Determination of borates in caviare by ion-exclusion chromatography

A specific and rapid analytical procedure for the determination of borates in caviare was developed using ion-exclusion chromatography. Products require minimal pre-treatment, are simply extracted with eluent and filtered prior to chromatography. Isolation of the analyte as a 2:1 sorbitol-borate complex was accomplished using an anion exchange column with an eluent consisting of 2 mM heptafluorobutyric acid + 50 mM sorbitol with conductivity detection [corrected]. Among five sugar alcohols examined for complexation, sorbitol was found to provide optimum resolution and a 3-4 times enhancement of response over borate anion alone. The response of the complex was linear over at least a 100 fold range in concentration (0.1-10 micrograms boron/ml) with a correlation coefficient of 0.9997. Using a boric acid standard solution, the limits of detection and quantitation were 0.065 microgram/ml and 0.216 microgram/ml, respectively, calculated as boron. Replicate analyses (n = 5) for samples having commercially added borate (equivalent to 300-1000 micrograms/g boron) gave RSD values of 1.18-2.03%. Recoveries of borate from fortified samples having commercially added borate present varied from 94.5 to 101.1% while untreated samples exhibited recoveries of 78.5-108.0% over a concentration range of 23-1039 micrograms/g, calculated as boron.