SIMULTANEOUS SPECTROPHOTOMETRIC DETERMINATION OF PHENOLIC ANTIOXIDANT (BHA AND BHT) CONCENTRATIONS IN PHARMACEUTICAL PREPARATIONS AND CHEWING GUMS USING THE H-POINT STANDARD ADDITION METHOD

A simple, rapid, and sensitive spectrophotometric method was developed for the simultaneous determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) concentration in pharmaceutical preparations and chewing gums, without prior separation steps, using the H-point standard addition method (HPSAM). The concentration of one antioxidant was calculated by overlapping spectra at two appropriately selected wavelengths at which the interferent, other antioxidant, should has the same absorbance value. Absorbances at two pairs of wavelengths, 265 and 288 nm (with BHA as analyte) or 288 and 293 nm (with BHT as analyte) were monitored, while adding standard solutions of BHA or BHT, respectively. Calibration graphs were determined at 4-20 mu gml(-1) (r = 0.9981) for BHA and 20-100 mu gml(-1) (r = 0.9940) for BHT in binary mixtures. The proposed method was tested and validated using various parameters according to ICH guidelines. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.48 and 1.51 mu gml(-1) for BHA and 0.72 and 2.41 mu gml(-1) for BHT, respectively. The percentage recovery ranges were 100.44-102.50 % for BHA and 96.45-100.04 % for BHT, with relative standard deviations (RSD) less than 1.48 % indicating reasonable repeatability of the method. The intra-day and inter-day precision tests showed reliable RSD values (< 2 %). The results obtained using HPSAM were statistically compared with results obtained using the derivative spectrophotometric method that was previously reported by us, showing high similarity between results.