chromatography determination of trace level bromate by large volume injection with conductivity and spectrophotometric detection after post column derivatisation
S. Valsecchi et al., Ion chromatography determination of trace level bromate by large volume injection with conductivity and spectrophotometric detection after post column derivatisation, J CHROMAT A, 864(2), 1999, pp. 263-270
Bromate is a well known by-product produced by the ozonisation of drinking
water; the allowed concentration for human consumption has to be regulated
to the low mu g l(-1) range. A direct injection, ion chromatographic method
was developed using a tetraborate eluent with serially connected conductiv
ity and spectrophotometric detection. Bromate was detected after post-colum
n reaction with fuchsin at 520 nm. Sample capacity was investigated by inje
cting large volumes (up to 6 ml) using a high total hardness and chloride t
ap water. Linear correlation of bromate response with volumes from 1 ml to
6 ml was demonstrated, the main limitation being the overlapping of the chl
oride peak with bromate. Up to 1.5 ml sample can be injected without any pr
e-treatment. With more than 1.5 mi injection volume, a sample pre-treatment
with a cartridge in Ag and H form, followed by a 10 min degassing in an ul
trasonic bath, was needed. This method was validated by analysing secondary
reference materials and real samples from a drinking water treatment plant
. The method was linear from the limit of quantification to 20 mu g l(-1).
Reproducibilities in tap water were 18% (5 mu g l(-1) n = 12) and 21% (1 mu
g l(-1), n=4) respectively for 1.5 and 6 ml injection volumes with conduct
ivity detection, and 17% at 0.5 mu g l(-1) (n=9) with spectrophotometric de
tection. Calculated detection limits were 0.5 mu g l(-1) (6 ml) and 2 mu g
l(-1) (1.5 ml) for conductivity detection and 0.3 mu g l(-1) (1.5 ml) for s
pectrophotometric detection. (C) 1999 Elsevier Science B.V. All rights rese
rved.