Spectrometric determination of total antioxidant activity in chlorpromazine radical cation - ascorbic acid system.

UNLABELLED Through univalent oxidation chlorpromazine forms a colored and relatively stable radical cation with maximum absorbance at 525 nm, considered a redox mediator in a number of b iochemical reactions. AIM To develop a spectrometric method for the determination of total antioxidant activity based on the reaction of chlorpromazine radical capture by ascorbic acid (standard antioxidant). MATERIAL AND METHODS The calibration curve was drawn by monitoring the decrease in the absorbance of the preformed radical solution (obtained by oxidation of chlorpromazine by potassium persulfate in an acidic environment) depending on ascorbic acid concentration. RESULTS The method was validated. In the ascorbic acid concentration range 10-100 microM/L linearity was good (r2 = 0.9991). Limit of detection (LOD) was 3.13 microM/L and limit of quantification (LOQ) was 9.49 microM/L. System precision (RSD = 0.75%), method precision (RSD = 4.50%) and intermediate precision (RSD = 4.63%) were determined. The average recovery of 101.7% for the concentration range 91.1 -105.9% confirmed the accuracy of the method. CONCLUSIONS The method has a good linearity, precision, accuracy, and is easy to use for evaluation of antioxidant action of different products. Total antioxidant activity is expressed as ascorbic acid molar equivalents (AAE). The method has the advantage of using a radical involved in redox processes in the body.