Ephedrine Determination in Human Urine Using a Carbon Paste Electrode Modified with C₁₈Bonded Silica Gel

Abstract

Abstract An electrochemical method by adsorptive stripping voltammetry with a modified carbon paste electrode with C18 bonded silica gel is described for the determination of ephedrine in human urine samples. The preconcentration step is performed at open circuit and constant stirring (1000 rpm) in 5×10−4 M sodium hydroxide and the measurement step in ammonia-ammonium chloride buffer (pH=10.0; 0.2 M) by linear scan voltammetry to 150 mVs−1 between 0.20 and 1.10 V. With the proposed method, ephedrine can be directly determined in urine, a relative standard deviation of 3.4% (n=12) and a detection limit of 270 μgmL−1 for a 2 minute preconcentration time, were obtained.