Determination of procaine and tetracaine in cocaine samples by variable-angle synchronous fluorimetry

Derivative variable-angle synchronous spectrometry has been developed to im prove the selectivity of fluorescence measurements without loss of sensitiv ity. The first-derivative variable-angle synchronous scanning permits the r apid simultaneous determination of tetracaine and procaine in a mixture fro m a single spectrum. The analysis was performed in 90% ethanol medium and 8 .10(-3) M NaOH. These local anaesthetics can be determined in the presence of large amounts of cocaine. Talc (hydrous magnesium silicate) and kaolin ( aluminum silicate hydroxide) are the most common compounds that can be pres ent in cocaine samples, but they can be eliminated by filtration, because t hey are insoluble in ethanol. Possible interference by other local anaesthe tics likely to be present along with the compounds to be determined has bee n investigated. A complete and exhaustive statistical analysis of the exper imental data was realized to demonstrate the validity of the method. The de tection limit according to Long and Winefordner was 2.6 mug L-1 for procain e and 1.20 mug L-1 for tetracaine, and the detection limit proposed by Clay ton was 3.00 mug L-1 for procaine and 1.38 mug L-1 for tetracaine.