Chromatographia最新文献

The possibility of applying the system: weakly basic Amberlite IRA-68 resin-nitrilotriacetic acid (NTA) solutions for the separation of rare earth elements (REE) by ion exchange chromatography was investigated. Preliminary research results revealed that the affinity of REE towards the ion exchanger is closely correlated with the stability of their negative complexes that they form with NTA. Three separate groups of lanthanides could be distinguished, i.e. light (La, Ce, Pr, Nd), medium (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er) and heavy (Tm, Yb, Lu, Sc). Moreover, it seemed that within the first and third groups it was possible to individually separate elements from each other. Based on the experimentally obtained relationships, the theoretically assumed course of the ion exchange reaction of anionic REE complexes with NTA on the Amberlite IRA-68 resin was confirmed. The influence of the ion exchanger particle size, column size and composition of the mobile phase, i.e. pH, NTA and neutral salt (NaNO₃) concentration, on the chromatographic separation of REE was investigated. It has been shown that the proper selection of these parameters makes it possible not only to divide REE into the three groups mentioned above, but also to individually separate some elements, i.e. La, Ce, Pr, Nd, Tm, Yb, Lu and Sc.

New comb-like polyelectrolytes with triethylammonium (pAUTEA-Br), N-methyl-piperidinium (pAUMP-Br), N-methyl-morpholinium (pAUMM-Br) and pyridinium (pAUPy-Br) cation groups were first used to separate steroid hormones, biogenic amines and amino acids under capillary electrophoresis conditions. The polymers acted as modifiers of electrophoretic systems and were used as dynamic coatings of inner surface of fused-silica capillary and additives to background electrolyte to perform capillary electrochromatography and micellar electrokinetic chromatography regimes, leading to increase in separation selectivity and efficiency, and as reagents for indirect spectrophotometric detection of amino acids. New materials also showed activity during on-line preconcentration of biogenic amines and reduced their limits of detections by 10 times. Thus, new comb-like polyelectrolytes were demonstrated to act as multifunctional materials for capillary electrophoresis. This study discusses the features of the influence of the polyelectrolytes on electrophoretic separation capabilities and their possibilities in separation of model biologically active substances. Modifiers of this type significantly expand the analytical capabilities of the capillary electrophoresis method.

A rapid rise in population has led to the exploitation of natural resources, especially medicinal plants to meet human needs. Repeated harvesting of non-renewable or slow growing plant parts can severely damage plant systems. The whole plant of Cyanthillium cinereum (Sahadevi) is the key ingredient in numerous extract-based commercial herbal formulations beneficial for skin and hair related diseases. Although, the official crude drug Sahadevi covers the whole plant of Cyanthillium cinereum but many reports focus on individual parts as well. This study conducts a systematic comparative chemical investigation using fingerprint and marker based study of different parts (root, stem, leaves and flower) collected from both low land (Indo-gangetic plain) and high altitude regions, comparing then with the whole plant to determine which portion contribute most to the plant’s chemical composition. We employed, multivariate tools including principal component analysis and hierarchical clustering analysis on the fingerprint data for similarity analysis. The results indicate a close chemical similarity between the leaf and flower samples of Cyanthillium cinereum with whole plant based on comparable lupeol content and chemical profile. The high similarity observed in the leaves suggests that they may be used as a substitute for the whole plant, supporting efforts to enhance the plant’s life expectancy. Additionally, this study concluded that samples collected from lowland areas contain a higher concentration of bioactive component than those from high-altitude regions.

Moxidectin (MOX) is a macrocyclic lactone which belongs to milbemycin family of antiparasitic endectocides. MOX is widely used in veterinary medicine for the treatment and control of external and internal parasites, MOX is also used for the treatment of onchocerciasis (river blindness) in humans. In this paper, MOX drug substance was subjected to acidic, alkaline, oxidation, thermal (solid and solution state), and photolytic (solid and solution state) stress degradation. Stress-degraded samples of MOX were analyzed by a reversed phase ultra performance liquid chromatography (RP-UPLC) method using HALO C18 column (100 × 2.1 mm, 2 µm). MOX and all major DPs were adequately separated by a gradient elution using 0.1% formic acid in water as mobile phase-A and acetonitrile as mobile phase-B. Total 12 major DPs, including seven new DPs (2-carboxyl-19-hydroxyl, 2-carboxyl-3,4-epoxy-19-hydroxyl, 14,15-epoxide, 26,27-epoxide, 14-OOH, 15-OOH, and 27-OOH) not previously reported in the literature, were observed. Structural characterization of these DPs was performed using UPLC-high resolution mass spectrometry (HRMS) and by comparison of their fragmentation profile with parent compound. Six major DPs namely 3,4-epoxide, 14,15-epoxide, 26,27-epoxide, 14-OOH, 15-OOH, and 27-OOH were isolated and purified from the stressed samples using semi-preparative HPLC. The chemical structures of these DPs were further confirmed through comprehensive nuclear magnetic resonance (NMR) spectroscopy studies. The study results reported in this paper should be helpful to further understand degradation pathways of MOX under different conditions. These results are also beneficial to facilitate quality monitoring of MOX drug substance as well as identification of unknown degradation products in drug formulations made with MOX drug substance.

Sickle cell disease is a genetic disorder treated with Voxelotor (Vox), the first hemoglobin oxygen-affinity regulator. Although Vox recently received expedited approval in the United States for the sickle cell disease therapy for certain age groups, no monograph is yet available in the official compendia for Vox. Therefore, current study aims to develop a stability-indicating HPLC method for determining five potential impurities in Vox drug substance. The procedure was developed by implementing principles of analytical quality by design (AQbD). A detailed risk evaluation was conducted in accordance with the cause-and-effect relationship. A factorial design was employed to identify the impact of the critical method parameters (CMPs) and their relationship to critical quality attributes (CQAs). The full factorial design was utilized and final method was optimized. The p-values of the model and lack of fit were < 0.0001 and > 0.05, respectively, indicating the best-fit statistical model for the studied responses. The CMPs, such as gradient slope (ratio of mobile phase-B % and gradient time), flow rate of 1.0 mL min⁻¹, and column oven temperature of 40 °C, were optimized from the full factorial design. The best possible separation among all impurities and Vox was achieved with gradient elution using X-Bridge C₁₈, 150 mm × 4.6 mm, 3.5 µm analytical column. The optimized gradient is time (min)/%B: 0.0/15, 3.0/15, 20.0/80, 30/80, 31/15, 35/15. The peak pairs where the separation was highly critical were: impurity-4/impurity-5 and impurity-5/Vox. Method validation, revealed that the mean recovery of the impurities ranged between 100 and 106%, the correlation coefficient (r) > 0.99, across the span for LOQ–150% levels, RSD values (n = 6) ranged between 1.2 and 4.6% for 100% level (i.e., 0.1% of impurities). The peaks from the specificity analysis did not intervene with the known and active analyte (Vox) peak and this study identified impurity-2 as a major degradation product.

DM1, a derivative of maytansine, is the payload of trastuzumab emtansine (T-DM1). In this work, a new gradient reverse-phase ultra-performance chromatographic (RP-UPLC) method was proposed for analysis of five structural analogues (DM1-2, AP-3, DM1-4D, DM1-3D, and DM1-3L) of DM1. The chromatographic separation was accomplished by using a Waters BEH Phenyl column (50 × 2.1 mm, 1.7 μm), at the wavelength of 252 nm. Validation of the method was carried out according the ICH guidelines in terms of specificity, accuracy, precision, linearity and robustness. The developed method was proved to be convenient and reliable for quantitative determination of the DM1 analogue impurities. It can also be used for the related substances determination in DM1 bulk samples.

In this paper, a mixed-mode monolith was prepared by separately synthesizing hydrophilic and hydrophobic materials at both ends of a chromatography column by a one-step method. The prepared mixed mode monolith was used as solid phase extraction adsorbent for simultaneous enrichment and purification of licorice chalcone A and isoliquiritigenin from licorice combined with high performance liquid chromatography (HPLC). It had superior ability to enrich and purify licorice chalcone A and isoliquiritigenin than single hydrophilic or hydrophobic monolith. The method had good linearity in the range of 0.50–400 μg/mL. The linear regression equation was y = 465.45 ×  − 1.04 and the correlation coefficient was 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day precision were both less than 1.19%. The results showed that the method was simple and accurate, and could be used for the enrichment and purification of licorice chalcone A and isoliquiritigenin from licorice.

As a new carbon nanomaterial, graphene (Gr) has attracted wide attention in the field of separation and analysis because of its large specific surface area and strong hydrophobicity. A highly efficient and selective graphene/SiO₂ (Gr/SiO₂) dispersive solid-phase extraction (d-SPE) material was prepared through electrostatic assembly. This process involved the combination of negatively charged poly (sodium 4-styrenesulfonate) (PSS) mediated GS (denoted as PSS-GS) and positively-charged SiO₂, modified with triethoxy silane amino. The precursor material was characterized using FESEM, FTIR and so on. We evaluated the extraction performance of this new sorbent with eight pesticide residues, using the HPLC–MS method. The sorbent demonstrated excellent recovery rates for the pesticide residues under various frequency of use conditions and pH levels. It showed that the SiO₂ and Gr have synergistic extraction effect, and the composite material has good stability and reusable, Ultimately, this newly developed d-SPE material was successfully applied in the analysis of fruit juice samples, yielding good recovery rates in the range of 82.18 to 117.49%.

Melia. toosendan Sieb.et Zucc., a potent herbal medicine, boasts diverse therapeutic properties. As the main components, the isotoosendanin blocks protective autophagy in chemotherapy-induced cultured cancer cells and xenograft tumor tissue to significantly enhancing anticancer activity, and the fraxinellone contributes to pesticidal activity, anti-inflammatory and immunomodulatory effects. Until now, the metabolic profiles remained unknown. In the present study, 13 metabolites of isotoosendanin and 13 metabolites of fraxinellone were characterized in the blood, urine, and feces of rats by UPLC/ESI/qTOF-MS analysis. Five metabolites (F-M3, F-M5, I-M1, I-M5, I-M8) were fully characterized. The isotoosendanin and fraxinellone were mainly involved in hydrogenation, acetylation, and methylenation metabolic reactions. This is the first study illuminates the two components in vivo metabolism, laying the foundation for future pharmacodynamic and mechanistic investigations. It is necessary to deeply understand the process of drug activation, and deactivation, rationally design new drugs, and guide the research and development of new drugs.

Restricted Access Media-Methacrylic Resin with the ability of protein exclusion was prepared by the free radical polymerization using methacrylic acid, ethylene glycol dimethacrylate and glycidyl methacrylate as monomer, cross-linker and comonomer, respectively. Protein exclusion ability of this material was studied. The results showed that the material was able to eliminate 93.6% of protein after bovine serum albumin solution was added and shaken for 220 min. Adsorption kinetics and adsorption isotherms of Lamotrigine on this material were investigated. The experimental data were the most suitable for the pseudo-second-order kinetics model and Freundlich isotherm model. Restricted Access Media-Methacrylic Resin was used as sorbent for Solid-Phase Extraction to extract Lamotrigine from Human Plasma. The method for the determination of Lamotrigine in human plasma by SPE followed by the HPLC–UV presented linear range from 1.0 to 66.6 µg/mL with correlation coefficient 0.9930 for Lamotrigine, assay precision with relative standard deviation value 6.24%, and assay accuracy 94.7–104.7% with relative standard deviation values 4.33–5.81%. SPEs filled with this material were used at least 7 times without any significant changes in their performance. Analytical validation parameters demonstrated that the method could be applied to the determination of Lamotrigine at the therapeutic plasma levels without other treatments.