ELECTROCHEMICAL QUANTIFICATION OF IBUPROFEN IN COATED TABLETS USING BUCKYPAPER-BASED MULTI-WALLED CARBON NANOTUBE-MODIFIED ELECTRODES

Abstract

Illicit and unregulated pharmaceutical trade poses a growing public-health risk, particularly for widely self-medicated non-steroidal anti-inflammatory drugs such as ibuprofen (IBU). Here, we report a portable electroanalytical approach for the quantification of IBU in marketed coated tablets using buckypaper (BP)-based multi-walled carbon nanotube (MWCNT) electrodes. A BP-MWCNT sheet was transferred by a simple stamping procedure onto two transducers: a glassy carbon electrode (GC/BP) for differential pulse voltammetry (DPV) and a screen-printed electrode (SPE/BP) coupled to batch injection analysis (BIA) for amperometric, high-throughput screening. IBU exhibited an irreversible anodic response on BP-modified electrodes, with a pH-dependent peak potential enabling estimation of an operational interfacial pKa (~5.0) from Ep–pH trends. Quantification was linear from 0.3 to 1.0 mM. GC/BP–DPV delivered LOD/LOQ of 0.041/0.123 mM, while SPE/BP–BIA improved sensitivity (LOD/LOQ 0.022/0.066 mM) under hydrodynamic conditions using 10 µL injections. Accuracy was verified in commercial tablets, yielding recoveries near 100% (e.g., 103.2% for GC/BP and 100.2% for SPE/BP by external calibration) with low coefficients of variation. Application to unregulated street-market samples distinguished compliant tablets (~99%) from a substandard batch (~79%), below pharmacopeial limits (90–110%). Overall, the proposed BP-MWCNT workflow is positioned as a practical point-of-sale tool for shelf-level post-market monitoring in regulated retail, while also enabling rapid screening of tablets obtained from informal outlets.