Spectrophotometric determination of boron based on charge transfer reaction.

Boron determination by a charge transfer spectrophotometric method is described. Accompanied the reaction, a charge transfer complex can be formed by lysine with sodium 1, 2-naphthoquinone-4-sulfonate and boron in alkaline solution (pH 12.00). Subsequently, a new reaction mechanism has been proposed and discussed. The absorbance at the maximal absorption wavelength is 574 nm and boron concentration agrees well with Beer's law in a range of 2.16-43.24 μg mL(-1). The linear regression equation is A=-0.01867+0.01326C (μg mL(-1)), with a linearly correlation coefficient of 0.9935. The relative standard deviation (R.S.D.) of eleven parallel determinations is 2.1% with a detection limit (3σ/k) of 2.00 μg mL(-1). The recovery ranges from 96.4% to 104.5% with the satisfactory results. This method has been successfully applied to determine boron in pharmaceutical samples directly.