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

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 ⩾8×10−3, 7×10−5 and ⩾5×10−3 M, respectively. The absorbance is measured at 447 nm. Beerʹs law is valid within the range from 0.2 to 2.0 μg/ml of B(III). The relative standard deviation of the determination of 5 μg of B(III) is 0.16 (n=5). The technique is applicable for the determination of B(III) in quantities up to 5×10−4% in KH2PO4 crystals and in solutions for their growth.