SIMULTANEOUS MULTIVARIATE SPECTROPHOTOMETRIC ANALYSIS OF EAR DROPS CONTAINING A TERNARY MIXTURE OF ANTIPYRINE, SULFATHIAZOLE, AND RIVANOL

The use of multivariate calibration is reported for the analysis of ear drops, which contain the anti-inflammatory antipyrine, the antibiotic sulfathiazole and the analgesic rivanol. The components are present in a 10 : 10 : 1 ratio, and are all dissolved in glycerin. The resolution of this mixture has been accomplished without prior separation or derivatization, with the aid of partial least-squares (PLS-1) regression analysis of electronic absorption spectral data. A sensor selection method based on the minimization of the cross-validation square error for each component was performed in order to optimize the method. The analytes have been simultaneously determined with accuracy and precision, even for the minor component rivanol which is present in a 1 : 10 ratio with respect to both sulfathiazole and antypirine. Estimated limits of detection are: antypirine, 0.3 mg L-1, sulfathiazole, 0.1 mg L-1 and rivanol, 0.1 mg L-1.