RAPID FLUORIMETRIC DETERMINATION OF PHENOTHIAZINES EMPLOYING INSITU PHOTOCHEMICAL OXIDATION

Phenothiazine derivatives are among the most widely used drugs for treatment of psychiatric patients. Exposure of 5 phenothiazine drugs (perphenazine, chlorpromazine, fluphenazine, trifluoperazine and thioridazine) to an intense UV source results in simultaneous photooxidation of the drugs and fluorescence excitation of the products. This photochemical-fluorimetric method is unique because no addition of diluting reagents is needed; lowered detection limits result in convenient determinations between 10 and 1000 ppb of perphenazine, chlorpromazine, fluphenazine and trifluoperazine. Correlation coefficient [r] for linear regression of either digitally integrated intensities or analog fluorescence peak intensities vs. initial drug concentrations are all greater than 0.9990. Thioridazine yields nonlinear calibration curves, but a satisfactory (r of 0.9996) linear approximation can be used between 10 and 200 ppb. Optimum values of pH, emission wavelength and photolysis time are reported for each drug.