Chemiluminescence data modeling using parallel factor analysis for the simple and sensitive determination of diphenoxylate in human plasma and tablets

In this study, a chemiluminescence (CL) method was developed to determine diphenoxylate in tablets and human plasma. This is the first CL method proposed to determine diphenoxylate. Creating three-dimensional data caused the parallel factor analysis algorithm (PARAFAC) to be used for the first time in CL methods. The method is based on the fact that diphenoxylate enhances the weak CL produced in the reaction of Ru(phen)3 2+ and acidic Ce(IV), and the concentration of Ce(IV) solution has a different effect on the CL response of diphenoxylate and the blank plasma. The calibration curve was linear from 4.0 × 10-8 to 1.6 × 10-6 mol L-1 (R2 = 0.9954), and the detection limit was 1.3 × 10-8 mol L-1 (S/N = 3). The sampling rate was about 30 samples per hour, and the % RSD for 10 repeated measurements of 4 × 10-7 mol L-1 diphenoxylate was 5.4%. The interference effects of some ions, amino acids, and common additives were also investigated. The CL method was successfully used to determine diphenoxylate in tablets, and the results were statistically confirmed by the reference method. The proposed CL method and the PARAFAC algorithm were successfully used to determine the concentration of diphenoxylate in human blood plasma samples.

Sensitive electrochemical assay of acetaminophen based on 3D-hierarchical mesoporous carbon nanosheets

Acetaminophen plays a key role in first-line Covid-19 cure as a supportive therapy of fever and pain. However, overdose of acetaminophen may give rise to severe adverse events such as acute liver failure in individual. In this work, 3D-hierarchical mesoporous carbon nanosheet (hMCNS) microspheres with superior properties were fabricated using simple and quick strategy and applied for sensitive quantification of acetaminophen in pharmaceutical formulation and rat plasmas after administration. The hMCNS microspheres are prepared via chemical etching of zinc oxide (ZnO) nanoparticles from a zinc-gallic acid precursor composite (Zn-GA) synthesized by high-temperature anaerobic pyrolysis. The obtained hMCNS could enhance analytes accessibility and accelerate proton transfer in the interface, hence increasing the electrochemical performance. Under optimized experimental conditions, the proposed electrochemical sensor achieves a detection limit of 3.5 nM for acetaminophen. The prepared electrochemical sensor has been successfully applied for quantification of acetaminophen in pharmaceutical formulations and the rat plasma samples before and after administration. Meanwhile, this sensor is compared with high-performance liquid chromatography (HPLC) as a reference technology, showing an excellent accuracy. Such an electrochemical sensor has great potential and economic benefits for applications in the fields of pharmaceutical assay and therapeutic drug monitoring (TDM).

Multiway resolution of spectrochromatographic measurements for the quantification of echinuline in marine-derived fungi Aspergillus chevalieri using parallel factor analysis

A multiway resolution of incomplete chromatographic separation was presented for spectrochromatographic quantification of echinuline in marine-derived fungi Aspergillus chevalieri. Two-dimensional spectrochromatographic maps of calibration, validation and real samples were recorded as a function of time and wavelength using UPLC-PDA instrument under non-optimized chromatographic conditions, which gave rise to co-elution of echinuline and the constituents of sample matrix. A three-way array was obtained by concatenating the data matrices of the spectrochromatographic maps. Then, parallel factor analysis was applied to the multiway array to extract the individual contribution of echinuline in three modes (time, wavelength and sample). While time and wavelength profiles were used for the characterization of echinuline, the sample profile was used for its quantitative determination of the analyte in validation set and in real samples. Validity of the analytical method was evaluated by analyzing the validation set, which consist of test samples, standard addition samples, intra-day and inter-day samples. The proposed multiway analysis method was then applied to marine-derived fungi extracts and echinuline content was found to be 31.9 µg/g based on the average of ten assay results. The assay results provided by PARAFAC model were statistically compared with those obtained by a newly developed classical UPLC method, which ensured the complete separation of echinuline in a run time of nine minutes. The assay results were found to be comparable due to the fact that there was no significant difference between the analysis results (F = 1.63, Fcrit = 3.17; t = 0.69, tcrit = 2.11) at the significance level of 95%). Consequently, the PARAFAC method permitted the accurate determination of echinuline in fungal extracts despite the partial chromatographic separation with a run time of only three minutes.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Determination of pholcodine in syrups and human plasma using the chemiluminescence system of tris(1,10 phenanthroline)ruthenium(II) and acidic Ce(IV)

Pholcodine is an opiate derivative drug which is widely used in pediatric medicine. In this study, a chemiluminescence (CL) method is described that determines pholcodine in human plasma and syrup samples. This method is based on the fact that pholcodine can greatly enhance the weak CL emission of reaction between tris(1,10 phenanthroline)ruthenium(II), Ru(phen)₃²⁺ , and acidic Ce(IV). The CL mechanism is described in detail using UV-vis light, fluorescence and CL spectra. Effects of chemical variables were investigated and under optimum conditions, CL intensity was proportional to the pholcodine concentration over the range 4.0 × 10^-8 to 8.0 × 10^-6  mol  L^-1 . The limit of detection (LOD) (S/N = 3) was 2.5 × 10^-8  mol  L^-1 . Percent of relative standard deviations (%RSD) for 3.0 × 10^-7 and 3.0 × 10^-6  mol  L^-1 of pholcodine was 2.9 and 4.0%, respectively. Effects of common ingredients were investigated and the method was applied successfully to the determination of pholcodine in syrup samples and human plasma.