Simultaneous determination of amoxicillin and clavulanic acid using MPA-capped AgInS₂ quantum dots: A fluorescence-based chemometric approach

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Due to the widespread clinical use of their co-formulated form, the simultaneous and accurate determination of amoxicillin (AMX) and clavulanic acid (CLA) in pharmaceutical formulations is essential, calling for the development of simple, rapid, cost-effective, and reliable analytical methodologies. Therefore, an innovative and novel spectrofluorimetric method was developed for the simultaneous determination of both AMX and CLA in pharmaceutical formulations based on a multiplexed detection, using AgInS₂ quantum dots (QDs) capped with mercaptopropionic acid (MPA) as a PL probe, combined with chemometrics. Several QDs were synthesised and evaluated to achieve the highest sensitivity towards both analytes. Different interaction mechanisms were observed for each analyte. A full factorial experimental design was employed to ensure robust results and assess the main effects and their interactions of both analytes. The acquired kinetic fluorescence data were modelled using an unfolded partial least squares (U-PLS) model. The optimisation of the U-PLS models involved the study of different spectral regions. This methodology revealed that the entire spectral region yielded the best results, with accuracies of 2 % and 11 % for AMX and CLA, respectively, in terms of the relative error of prediction (REP). Moreover, this method was compared with the official USP chromatographic method, and no statistically significant differences were observed, thereby validating the precision and reliability of the developed method. This simple, rapid, and cost-effective analytical methodology can serve as a valuable alternative to the official chromatographic method, eliminating the need for toxic solvents. • Cd-free AgInS₂ QDs were used as PL probes for multiplexed detection of AMX and CLA. • Kinetic PL data were analysed using unfolded partial least squares (U-PLS). • Combined probe data enhanced prediction accuracy and model robustness. • Achieved REPs of 2 % (AMX) and 11 % (CLA) with strong correlation to the USP method. • Simple, fast, and eco-friendly alternative to conventional chromatographic methods.