Rapid Point-of-Care Assessment of Paracetamol Intoxication via an Integrated Electrochemical-Colorimetric Method

This work addresses the detection and quantification of paracetamol (PAR) in human serum using a point-of-care approach, an essential assessment for intoxication cases in clinical analysis. Electrochemical and colorimetric methods have been widely reported for simple and fast determination of PAR in biological samples. However, most of these previous portable methods have neglected some aspects for a real-world clinical application of PAR intoxication, such as its toxic concentration range and a proper interference study in biological matrices. To fill this gap, we introduce a novel integrated sensing approach, combining colorimetric and electrochemical techniques for determining PAR. In contrast to other sensors, this work employs a simple screen-printed graphite electrode (SPE-Gr) combined with a colorimetric reagent (CR) for the rapid and selective detection of PAR in human serum. Analysis occurs via dual confirmation: after reaction between PAR and CR, first a color change can indicate intoxication levels, and the generated product is subsequently accurately quantified by square-wave adsorptive stripping voltammetry using a SPE-Gr. A wide linear range (4.5 to 1000 mg L^-1) for determining PAR was obtained, with a limit of detection (1.2 mg L^-1), covering its therapeutic and toxic concentrations for assessment of intoxication cases. High reproducibility was demonstrated by low relative standard deviations (RSDs < 2.0%) and consistent responses obtained with different disposable SPEs-Gr (n = 3). Analysis in real human serum with a comprehensive interference study showed a high selectivity and reliability of the proposed method for PAR detection in biological samples. Therefore, our combined electrochemical-colorimetric method provides a suitable point-of-care sensor for PAR determination, enabling a prompt and straightforward diagnosis to reduce mortality in intoxication cases.