Electrochemical behavior of methamphetamine and its voltammetric determination in biological samples using self-assembled boron-doped diamond electrode

An electrochemical behavior of methamphetamine on a self-assembled boron-doped diamond electrode was studied by cyclic voltammetry. Methamphetamine yielded a single irreversible oxidation peak at a higher positive potential of +1.23 V (vs. Ag/AgCl/3 M KCl electrode) in Britton-Robinson buffer solution at pH 10. The nature of the electrode reaction was found to be diffusion controlled with minor contribution of adsorption. The differential pulse voltammetric methodology was proposed for the sensitive determination of methamphetamine in a linear concentration range from 0.07 to 80 μM with a detection limit of 0.05 μM (7.46 μg L−1) and a good repeatability (relative standard deviation of 2.8% at 20 μM concentration level, n = 6). The effect of interfering agents (common urinary compounds) was appeared to be negligible confirming a favorable selectivity of method. The practical usefulness of method was demonstrated in the assessment of methamphetamine content in model human urine samples with good accuracy (recoveries varied from 93.4% to 97.6%). The proposed procedure could represent a suitable alternative to other analytical methods for the determination of low concentration levels of methamphetamine in biological samples. It may enable methamphetamine excreted in urine of drug addicted people to be assayed sensitively and selectively.