Optimized solid phase extraction methodology for separation, and spectrophotometric determination of boron using amberlite XAD-16 resin modified with 2-(2-benzothiazolylazo)-4-methoxyphenol

Abstract

A highly selective and sensitive spectrophotometric method has been developed to determine trace amounts of boron in various biological and water samples. The method is based on adsorption of B(III) after complexation with 2-(2-benzothiazolylazo)-4-methoxy-phenol (BTAMP) in HOAc–NH₄OAc buffer at pH 5.5 on an amberlite XAD-16 resin in the presence of Triton X-114. The retained analyte on the resin can be recovered with 4.0 mL of 2.0 M sulfuric acid and boron is determined spectrophotometrically at λ_max 622 nm. Beer’s law is obeyed in the concentration range of 0.05–125 ng mL⁻¹ of B(III) in the measured solution. For more accurate results, the Ringbom optimum concentration range was found to be 0.2–110 ng mL⁻¹. The linear regression equation obtained was A = 0.413C (μg mL⁻¹) + 0.003 (r = 0.9994). The molar absorptivity was calculated to be 4.46 × 10⁵ L mol⁻¹ cm⁻¹ at 622 nm, whereas the Sandell sensitivity was found to be 2.42 ng cm⁻². Various parameters such as the effect of pH, reagent concentration, surfactant, and flow rate were studied. The interference of a number of metal ions on the determination of boron has been studied in detail. The proposed method was successfully applied to determine boron concentrations in biological materials, water and ceramic samples. In addition, excellent agreement was observed between the proposed and the reference methods.