Improvement of on-line concentration/HPLC analysis method of boric acid using an anion-exchange column loaded with chromotropic acid and its application to trace determination of boric acid in natural waters from Iriomote Island, the Ryukyus

Abstract

A method for the on-line absorptiometric determination of trace amounts of boron in natural water samples was improved using a commercially available 1-cm anion-exchange column presorbed with chromotropic acid. On-line reaction and separation were achieved by controlling the pH in order to accelerate complex formation in the column by 3, and to stabilize the complex at pH 8 for selective elution of the 1: 2 complex and its detection at 350 nm. The analytical time for a 3.2 cm3 water sample was 12 min, and the detection limit was 0.06 μg dm-3. The method was applied to the boron analysis of natural water samples on Iriomote Is., the Ryukyus. The boric acid concentrations of rain and two river water samples were ranged from 3.1 to 40.8, 20.3 to 28.5 and 14.7 to 20.9 μg dm-3, respectively. In each case, the fraction of non-sea salt origin was estimated to be high, probably suggesting that the nss-B had been transported a long distance from the Asian Continent. © 2011 The Japan Society for Analytical Chemistry.