1-(2-hydroxy-3-methoxybenzylideneamino)- 8-hydroxynaphthalene-3,6-disulfonic acid as a reagent for the spectrophotometric determination of boron in ceramic materials

Abstract

A sensitive and selective spectrophotometric method for the determination of boron is described. The method is based on the colour reaction between boron and the reagent 1-(2-hydroxy-3-methoxybenzylideneamino)- 8-hydroxynaphthalene-3,6-disulfonic acid (HMOA). In a HOAc–NH₄OAc buffer of pH 5.5, HMOA reacts with boron to form a 1∶2 yellow complex with a maximum absorption at 423 nm. The absorbance (λ_max = 423 nm) is linear up to 1.2 μg ml⁻¹ boron in aqueous solution with a repeatability (RSD) of 1.12%. The molar absorptivity and Sandell’s sensitivity are 7.19 × 10³ l mol⁻¹ cm⁻¹ and 0.0015 μg cm⁻², respectively. The limit of quantification and limit of detection were found to be 17.1 and 5.2 ng ml⁻¹, respectively. The interference of various ions was examined in detail. All the metal ions studied can be tolerated in considerable amounts; in particular, the tolerance limits of Fe, Al, Zn, Ca and Mg are superior to those of other reagents such as Azomethine-H and Azomethine-HR. The proposed method was applied to the determination of boron in ceramic materials with satisfactory results.