Synthesis of novel poly(methacrylic acid)/β-cyclodextrin dual grafted MWCNT-based nanocomposite and its use as electrochemical sensing platform for highly selective determination of cocaine

The assessment of a novel electrochemical sensing platform based on poly(methacrylic acid) (poly(MAA)) and beta cyclodextrin (beta-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/beta-CD at 3.0 mg mL(-1) concentration in DMF containing 0.7% of Nafion (R) was cast on the surface of glassy carbon electrode (GCE) by the drop-castingmethod. 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 beta-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 mu mol L-1 with a limit of detection (LOD) of 3.6 mu mol 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.

Automated summary

A novel electrochemical sensing platform based on multi-walled carbon nanotubes grafted with poly(methacrylic acid) and beta-cyclodextrin was developed for highly sensitive and selective cocaine determination in seized samples. The nanocomposite modified electrode showed improved selectivity and sensitivity in cocaine determination due to the synergistic effect of MWCNT, poly(MAA), and beta-CD. The proposed method demonstrated outstanding selectivity towards cocaine even in the presence of common adulterants in seized samples, providing accurate detection results confirmed by HPLC-DAD.