Chromatographia最新文献

Elvitegravir (ETV), drug substance, and its eleven process-related impurities have been identified and their structural identification study has been carried out with the aid of ¹H, ¹³C NMR, and ESI–LC–MS spectroscopic techniques. Plausible fragments were also proposed for each impurity to ascertain its structure. Simple, facile, and selective, stability indicating, mass spectrometry compatible HPLC method has been developed and subsequently validated with the validation parameters of specificity, LOD, LOQ, precision at LOQ, linearity, accuracy at LOQ to 120% levels, method precision, intermediate precision studies, and solution stability has also been established. This method encompasses a simple gradient mode of separation with mobile phases—(A) 0.1% trifluoroacetic acid in water and (B) 0.1% trifluoroacetic acid in acetonitrile, the mass sectrometric compatible mobile phase has been chosen for the identification of known, unknown and degradation impurities. To assess the nature of each impurity, whether they are either process-related or degradation-induced, an intensive stress study has also been conducted. From this degradation assessment, all the impurities have been classified as process-related. Further, the assessment of three different manufacturers samples was also executed to show the method applicability and comparison of quality of the different manufacturers drug, and thus this method shall be engaged as a quality inferring tool for the marketed sample.

Objective

In this study, we aimed to develop a headspace capillary gas chromatography method to quantify residual methanol, acetone, methylene chloride, diisopropyl ether, ethyl acetate, and n,n-dimethylformamide (DMF), in raw clobetasol propionate.

Methods

The headspace gas chromatography method employs a chromatographic column packed with 6% cyanopropylphenyl-94% dimethylpolysiloxane as the stationary phase. The column temperature program initiated at 40 °C, was held for 10 min, then ramped up at 10 °C per minute to 220 °C, and maintained for 1 min. Nitrogen served as the carrier gas at a flow rate of 4.84 ml/min. The injection port temperature was set at 140 °C; the flame ionization detector (FID) operated at 250 °C, and the headspace equilibrium temperature was maintained at 105 °C with a 30 min equilibration time.

Results

All six residual solvents exhibited complete separation, displaying strong linearity and achieving high recovery rates. Furthermore, the residual solvent levels in the six samples tested remained comfortably below the permissible limit.

Conclusion

Our method is accurate, reliable, rapid, and sensitive, making it well-suited for the detection of organic residual solvents in raw clobetasol propionate.

Graphical Abstract

Amides often exhibit poor solubility in common solvents, posing challenges to their efficient separation. However, the development of robust RP-HPLC methods becomes essential to overcome this limitation, enabling accurate and reliable separation, quantification and characterization of these compounds. An RP-HPLC–UV technique has been developed for evaluating N,N’-dibutylterephthalamide, N,N’-dimethylterephthalamide, N,N’-bis(2-hydroxyethyl)terephthalamide and terephthalic dihydrazide obtained through aminolytic depolymerization of polyethylene terephthalate waste. The data obtained has been analyzed to arrive at most appropriate values of essential parameters to obtain highly resolved HPLC chromatograms using odyssil C₁₈ column (4.6 × 250 mm, 5 μm) from Agela Technologies with a UV detector. Dimethyl formamide and dimethyl sulfoxide emerged as the most suitable mobile phases with an isocratic run of 10 min at a flow rate of 0.4 mL/minute. Effect of temperature and concentration on HPLC chromatograms was also investigated for N,N’-dibutylterephthalamide from 30 to 50 ℃ and 0.5 mg to 2.5 mg/10 mL of solvent, respectively. 1–2.5 mg/10 mL concentration was found to be most suitable with the column temperature of 40 ℃. Method validation consisted of linearity, intra- and inter-day precision, detection and quantitation limit. The validation experiments confirmed the precision of the present method, with RSD% and CV% values for both intra- and inter-day precision measuring below 1.9% and 0.5%, respectively. The method was linear in the range of 0.5–2.5 mg/10 mL solvent (R² = 0.98). Detection and quantitation limit were determined to be 1.32 and 4.02 mg/10 mL, respectively, for peak 1 and 0.90 and 2.75 mg/10 mL, respectively, for peak 2.

Marine fish oils (MFOs) have been known for their nutritional compounds, which benefit human health. MFOs contain various lipids which play an essential role in human nutrition. The objective of this research was to apply untargeted lipidomics analysis using liquid chromatography–high-resolution mass spectrometry (LC–HRMS) for the comprehensive identification of lipid compositions extracted from five different marine fishes, namely red snapper (Lutjanus campechanus (A1)), giant grouper (Epinephelus lanceolatus (A2)), baronang crochet (Siganus canaliculatus (B2)), white snapper (Lates calcarifer (C3)), skipjack tuna (Katsuwonus pelamis (D2)). More than 1000 lipid compounds from both positive and negative ionization modes could be detected in each MFO using LC–HRMS untargeted lipidomics analysis. Most lipids were dominated by triglycerides (TG) and diglycerides (DG) classes. Principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) could classify MFO samples in positive and negative ionization modes. Based on variable importance for projections (VIP) value, 15 differentiating lipid compounds were found to have an essential role as potential biomarkers in positive ionization mode. In contrast, ten differentiating lipid compounds were found in negative ionization mode. It can be concluded that untargeted lipidomics using LC–HRMS could be used as a powerful analytical technique for comprehensively identifying lipid compositions in MFO samples. It can be further used to identify the lipid compositions of other fish oil samples.

Polymer microspheres have received attention because of their excellent properties. In this work, a polymer matrix zwitterionic amino acid stationary phase was prepared. Polyglycidyl methacrylate divinylbenzene (PGMA-DVB) microspheres was used as the matrix and successful modification with L-phenylalanine by ring-opening reaction of epoxy groups on the surface of PGMA-DVB microsphere matrix. The stationary phase was characterized by scanning electron microscopy, Fourier-transform infrared spectra, and elemental analysis. The phenylalanine-modified stationary phase was used in RPLC/HILIC mixed-mode chromatography for the separation of alkylbenzenes, polycyclic aromatic hydrocarbons, phenols, nucleosides and nucleic acids and etc. as probes, respectively. The good spatial selectivity of the stationary phase was demonstrated by the separation of biphenyl isomers. The prepared stationary phase showed good stability in alkaline condition (pH = 10) and low swelling in organic solvent mobile phase. Meanwhile, the stationary phase also showed good performance in the separation of different vitamins (Rs > 5.3), and the separation and detection of PAHs in river water.

Neurotransmitters (NTs) play a crucial role in brain function and associated with various neurological and neuropsychiatric disorders. This study devised an optimized analytical method, using high-performance liquid chromatography (HPLC) with electrochemical detection (ECD), to concurrently assess homovanillic acid (HVA), epinephrine (E), norepinephrine (NE), serotonin (5-HT), 5-hydroxyindolacetic acid (5-HIAA), melatonin (MT), and dopamine (DA) in mouse brain tissue. The mobile phase composition was fine-tuned to achieve efficient separation of these compounds, with optimal conditions involving 5% acetonitrile, 10% methanol, and 85% aqueous phase containing phosphate buffer, citric acid, sodium dodecyl sulfate (SDS) and ethylenedinitrilotetraacetic acid (EDTA). The pH of the mobile phase was adjusted to 3.2. An amperometric module was employed for electrochemical detection, with potential optimization to enhance sensitivity. The developed method exhibited excellent linearity and sensitivity, with limit of detection (LOD) and limit of quantification (LOQ) values lower than nmol L⁻¹. The method was applied to an intracerebral microdialysis experiment in mice hippocampus, demonstrating the capability to monitor changes in NTs and their metabolites in response to systemic fluoxetine/atomoxetine administration. This study presents a reliable and sensitive analytical approach to investigating NTs dynamics, which could contribute to a deeper understanding of neurotransmission under normal and pathological conditions.