Flow injection spectrophotometric determination of boron with D-sorbitol using Methyl Orange as an indicator

Abstract

A spectrophotometric method for the determination of boron by flow injection, based on the complexation reaction between D-sorbitol and boric acid followed by the acid–base reaction of Methyl Orange, is described. Under the optimum conditions, the calibration graph was essentially linear up to 1.2 mg l^–1 of boron (120 µl injections) and the detection limit was 0.02 mg l^–1(signal to noise ratio = 3). Twenty samples can be analysed per hour with a relative standard deviation of 0.28–0.54%. The method was applied to the determination of boron in commercial eye lotions. By using a 0.6% m/v sodium chloride solution as the carrier stream, boron in sea-water samples was also determined.