Electrochemical Kinetics and Detection of Paracetamol by Stevensite-Modified Carbon Paste Electrode in Biological Fluids and Pharmaceutical Formulations.

Paracetamol (PCT), or acetaminophen, is an important drug used worldwide for various clinical purposes. However, the excessive or indiscriminate use of PCT can provoke liver and kidney dysfunction; hence, it is essential to determine the amount of this target in biological samples. In this work, we develop a quick, simple, and sensitive voltammetric method using chemically modified electrodes to determine PCT in complex matrices, including human serum and commercial solid formulations. We modify the carbon paste electrode with stevensite monoclinic clay mineral (Stv-CPE), using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy to characterise and detect PCT. The kinetics study provides a better electrochemical characterisation of the electrode behaviour, finding the detection and quantitation limits of 0.2 µM and 0.5 µM under favourable conditions. Further, the best linear working concentration range is 0.6-100 µM for PCT, applying the proposed method to the quantitative determination of PCT content in reference tablet formulations and biological samples for validation.

Development and Validation of an RP-HPLC-PDA Method for Determination of Paracetamol, Caffeine and Tramadol Hydrochloride in Pharmaceutical Formulations.

Paracetamol (acetaminophen) (PAR), caffeine (CAF) and tramadol hydrochloride (TRA) are important drugs widely used for many clinical purposes. Determination of their contents is of the paramount interest. In this respect, a quick, simple and sensitive isocratic RP-HPLC method with photodiode array detection was developed for the determination of paracetamol, caffeine and tramadol in pharmaceutical formulations. An improved sensitive procedure was also evolved for tramadol using a fluorescence detector system. A C18 column and a mobile phase constituted by methanol/phosphate were used. LODs were found to be 0.2 µg/mL, 0.1 µg/mL and 0.3 µg/mL for paracetamol, caffeine and tramadol hydrochloride, respectively, using photodiode-array detection. Alternatively, LOD for tramadol decreased to 0.1 µg/mL with the fluorescence detector. Other notable analytical figures of merit include the linear concentration ranges, 0.8-270 µg/mL, 0.4-250 µg/mL and 1.0-300 (0.2-40) µg/mL, for the same ordered analytes (including the fluorescence detector). The proposed method was successfully applied for the quantitative determination of the three drugs in tablet dosage forms.