Fast and portable voltammetric method for the determination of the amphetamine adulterant ephedrine in natural over-the-counter weight-loss products

Abstract

This work focused on the development of a simple, fast, portable, and direct method for the determination of an amphetamine drug often used in adulteration of weight-loss products: ephedrine. The detection was conducted using the portable batch injection analysis system with square-wave voltammetric detection (BIA-SWV) and a bare BDD electrode as the working electrode. A linear range of 5.0 to 40 mg L−1 (3.0 × 10−5 to 2.4 × 10−4 mol L−1) with a detection limit of 0.13 mg L−1 (7.9 × 10−7 mol L−1) was achieved for ephedrine using 0.1 mol L−1 acetate buffer (pH 4.7) as the supporting electrolyte. Rapid screening protocols were developed as promising and interesting tools with potential applications in criminal forensic analysis applied to over-the-counter natural products and, additionally for anti-doping control in urine samples. Furthermore, the possibility of quantification of ephedrine in representative samples of products used to weight-loss purposes without any sample pretreatments was also shown.