Anions in non saline waters - Determination of Anions in Natural and Treated Waters - page 105

less satisfactory at higher concentrations. This may be the result of greater carbon-boron
interactions at higher concentrations; this suggestion is supported by the broader peaks
obtained. Dilution of samples may therefore be necessary, to ensure that they are run in
the optimum range, when higher concentrations of boron are expected.
2.9.5 Ion selective electrodes
These are available commercially for the determination of borate in water.
2.9.6 Ion chromatogrophy
Erkelens et al. [38] attributed three extraneous peaks (system peaks) produced from
single-column ion chromatography of inorganic anions to complex formation of borate
esters or polyhydroxy compounds (formed in the eluant at high pH) with polyvalent
cations such as calcium. The behaviour of three system peaks obtained using high pH
borategluconate buffer and a conductivity detector was studied in detail. All negative
system peaks were avoided by treating samples with a cation exchanger in the sodium
form prior to injection.
Hill and Lash [113] have also discussed the determination of borate in non saline
water.
The application of this technique is also discussed under multianion analysis in section
12.2.5.
2.9.7 High performance liquid chromatography
Zun et al. [114] achieved a good separation of the anionic complex formed between boric
acid and chromotropic acid using an ion exchange complex (TSKgelic-Anion-PW). This
method showed few interferences from foreign ions, molybdenum(VI) and vanadium(V)
causing positive errors at levels above 10µM.
2.9.8 Preconcentration
The application of preconcentration techniques is discussed in section 15.1.2.
2.10 Borofluoride
2.10.1 Ion chromatography
The application of this technique is discussed under multianion analysis in section 12.2.5.
2.10.2 High performance liquid chromatography
The application of this technique is discussed under multianion analysis in section
13.1.1.5.