Kinetic quantification of sodium salicylate in human serum and wine

A rapid, relatively sensitive and simple kinetic-spectrophotometric method for determining sodium salicylate content has been developed and validated. This method was based on the Fenton reaction that involved mixing of ferrous ions, hydrogen peroxide and sodium salicylate in acetic buffer medium. Ferrous ions, oxidized by hydrogen peroxide, formed with salicylate anion purple complex whose degradation started immediately. This effect was monitored by the decrease of absorbance at 525 nm. The experimental results showed that the most favorable conditions for complex degradation are: pH = 3.9, = 4.7 × 10 −5 M, and = 1/150. The activation energy ( E a ) calculated from the slope ( = 2.84 × 10 3 ) was 54.3 ± 0.6 kJ/mol. The absorbance increased linearly with the increment of sodium salicylate concentration ( r = 0.9983). The system obeyed Beer’s law in a range of 0.93–9.3 μg/mL of sodium salicylate concentration. The calculated values for the detection limit, according to two formulas, available in the literature, were found to be 0.67 and 0.48 μg/mL. The variables affecting the rate of the proposed reaction were investigated. The relative standard deviations for five-replicate determinations of 0.93, 3.31, and 9.30 μg/mL of sodium salicylate were calculated to be 6.80, 2.95, and 1.71%, respectively. The proposed method has been successfully applied to determining sodium salicylate in human serum and wine and validated by HPLC (high-pressure liquid chromatography) reference method.