Photometric determination of boron in potassium dihydrogenphosphate by the reaction of boron-containing macrobicyclic iron(II) nioximate formation

The possibility of photometric boron determination by the reaction of the formation of the macrobicyclic complex Fe(Nx)(3)(BOH)(2) in nioxime-boric acid-Fe(II) system is demonstrated. The optimal conditions for the reaction are found to be: pH 3.2+/-0.3 whereas the concentrations of nioxime, iron(II) and ascorbic acid should be greater than or equal to 8x10(-3), 7x10(-5) and greater than or equal to 5x10(-3) M, respectively. The absorbance is measured at 447 nm. Beer's law is valid within the range from 0.2 to 2.0 mu g/ml of B(III). The relative standard deviation of the determination of 5 mu g of B(III) is 0.16 (n=5). The technique is applicable for the determination of B(III) in quantities up to 5x10(-4)% in KH2PO4 crystals and in solutions for their growth. (C) 1999 Elsevier Science B.V. All rights reserved.