LAUSR

Abstract The assessment of a novel electrochemical sensing platform based on poly(methacrylic acid) (poly(MAA)) and β-cyclodextrin (β-CD) grafted onto multi-walled carbon nanotubes (MWCNT) for highly sensitive and selective cocaine (COC) determination in seized samples is reported. Nanocomposite characterization was performed by FT-IR, Raman Spectroscopy, X-ray diffraction, TGA, SEM, TEM, nitrogen adsorption/desorption and static contact angle. The poly(MAA)/MWCNT/β-CD at 3.0 mg mL−1 concentration in DMF containing 0.7% of Nafion® was cast on the surface of glassy carbon electrode (GCE) by the drop-casting method. The nanocomposite modified electrode showed substantial improvement in terms of selectivity and sensitivity in the COC determination as a result of the synergic effect of MWCNT, poly(MAA), and β-CD. By using differential pulse voltammetry (DPV) under optimized conditions (scan rate of 28.0 mV s−1, pulse amplitude of 164.0 mV and modulation time of 7.0 ms) and at pH 7.0 in 0.1 mol L−1 Britton-Robinson (BR) buffer, a linear response range from 12.2 to 200.0 μmol L−1 with a limit of detection (LOD) of 3.6 μmol L−1 was obtained. The modified electrode showed outstanding selectivity towards COC determination even in the presence of adulterants usually found in seized COC sample, including caffeine, lidocaine, phenacetin, benzocaine, paracetamol, procaine, and levamisole. The proposed method was applied to COC determination in street seized sample and the accuracy was attested by HPLD-DAD.