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Determination of Procaine and Tetracaine in Cocaine Samples by Variable-Angle Synchronous Fluorimetry

Volume 54, Number 11 (Nov. 2000) Page 1678-1683

Berzas Nevado, J.J.; Murillo Pulgarín, J.A.; Reillo Escudero, O.I.


Derivative variable-angle synchronous spectrometry has been developed to improve the selectivity of fluorescence measurements without loss of sensitivity. The first-derivative variable-angle synchronous scanning permits the rapid simultaneous determination of tetracaine and procaine in a mixture from 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 present in cocaine samples, but they can be eliminated by filtration, because they are insoluble in ethanol. Possible interference by other local anaesthetics likely to be present along with the compounds to be determined has been investigated. A complete and exhaustive statistical analysis of the experimental data was realized to demonstrate the validity of the method. The detection limit according to Long and Winefordner was 2.6 μg L-1 for procaine and 1.20 μg L-1 for tetracaine, and the detection limit proposed by Clayton was 3.00 μg L-1 for procaine and 1.38 μg L-1 for tetracaine.