Determination of boron by spectrophotometric FIA using Azomethine H

A spectrophotometric determination of boron with Azomethine H {1-(salicylidenamino)-8-hydroxynaphthalene-3, 6-disulfonic acid} by FIA has been conducted. A dualchannel FIA apparatus was used for the sake of both simplicity and convenience. A sample solution containing less than 1 ppm of boron was injected into a carrier stream (deionized water) and was merged with a reagent stream containing 0.25% (w/v) Azomethine H, 1% ascorbic acid, 1% EDTA and 0.8 M diammonium hydrogenphosphate buffer (pH 7.2). The mixture was flowed through 10 m long reaction tube (PTFE, 0.5 mm i.d.) at a flow rate of 0.9 ml/min. The absorbance was recorded at 425 nm. The calibration curve was linear over the range of 0.1 to 1.0 ppm of boron. The relative standard deviations (n=15) for 0.2 and 0.8 ppm of boron were 0.63 and 0.20%, respectively. The sample throughput was about 20 h-1. The proposed method was applied to the determination of boron in eye lotions.