Anion-exchange chromatographic behaviour of the complex of boron with H-resorcinol: sensitive determination of boric acid

Abstract

The chromatographic behaviour of H-resorcinol and its anionic boron complex has been studied using high-performance liquid chromatography with an anion-exchange column. The anionic boron complex formed in an aqueous medium was injected on to the column (TSK gel IC-Anion PW, 5 cm × 4.6 mm i.d.) and detected at 510 nm. The boron complex and the excess of the reagent were separated completely on the column using perchlorate ion as eluent. The relationship between the capacity factor of the boron complex and the concentration of the eluent ion showed that the boron complex was a trivalent ion, and its capacity factor was almost unchanged at pH 4–10. From a kinetic study, the formation of the complex was found to be first-order with respect to the concentration of H-resorcinol in the presence of a large excess of the latter. The formation of the complex was accelerated, although the yield of the complex decreased, with an increase in temperature: 85 °C was adopted. The calibration graph was rectilinear up to 0.075 µg of boron per 5 ml of sample solution, the detection limit was 0.02 p.p.b and the relative standard deviation for 0.05 µg of boron was 0.58%.