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 2mm sorbitol, and conductivity detection was used. 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 mu g boron/ml) with a correlation coefficient of 0.9997. Using a boric acid standard solution, the limits of detection and quantitation were 0.065 mu g/ml and 0.216 mu g/ml, respectively, calculated as boron. Replicate analyses (n = 5) for samples having commercially added borate (equivalent to 300-1000 mu g/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 mu g/g, calculated as boron.