Combined assay for phenacetin and paracetamol in plasma using capillary column gas chromatography-negative-ion mass spectrometry

Detection of paracetamol by a montmorillonite-modified carbon paste sensor: A study combining MC simulation, DFT computation and electrochemical investigations

This study aims to develop a suitable electrochemical electrode through the incorporation of potassium montmorillonite (MMTK10)clay into the carbon matrix for the direct and sensitive determination of paracetamol (PAR) in pharmaceutical formulations. Electrochemical characterization of the electrodes involves the use of techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The results reveal that the voltammetric response of PAR is linear over a wide concentration range (1.0-15 μM), with a low detection limit of 0.46 μM. Analytically, PAR recovery results were around 94%, indicating that the developed electrode is highly suitable for PAR detection in pharmaceutical formulation. Additionally, density functional theory (DFT) is employed to investigate the reactivity of PAR and explain the interaction process of PAR on the electrode surface at different pH values. A Monte Carlo simulations model is developed to provide a deeper understanding of the adsorption mechanism, particularly to comprehend molecular interactions and preferential orientations of PAR with MMT fractions at the electrode surface. Reduced Density Gradient is calculated and discussed using techniques such as Multiwfn and Visualization of Molecular Dynamics. The developed CPE-MMTK10 sensor provided a simple preparation method, rapid response, high sensitivity, reproducibility, strong selectivity, and extended stability. Moreover, there is a good correlation between most parameters calculated by DFT and experimental results, thereby reinforcing the validity of the theoretical approach in this study.

Sensitive and selective determination of paracetamol in antipyretic children's syrup with a polyglycine modified glassy carbon electrode

A sensitive and selective electrochemical sensor for the determination of paracetamol (acetaminophen) is proposed based on a polyglycine-coated glassy carbon electrode. The electrochemical behavior of paracetamol was studied by cyclic voltammetry and differential pulse voltammetry. Under optimal experimental conditions, the peak oxidation current of paracetamol increases linearly in the range of 0.5-75 μM. The limit of detection of paracetamol was 0.03 μM and the limit of quantitation was 0.09 μM. In addition, modified glassy carbon with polyglycine as the sensor was successfully used for the determination of paracetamol in antipyretic children's syrup samples, with a recovery rate of over 95.3%, showing its great application potential in drug analysis.

Simultaneous determination of dantrolene and paracetamol in human plasma by liquid chromatography tandem mass spectrometry

A simple, sensitive, rapid and specific method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the simultaneous quantification of dantrolene (DAN) and paracetamol (PAR) in real human plasma was developed and validated. The preparation of sample was achieved by liquid-liquid extraction with tertiary butyl methyl ether. The analysis was performed on a reversed-phase C₁₈column (1.7 µm, 2.1 × 30 mm) using acetonitrile: 0.1% formic acid (80:20, v/v) as the mobile phase and pumped in an isocratic mode at a flow rate of 0.3 mL/min using citalopram (CIT) as an internal standard. Tandem mass spectrometric detection was carried out by both positive and negative electrospray ionization (ESI) in the multiple-reaction monitoring mode (MRM). The analysis was carried out within 1 min for each sample which made it possible to analyze more than 350 human samples per day. Validation of the method was performed according to FDA guidelines for bio-analytical method. The method was found to be linear in the range of 25-2500 ng/mL and 100-10,000 ng/mL for DAN and PAR, respectively. The method was applied successfully for the determination of the two analytes in the plasma after oral administration of Dantrelax® compound capsules to healthy volunteers. The study was accomplished after approval of the ethics committee.

Corona discharge ionization of paracetamol molecule: peak assignment

Ionization of paracetamol was investigated using ion mobility spectrometry equipped with a corona discharge ionization source. The measurements were performed in the positive ion mode and three peaks were observed in the ion mobility spectrum. Experimental evidence and theoretical calculations were used to correlate the peaks to related ionic species of paracetamol. Two peaks were attributed to protonated isomers of paracetamol and the other peak was attributed to paracetamol fragment ions formed by dissociation of the N-C bond after protonation of the nitrogen atom. It was observed that three sites of paracetamol compete for protonation and their relative intensities, depending on the sample concentration. The ratio of ion products could be predicted from the internal proton affinity of the protonation sites at each concentration.

Determination of paracetamol in mouse, rat and dog plasma samples by laser diode thermal desorption--APCI-MS/MS

BACKGROUND

Laser diode thermal desorption (LDTD) is a relatively new sample introduction interface for MS. Analysis times are short as the technique does not require time-consuming separation steps, such as conventional HPLC, thus saving on the use of organic solvents, modifiers and cost, relating to their subsequent disposal. This paper compares the merits of LDTD-APCI-MS/MS and LC-MS/MS for the analysis of paracetamol (acetaminophen) in plasma from different species.

RESULTS

LDTD-APCI-MS/MS compared favorably with our existing high-throughput generic LC-MS/MS method giving improved data quality. LDTD-APCI-MS/MS assay performance in terms of accuracy and precision in mouse, rat and dog plasma were within our local acceptance criteria (±30%). Run times were reduced approximately tenfold, while saving approximately 200 ml of solvent per 96-well plate.

CONCLUSION

A rapid, sensitive and robust assay is reported. The method was successfully used for the analysis of spiked mouse, rat and dog plasma samples and the determination of oral pharmacokinetics. Reductions in electrical power and reagent consumption position LDTD as an environmentally 'green' bioanalytical method.

Determination of paracetamol: historical evolution

Paracetamol is a common analgesic and antipyretic drug that is used for the relief of fever, headaches and other minor aches and pains. Their determination in pharmaceuticals is of paramount importance, since an overdose of paracetamol can cause fulminating hepatic necrosis and other toxic effects. Many analytical methodologies have been proposed for the determination of paracetamol. The aim of the present study is to evaluate the utility of different techniques for quantification of paracetamol content in pharmaceutical formulations and biological samples.

Spectrophotometric Determination of Paracetamol in Urine with Tetrahydroxycalix[4]arene as a Coupling Reagent and Preconcentration with Triton X-114 Using Cloud Point Extraction

In the present paper, conventional spectrophotometry in conjunction with cloud point extraction-preconcentration were investigated as alternative methods for paracetamol (PCT) assay in urine samples. Cloud point extraction (CPE) was employed for the preconcentration of p-aminophenol (PAP) prior to spectrophotometric determination using the non-ionic surfactant Triton X-114 (TX-114) as an extractant. The developed methods were based on acidic hydrolysis of PCT to PAP, which reacted at room temperature with 25,26,27,28-tetrahydroxycalix[4]arene (CAL4) in the presence of an oxidant (KIO(4)) to form an blue colored product. The PAP-CAL4 blue dye formed was subsequently entrapped in the surfactant micelles of Triton X-114. Cloud point phase separation with the aid of Triton X-114 induced by addition of Na(2)SO(4) solution was performed at room temperature as an advantage over other CPE assays requiring elevated temperatures. The 580 nm-absorbance maximum of the formed product was shifted bathochromically to 590 nm with CPE. The working range of 1.5-12 microg ml(-1) achieved by conventional spectrophotometry was reduced down to 0.14-1.5 microg ml(-1) with cloud point extraction, which was lower than those of most literature flow-through assays that also suffer from nonspecific absorption in the UV region. By preconcentrating 10 ml sample solution, a detection limit as low as 40.0 ng ml(-1) was obtained after a single-step extraction, achieving a preconcentration factor of 10. The stoichiometric composition of the dye was found to be 1 : 4 (PAP : CAL4). The impact of a number of parameters such as concentrations of CAL4, KIO(4), Triton X-100 (TX-100), and TX-114, extraction temperature, time periods for incubation and centrifugation, and sample volume were investigated in detail. The determination of PAP in the presence of paracetamol in micellar systems under these conditions is limited. The established procedures were successfully adopted for the determination of PCT in urine samples. Since the drug is rapidly absorbed and excreted largely in urine and its high doses have been associated with lethal hepatic necrosis and renal failure, development of a rapid, sensitive and selective assay of PCT is of vital importance for fast urinary screening and antidote administration before applying more sophisticated, but costly and laborious hyphenated instrumental techniques of HPLC-SPE-NMR-MS.

Rapid liquid chromatographic assay for the determination of acetaminophen in plasma after propacetamol administration: application to pharmacokinetic studies

A simple method for the rapid estimation of acetaminophen in plasma is described here. p-Propionamidophenol was used as internal standard. The assay involved a single ethyl acetate extraction and liquid chromatographic analysis at a wavelength of 242 nm using a reversed-phase encapped column, with a mobile phase of acetonitrile and 0.005 M potassium dihydrogen phosphate adjusted at pH 3.00. The limit of quantitation of acetaminophen by this method was 0.05 microg ml(-1), only 0.1 ml of the plasma sample was required for the determination. The calibration graph was linear from 0.05 to 100 microg ml(-1). Intra and inter-day precision (CV) did not exceed 8.93%. Mean recoveries of 90.31% with a CV of 1.38% were obtained. Applicability of the method was demonstrated by a pharmacokinetic study in normal volunteers who received 2 mg propacetamol.

Rapid identification of 4-hydroxy-2-alkylquinolines produced by Pseudomonas aeruginosa using gas chromatography-electron-capture mass spectrometry

The 4-hydroxy-2-alkylquinolines and their N-oxides are secondary metabolites produced by Pseudomonas aeruginosa which inhibit the growth of a number of Gram-positive organisms including Staphylococcus aureus. To facilitate the identification of these compounds in biological fluids, we have developed a rapid profiling system based on gas chromatography-electron-capture mass spectrometry of the O-bistrifluoromethylbenzoyl derivatives. Using the technique, over twenty hydroxyalkylquinolines have been identified from a culture obtained from a strain of P. aeruginosa obtained from a patient with severe bronchiectasis.