Ultra-trace detection of methamphetamine in biological samples using FFT-square wave voltammetry and nano-sized...

An efficient voltammetric method for trace level monitoring of methamphetamine (MTM) stimulant drug in the human urine and serum samples is established. This method is based on fast fourier transform square wave voltammetric (FFT-SWV) determination of MTM at a molecularly imprinted polymer (MIP)/multi-walled carbon nanotube (MWCNTs)-modified carbon paste electrode. Voltammetric techniques development for electrochemical assay of MTM is a challenge, due to the weak electroactivity of this drug. Herein, MTM-imprinted nanopolymer was synthesized, using a simple precipitation polymerization method. The resulting polymer, along with MWCNT was then used to fabricate the modified carbon paste electrode which showed a well-defined anodic peak for MTM at about +1.0 V(vs. Ag/AgCl); whereas, the related blank electrode exhibited considerably lower signal at the same conditions. Utilizing the highly efficient MIP, MWCNTs (which increased the charge transfer phenomenon at the electrode surface) and the advanced electrochemical technique of FFT-SWV (which increased the created signal intensity) caused this method to be a high sensitive and selective approach for MTM measurement. In the optimum experimental conditions, the proposed sensor, exhibited linear response range of 1.0 × 10^-8 -1.0 × 10^-4 mol L^-1 and the detection limit of 8.3 × 10^-10 mol L^-1 with acceptable relative standard deviations (RSD%) for real samples (1.0-3.5%). Herein, the first MIP-based voltammetric sensor for MTM which also exhibits the lowest detection limit, ever reported, is introduced. This approach seems to provide an effective way for rapid screening of MTM in human urine and serum samples.