Determinação de escopolamina em bebidas e urina empregando voltametria de onda quadrada e eletroforese capilar

Abstract

Scopolamine (SCP) is an alkaloid used to prevent motion sickness and as an adjunct to anesthesia application. However, due to the effects on the central nervous system, this drug is also added to beverages, with criminal intent, a practice commonly known as "Good evening, Cinderella" In this thesis two simple and rapid electrochemical methods for the determination of SCP in beverage and urine samples were developed as a screening process for adulteration known as "Good Night, Cinderella". One method was based on batch injection analysis with square wave voltammetric detection (BIA-SWV) and the other on capillary electrophoresis with contactless conductometric detection (CE-C4D). In BIA-SWV, the samples were analyzed after dilution in supporting electrolyte (H2SO4 0.5 mol L-1) and a boron doped diamond electrode (BDD) was used to promote the electrooxidation of SCP resulting in an oxidation peak at +1.8 V (vs. Ag/AgCl(sat)). In addition to rapid screening of SCP, the quantification of SCP was also possible with recovery values between 87 and 113% and detection limit of 0.18 μmol L-1. The developed (CE-C4D) method allows rapid detection (tm <30 s) of SCP in beverages using 20 mmol L-1 histidine (+ NaOH until pH = 9.5) as the background electrolyte. SCP screening and quantification was possible after simple dilution of beverage samples in water, with recovery values between 93 and 103% and detection limit of 7.8 μmol L-1. In addition, the CE-C4D system was also successfully used in the detection and quantification of SCP in urine using histidine/DMX/NaOH (20 mmol L-1/10 mmol L-1/12 mmol L-1; pH = 8,0) as the background electrolyte. Quantification of SCP in urine was possible using sample dilutions between 10 and 30% (v/v), with recovery values between 85 and 112% and detection limit of 2.3 μmol L-1.