The application of derivative spectrophotometry for the simultaneous determination of cocaine and other local anesthetics.

Part I. Cocaine-Lidocaine Mixtures A rapid procedure based on second-derivative UV spectrophotometry is proposed for the simultaneous determination of cocaine and lidocaine. The optimum magnitudes are chosen in terms of response linearity, sensitivity, relative percent error, relative recovery data, and reproducibility. Part II. Cocaine-Procaine Mixtures A derivative spectrophotometric method based on second-derivative ultraviolet absorption spectra has been developed for the simultaneous determination of cocaine and procaine. Several derivative magnitudes have been investigated. A statistical analysis of the results is reported. Part III. Cocaine-Tetracaine Mixtures A simple method has been developed for the simultaneous determination of cocaine and tetracaine by measuring the amplitudes of the positive peak at 286.6 nm and the negative peak at 313.9 nm with respect to zero baseline. Part IV. Cocaine-Benzocaine Mixtures Derivative ultraviolet spectrophotometry has been used for the simultaneous determination of cocaine and benzocaine. Both cocaine and benzocaine can be assayed by measurement of, respectively, the peak-to-peak amplitude D261.4,277.4 and the peak-to-zero amplitude D299.4. The method is applied to simulated street samples of cocaine.