Sequential Second Derivative Spectroscopy of Cocaine and Adulterants in Street Drug Samples. Part I: Cocaine, Procaine, and Lidocaine

Abstract A sequential spectrophotometric method for the resolution of mixtures of cocaine, procaine and lidocaine in powder samples is proposed. The analytes are determined sequentially in the following order: 1st-Procaine, 2nd-Cocaine and 3rd-Lidocaine. The three determinations are carried out in phosphate buffer at pH 7.8. This solvent was selected as alternative to 0.1M HCl and NaOH, because the spectral characteristics, solutions stability and reproductibility were suitable.