Chromatographia最新文献

Violae herba (Zihuadiding) is a common Chinese herbal medicine. The current Chinese Pharmacopeia (ChP) defines Viola yedoensis Makino as the sole plant origin and esculetin as its sole quality-marker (Q-marker). Esculetin, however, occurs in some counterfeits as well. This implies that current ChP criterion actually cannot recognize the counterfeits of V. yedoensis. The study thus created a specialized MS library using ultra-high-performance liquid chromatography with quadrupole-orbitrap tandem mass spectrometry (UHPLC-Q-Orbitrap-MS/MS) analysis. Through library-comparison, 36 compounds were putatively identified from V. yedoensis; especially, four isomers were successfully distinguished, that is, vitexin vs isovitexin and schaftoside vs isoschaftoside. The subsequent UHPLC-Q-Orbitrap-MS/MS semi-quantification suggested that the chemical contents of 36 compounds varied from 0.001 to 1.958% and the old Q-marker esculetin had high content (0.484 ± 0.028%). According to the relevant principles, flavonoid luteolin was proposed as the new and additional Q-marker. The proposal offers a preliminary evidence to recognize seven adulterations (or counterfeits) of V. yedoensis.

Helicobacter pylori (H. pylori) infection is one of the primary risk factors of peptic ulcer disease worldwide. Treatment of H. pylori with the conventional dosage form is often challenging due to the ineffective reach of the antibiotics to the inner layers of gastric mucosa, where the organism resides. This study developed an eco-friendly, stability-indicating RP-HPLC method to simultaneously estimate amoxicillin and tinidazole from mucoadhesive formulation targeting H. pylori infection. The mucoadhesive GRDDS formulation of antibiotics was developed with a goal of improving bioavailability at the gastric mucosa. The multivariate Box–Behnken design (BBD) was utilized to optimize chromatographic parameters. Independent variable such as ratio of mobile phase, flow rate, pH and injections volume were optimized using DoE, and analyzed using perturbation plots. A desirability of 0.981 was achieved for the optimized variables. The optimized method utilized methanol and phosphate buffer (25:75) at pH 6.3 as the mobile phase in an isocratic elution mode on a Luna ODS C18 column kept at 25 °C as the stationary phase. The method was linear from 0.25 to 20 µg/mL, for both the drugs with R² values of 0.9993 and 0.9997 for amoxicillin and tinidazole, respectively. This validated RP-HPLC technique demonstrated selectivity in the presence of possible degradation products and excipients present in the mucoadhesive GRDDS beads. The method was used for the determination of entrapment efficiency and in vitro release profile for tinidazole and amoxicillin in the mucoadhesive GRDDS formulation.

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Chitosan is a chiral polyglucosamine polysaccharide that selectively binds to S-enantiomer of ketorolac rather than R-enantiomer. In this paper, a novel chiral stationary phase was prepared by molecular imprinting of chitosan using racemic ketorolac as a template. This imprinting process resulted in a high enantioselectivity (59.66% ee and enantioselectivity coefficient of 2.6) as evaluated by the batch rebinding study. The prepared stationary phase enabled chiral resolution of racemic ketorolac when packed into a solid-phase extraction cartridge. Moreover, promising results were obtained when an HPLC column packed with the proposed stationary phase was tested for chiral separation. The selectivity factor (α) was calculated to be 5.3 indicating the enantioselectivity of the prepared stationary phase. The chromatographic resolution trials revealed a mixed hydrophilic interaction liquid chromatography (HILIC) and reversed-phase (RP) separation modes in addition to the imprinted cavities. These results showed that racemic compounds could be cheaper and more available templates for imprinting of enantioselective polymers for chiral stationary phases.

A selective and simple method was developed for the determination of four ethyleneamines (EAs), i.e., ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA), by reversed-phase ion-pair chromatography with ultraviolet detection. The method is based on the on-line complexation of EAs with a Cu(II) ion added to the mobile phase. The Cu(II) complexes with EAs (Cu(II)-EA complexes) were well separated on a reversed-phased column, using 1-octanesulfonate as an ion-pairing reagent. The concentrations of 1-octanesulfonate and acetonitrile in the mobile phase significantly influenced the retention times of EAs. The high concentration of the Cu(II) ion in the mobile phase resulted in the increase of the baseline noise. A mixture of acetonitrile and 50 mM acetate buffer at pH 5.5 (23:77, v/v) which contains 0.5 mM CuSO₄ and 20 mM 1-octanesulfonic acid sodium salt was used as the mobile phase. Cu(II)-EA complexes could be detected at 243 nm. The limits of quantification of EAs (S/N = 10) were 0.003 mM for EDA, DETA, and TETA and 0.01 mM for TEPA. The calibration curves were linear over three orders of magnitude of EA concentrations with high correlation coefficients (r² = 1.000). The proposed method was successfully applied to determine EAs in epoxy resin curing agents.

The potential of separation of the macromolecules in solution by focusing thermal field-flow fractionation is critically analyzed. The experimental conditions of the high-performance separations of particulate species by this technique were extensively studied in the past and are well determined. On the other hand, very scarce and contradictory knowledge exists on the effective use of focusing thermal field-flow fractionation for the separation of macromolecules in solution. An important requirement is to apply the sufficient relaxation time to establish the initial steady-state distribution of the sample across the separation channel thickness, as close to the accumulation wall as possible, otherwise a serious zone broadening and false retention may occur. The concentration of the fractionated sample solution should be minimal, but allowing an accurate detector response, to avoid the viscous fingering and Rayleigh–Taylor hydrodynamic instabilities, and it should not exceed the critical concentration at which the macromolecular chains begin to overlap. The important conditions which enable or limit such separations are discussed.

Combination treatment enhances efficacy, minimizes side effects, and improves convenience for patients with diverse treatment schedules. This compilation focuses on the simultaneous estimation of Miconazole nitrate (MNE), Mupirocin (MRN), and Mometasone furoate (MMT) using HPLC and HPTLC in an ointment which is wisely used combination for treatment of skin disorders. The optimized isocratic HPLC method consists of a C18 column, 0.02% triethylamine: methanol (15:85; % v/v), at a flow rate of 0.9 mL/min. The retention times were found to be 4.716 ± 0.082 min for MNE, 13.716 ± 0.188 min for MRN, and 2.241 ± 0.034 min for MMT using the developed method. The method was validated indetail and the quantification range found 20–180 µg/mL for both MNE and MRN and 1–9 µg/mL for MMT. In an alternative HPTLC method, toluene, ethyl acetate, and ethanol (10:3:2; v/v/v) were used as mobile phase on silica gel 60F254-coated aluminum sheets, with scanning at 240 nm. The MNE, MRN and MMT drugs spot eluted at Rf values of 0.65, 0.36, and 0.80, respectively. In-depth validation was performed and assessed statistically, including, specificity, precision, accuracy, reproducibility, and accuracy. The HPTLC method found linear in ranges of 1200–5200 ng/band for MNE and MRN, and 60–260 ng/band for MMT. Consequently, these developed chromatographic methods assessed according to green analytical principle and found sustainable. The developed methods can be effectively applied for the quantitative analysis of commercially available dosage forms.

Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic (PK) investigations in situations where venous blood sampling is logistically and/or ethically challenging. The aim of this study was to establish, validate and demonstrate the application of a DBS amoxicillin assay for PK studies in vulnerable populations. The matrix effect, process efficiency (84–104%) and recovery (85–110%) of the liquid chromatography–mass spectrometry (LC–MS/MS) assay for amoxicillin in DBS was determined at 1, 10 and 100 µg/mL, and three different haematocrits. Thermal stability studies of amoxicillin in DBS were performed and a bridging study comprising 26 paired plasma and DBS samples was conducted in four healthy individuals. The limits of detection and quantification were 0.02 and 0.05 µg/mL for plasma and DBS amoxicillin assays, respectively. Accuracy and interday precision of amoxicillin in DBS (0.1–100 µg/mL) were 88–103% and 4.5–9.2%, respectively. At room temperature (22 °C) and 4 °C, amoxicillin was stable in DBS for ≈4 and 26 h, respectively. There was no degradation of amoxicillin in DBS at −20 °C for > 6 months. When comparing DBS and plasma collected from healthy volunteers, the slope of the Deming regression was 0.74. Amoxicillin CL/F estimates from DBS and plasma concentration data were 40.8 and 30.7 L/h/70 kg, respectively; V/F was 43.2 and 37.4 L/70 kg, respectively. In conclusion, amoxicillin can be reliably assayed from DBS in research studies but may have limited application in therapeutic drug monitoring. Due to poor stability at room temperature, amoxicillin DBS samples should be promptly dried and placed in frozen storage.

Phosphorylation is one of the most common post-translational modifications of proteins. Recognition of phosphorylated peptides with high selectivity is an important prerequisite for the structural identification of protein phosphorylation. By the application of molecular imprinting technology, a kind of tyrosine-phosphorylated peptide imprinted particles was prepared by the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and “epitope” strategy that applied in tyrosine-phosphorylated peptides recognition. Phenylphosphonic acid was used as the dummy template of the phosphorylated angiotensin II, which was one of the natural tyrosine-phosphorylated peptides. After the template modified by hydrogen bond with ureidopropyl group on the surface of silica, the surface imprinted particles with controlled and imprinted shell were synthesized by radical polymerization with RAFT strategy. The imprinted particles were obtained after the peptide removed and dithioester group destructed under alkaline condition. The binding capacity of phenylphosphonic acid reached 0.198 mg g⁻¹ with imprinting factor (IF) as 2.70, while the binding capacity of phosphorylated angiotensin II reached 0.792 mg g⁻¹ with IF as 1.96, which were obviously higher than with IF of that without RAFT strategy. Furthermore, phosphorylated angiotensin II could be selectively recognized by the imprinted particles even in presence of angiotensin II without phosphorylated. The performance of the phosphopeptide recognition remained 92% after five cycles of adsorption and desorption. All these results demonstrated that the tyrosine-phosphorylated imprinted particles prepared by combing RAFT polymerization and “epitope” strategy are promising to achieve the phosphopeptide recognition with higher recognition ability, selectivity and reusability.