Sensitive and Accurate Determination of Clopidogrel in Pharmaceutical Preparations Using Spectrophotometric, Microfluidic and Paper-Based Colorimetric Sensor Techniques

Clopidogrel, a widely used antiplatelet agent, requires reliable, cost-effective analytical methods for quality control.This study presents the development and validation of three new methods: spectrophotometric, microfluidic-based laser detection, and paper-based microfluidic devices (µPADs) for the analysis of clopidogrel in pharmaceutical formulations.All methods are based on the formation of a colored ion-pair complex between clopidogrel and acid alizarin black, exhibiting maximum absorbance at 512 nm.The reaction conditions, including reagent concentration, temperature, and time, were optimized, and a 1:1 drug-to-reagent stoichiometry was confirmed.The microfluidic system, fabricated from poly (methyl methacrylate) (PMMA) using laser engraving, offered high accuracy and low sample consumption.Meanwhile, the µPADs provided a portable, instrumentation-free alternative, utilizing digital image analysis (ImageJ) to quantify color intensity.Methods validation showed linearity ranges of 1-12 ppm (microfluidic), 2-16 ppm (µPADs), and 2-20 ppm (UV-Vis), with detection limits of 0.5, 1, and 1.25 ppm, respectively.Recovery rates ranged from 98.89% to 99.64%, and R² values exceeded 0.994 for all methods.These results demonstrate that the proposed techniques are rapid, accurate, and suitable for routine analysis of clopidogrel in resource-limited and laboratory contexts.