The determination of boron in food and seed by spectrophotometry using a new reagent 3,4-dihydroxyazomethine-H

A new sensitive and selective reagent, 3,4-dihydroxyazomethine-H, was studied for spectrophotometric determination of boron in food and seed. Boron (III) reacts with 3,4-dihydroxyazomethine-H to form a 1:2 yellow complex in an ammonium acetate solution of pH 8.0, which has a maximum absorption peak at 430 nm. Under the optimal conditions, Beer's law was obeyed over the range 0 similar to 20 mu g of boron (III) in 25 ml of solution. The apparent molar absorptivity is 2.95 x 10(4) 1 mol(-1) cm(-1), in which the sensitivity is higher than 4.2-fold that of azomethine-H. The limit of quantification, limit of detection and relative standard deviations were found to be 5.1, 1.5 ng g(-1) and 1.08%, respectively. The influences of foreign ions on the determination of boron were also investigated in detail, most of the ions studied can be tolerated in considerable amounts. The reaction can be completed within 90 min and the absorbance of the complex remains maximum and almost constant for 24 h under room temperature from 0 to 35 degrees C, which is advantagous over other derivatives of azomethine-H reported remarkably. The proposed method has been successfully applied to the determination of boron in food and seed. (c) 2005 Elsevier Ltd. All rights reserved.