Quantitative analysis of piroxicam using temperature-controlled ionic liquid dispersive liquid phase microextraction followed by stopped-flow injection spectrofluorimetry

Nitrogen-Doped Graphene-Based Sensor for Electrochemical Detection of Piroxicam, a NSAID Drug for COVID-19 Patients

Nitrogen-doped graphene (NGr) was synthesized by the hydrothermal method using urea as a reducing and doping agent for graphene oxide (GO). The crystalline structure of GO was revealed by the XRD intense peak recorded at 2θ = 11.4°, indicating that the interlayer distance within the structure was large (d = 0.77 nm), and the number of layers (n) was 9. Further, the transformation of GO in NGr also led to the decrease in the interlayer distance and number of layers (d = 0.387 nm; n = 3). As indicated by elemental analysis, the concentration of nitrogen in the NGr sample was 6 wt%. Next, the comparison between the performance of bare GC and the graphene-modified electrode (NGr/GC) towards piroxicam (PIR) detection was studied. Significant differences were observed between the two electrodes. Hence, in the case of bare GC, the oxidation signal of PIR was very broad and appeared at a high potential (+0.7 V). In contrast, the signal recorded with the NGr/GC electrode was significantly higher (four times) and shifted towards lower potentials (+0.54 V), proving the electro-catalytic effect of nitrogen-doped graphene. The NGr/GC electrode was also tested for its ability to detect piroxicam in pharmaceutical drugs (Flamexin), giving excellent recoveries.

The Influence of Ionic Liquids on the Effectiveness of Analytical Methods Used in the Monitoring of Human and Veterinary Pharmaceuticals in Biological and Environmental Samples-Trends and Perspectives

Recent years have seen the increased utilization of ionic liquids (ILs) in the development and optimization of analytical methods. Their unique and eco-friendly properties and the ability to modify their structure allows them to be useful both at the sample preparation stage and at the separation stage of the analytes. The use of ILs for the analysis of pharmaceuticals seems particularly interesting because of their systematic delivery to the environment. Nowadays, they are commonly detected in many countries at very low concentration levels. However, due to their specific physiological activity, pharmaceuticals are responsible for bioaccumulation and toxic effects in aquatic and terrestrial ecosystems as well as possibly upsetting the body's equilibrium, leading to the dangerous phenomenon of drug resistance. This review will provide a comprehensive summary of the use of ILs in various sample preparation procedures and separation methods for the determination of pharmaceuticals in environmental and biological matrices based on liquid-based chromatography (LC, SFC, TLC), gas chromatography (GC) and electromigration techniques (e.g., capillary electrophoresis (CE)). Moreover, the advantages and disadvantages of ILs, which can appear during extraction and separation, will be presented and attention will be given to the criteria to be followed during the selection of ILs for specific applications.

Piroxicam

A comprehensive profile of piroxicam including the nomenclatures, formulae, elemental composition, appearance, uses and applications. The methods which were utilized for the preparation of the drug substance and their respective schemes are outlined. The physical characteristics of the drug including the ionization constant, solubility, x-ray powder diffraction pattern, differential scanning calorimetry, thermal behavior and spectroscopic studies are described. The methods which were used for the analysis of the drug substance in bulk drug and/or in pharmaceutical formulations including the compendial, spectrophotometric, electrochemical and the chromatographic methods are reported. The stability, toxicity, pharmacokinetics, bioavailability, drug evaluation, comparison, in addition to compiled reviews on the drug substance are involved. Finally, more than four hundred and fifty references are listed at the end of this profile.

Magnetic dispersive solid-phase extraction based on graphene oxide/Fe3 O4 @polythionine nanocomposite followed by atomic absorption spectrometry for zinc monitoring in water, flour, celery and egg

BACKGROUND

Magnetic graphene oxide nanocomposite has been proposed as a promising and sustainable sorbent for the extraction and separation of target analytes from food matrices. Sample preparation based on nanocomposite presents several advantages, such as desired efficiency, reasonable selectivity and high surface-area-to-volume ratio.

RESULTS

A new graphene oxide/Fe₃ O₄ @polythionine (GO/Fe₃ O₄ @PTh) nanocomposite sorbent was introduced for magnetic dispersive solid-phase extraction and flame atomic absorption spectrometric detection of zinc(II) in water, flour, celery and egg. To fabricate the sorbent, an oxidative polymerization of thionine on the surface of magnetic GO was applied, while polythionine was simply employed as a surface modifier to improve extraction yield. The properties of the sorbent were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis, vibrating sample magnetometry and Fourier transform-infrared spectroscopy. The calibration curve showed linearity in the range of 0.5-30 ng mL^-1 . Limits of detection (S/N = 3) and quantification (S/N = 10) were 0.08 and 0.5 ng mL^-1 , respectively.

CONCLUSION

The method was applied for trace-level determination of Zn(II) in water and food samples, and its validation was investigated by recovery experiments and analyzing certified reference material. © 2018 Society of Chemical Industry.

Trace determination of chlorpheniramine in human plasma using magnetic dispersive solid-phase extraction based on a graphene oxide/Fe3O4@polythionine nanocomposite combined with high-performance liquid chromatography

Graphene oxide/Fe₃O₄@polythionine (GO/Fe₃O₄@PTh) nanocomposite was fabricated for magnetic dispersive solid-phase extraction and high-performance liquid chromatography-ultraviolent detection (HPLC) of chlorpheniramine in human plasma.

Ionic liquid phase microextraction combined with fluorescence spectrometry for preconcentration and quantitation of carvedilol in pharmaceutical preparations and biological media

BACKGROUND

Carvedilol belongs to a group of medicines termed non-selective beta-adrenergic blocking agents. In the presented approach, a practical and environmentally friendly microextraction method based on the application of ionic liquids (ILs) was followed by fluorescence spectrometry for trace determination of carvedilol in pharmaceutical and biological media.

METHODS

A rapid and simple ionic liquid phase microextraction was utilized for preconcentration and extraction of carvedilol. A hydrophobic ionic liquid (IL) was applied as a microextraction solvent. In order to disperse the IL through the aqueous media and extract the analyte of interest, IL was injected into the sample solution and a proper temperature was applied and then for aggregating the IL-phase, the sample was cooled in an ice water-bath. The aqueous media was centrifuged and IL-phase collected at the bottom of the test tube was introduced to the micro-cell of spectrofluorimeter, in order to determine the concentration of the enriched analyte.

RESULTS

Main parameters affecting the accuracy and precision of the proposed approach were investigated and optimized values were obtained. A linear response range of 10-250 μg I(-1) and a limit of detection (LOD) of 1.7 μg I(-1) were obtained.

CONCLUSION

Finally, the presented method was utilized for trace determination of carvedilol in commercial pharmaceutical preparations and biological media.