共查询到20条相似文献,搜索用时 574 毫秒
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Caiming Tang Caixing Tang Wei Zhan Juan Du Zhifang Wang Xianzhi Peng 《Journal of separation science》2013,36(16):2584-2592
LC‐MS/MS is currently the most selective and efficient tool for the quantitative analysis of drugs and metabolites in the pharmaceutical industry and in clinical assays. However, phase II metabolites sometimes negatively affect the selectivity and efficiency of the LC‐MS/MS method, especially for the metabolites that possess similar physicochemical characteristics and generate the same precursor ions as their parent compounds due to the in‐source collision‐induced dissociation during the ionization process. This paper proposes some strategies for examining co‐eluting metabolites existing in real samples, and further assuring whether these metabolites could affect the selectivity and accuracy of the analytical methods. Strategies using precursor‐ion scans and product‐ion scans were applied in this study. An example drug, namely, caffeic acid phenethyl ester, which can generate many endogenous phase II metabolites, was selected to conduct this work. These metabolites, generated during the in vivo metabolic processes, can be in‐source‐dissociated to the precursor ions of their parent compounds. If these metabolites are not separated from their parent compounds, the quantification of the target analytes (parent compounds) would be influenced. Some metabolites were eluted closely to caffeic acid phenethyl ester on LC columns, although long columns and relatively long elution programs were used. The strategies can be utilized in quantitative methodologies that apply LC‐MS/MS to assure the performance of selectivity, thus enhancing the reliability of the experimental data. 相似文献
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The high-performance liquid chromatographic (HPLC) retention characteristics of 21 benzodiazepine drugs and some of their metabolites have been examined on both silica and ODS-silica packing materials. Four HPLC systems have been considered and retention data are presented for the drugs on these systems. The correlation of retention data on the systems is considered with reference to the problem of identifying unknown benzodiazepines. 相似文献
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Identification and elucidation of the structures of metabolites play major roles in drug discovery and in the development
of pharmaceutical compounds. These studies are also important in toxicology or doping control with either pharmaceuticals
or illicit drugs. This review focuses on: new analytical strategies used to identify potential metabolites in biological matrices
with and without radiolabeled drugs; use of software for metabolite profiling; interpretation of product spectra; profiling
of reactive metabolites; development of new approaches for generation of metabolites; and detection of metabolites with increased
sensitivity and simplicity. Most of the new strategies involve mass spectrometry (MS) combined with liquid chromatography
(LC). 相似文献
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Nakamura M 《Biomedical chromatography : BMC》2011,25(12):1283-1307
Benzodiazepines are among the most frequently prescribed drugs due to their sedative, hypnotic, anxiolytic, muscle relaxant and antiepileptic properties. Because of the high consumption of benzodiazepines worldwide, this class of drugs and their metabolites are frequently present in both clinical and forensic cases. For these reasons, the analysis of benzodiazepines and their metabolites in biological fluids is of great interest to clinicians and forensic toxicologists. This paper reviews procedures for multi-analyte single-stage (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) using different mass analyzers for the screening, identification and/or quantification of drugs, poisons and/or their metabolites in blood, plasma, serum or urine published since 2001. Basic information about the biosamples assayed, work-up, LC column, mobile phase, ionization type, mass spectral detection mode, matrix effects and validation data for each procedure is summarized. The feasibility of using LC-MS(/MS) techniques to identify and quantify benzodiazepines and their metabolites is also discussed. 相似文献
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The 3,5-dichlorophenylcarbamates (2) of cellulose bearing a small amount of 3-(triethoxysilyl)propyl residues were synthesized by a one-pot process and immobilized onto a silica gel through intermolecular polycondensation of the triethoxysilyl groups. The obtained cellulose derivatives were characterized by (1) H NMR and elemental analysis (EA), and their recognition abilities were evaluated by high-performance liquid chromatography (HPLC). The cellulose derivatives containing about 1-5% of the 3-(triethoxysilyl)propyl residue were efficiently immobilized with a high chiral recognition ability. The immobilized chiral packing materials (CPMs) could be used with the eluents containing chloroform and tetrahydrofuran (THF), which cannot be used with the conventional coated-type chiral packing materials. By using these eluents, the chiral recognition for many racemates was improved. 相似文献
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Robert V. Smith 《Trends in analytical chemistry : TRAC》1984,3(7):178-181
The determination of drugs and metabolites in biological fluids (biopharmaceutical analysis) is becoming increasingly important in the pharmaceutical and biomedical sciences. Successful analyses require sensitivities at ppb-level or less, high selectivity, and minimal interferences from artifacts. Modern approaches to biopharmaceutical analysis rely principally on chromatographic and immunochemical methods. 相似文献
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The development and integration of microfabricated liquid chromatography (LC) microchips have increased dramatically in the last decade due to the needs of enhanced sensitivity and rapid analysis as well as the rising concern on reducing environmental impacts of chemicals used in various types of chemical and biochemical analyses. Recent development of microfluidic chip-based LC mass spectrometry (chip-based LC-MS) has played an important role in proteomic research for high throughput analysis. To date, the use of chip-based LC-MS for determination of small molecules, such as biomarkers, active pharmaceutical ingredients (APIs), and drugs of abuse and their metabolites, in clinical and pharmaceutical applications has not been thoroughly investigated. This mini-review summarizes the utilization of commercial chip-based LC-MS systems for determination of small molecules in bioanalytical applications, including drug metabolites and disease/tumor-associated biomarkers in clinical samples as well as adsorption, distribution, metabolism, and excretion studies of APIs in drug discovery and development. The different types of commercial chip-based interfaces for LC-MS analysis are discussed first and followed by applications of chip-based LC-MS on biological samples as well as the comparison with other LC-MS techniques. 相似文献
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采用甲基丙烯酸甲酯 (MMA)或MMA 亚乙基二甲基丙烯酸酯 (EDMA)在硅胶表面聚合的方法 ,制备生成了新型高分子覆盖型硅胶填料C或D。借助红外光谱、元素分析、尺寸排阻色谱和反相液相色谱分析对反应过程、覆盖程度、交联剂的影响和填料的色谱保留行为进行了评价和讨论。结果显示 ,在合成时可以通过控制聚合单体的量控制生成高分子层的厚度 ,而合成中加入交联剂可以改变填料表面的微孔构造。通过考察这种色谱填料的疏水性和对芳香族化合物的分离性能 ,认为其柱效和分离效果接近C18填料的性能。 相似文献
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Preparative-grade bonded β- and γ-cyclodextrin stationary phases were used as the packing material of liquid chromato-graphic analytical microcolumns. Although the resulting columns are characterized by relatively low efficiency, the high selectivity of the cyclodextrin phases nevertheless allows their successful use for the separation of different classes of isomeric compounds that are difficult to resolve on conventional LC stationary phases. Examples of baseline (or almost baseline) separations of a number of isomeric compounds, including isomeric polycyclic aromatic hydrocarbons, are presented to demonstrate the analytical potential of such columns. Retention behavior of the separated isomers is discussed based on the structure of the solute molecule and the possibility of its inclusion into the molecular cavity of cyclodextrin stationary phases. 相似文献
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Gerd Vanhoenacker Alberto Dos Santos Pereira Takashi Kotsuka Deirdre Cabooter Gert Desmet Pat Sandra 《Journal of chromatography. A》2010,1217(19):3217-3222
The performance of a polymeric stationary phase with reversed-phase properties (ET-RP1) was evaluated for LC separations at elevated temperature. The most significant observation was that the reduced plate height (h) decreased from 3.4 at 25 °C (optimal flow 0.5 mL/min) to 2.4 at 150 °C (optimal flow 2.5 mL/min) which is comparable to the efficiency obtained with silica-based reversed-phase columns of 4.6 mm ID operated at 0.8 mL/min. The phase showed no deterioration after long use at 150 °C within the pH range 1–9. Catalytic activity originating from the stationary phase material, e.g. as experienced on zirconium columns operated at elevated temperature, was absent. The performance of ET-RP1 is illustrated with the analysis of some pharmaceutical samples by LC and LC–MS. Operation at elevated temperature also allows to reduce the amount of organic modifier or to replace acetonitrile and methanol by the biodegradable ethanol. 相似文献
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Many pharmaceutical compounds have electroactive groups and are readily measurable and detectable by liquid chromatography with electrochemical detection (LC–EC). LC–EC techniques have many advantages as measurement systems and new materials have been developed for working electrodes. Use of modern electroanalytical techniques for detection in LC of pharmaceutical compounds is discussed in this review. EC detection in LC often results in improved selectivity and detection limits for electroactive pharmaceutical compounds. Selected literature on the determination of pharmaceutical compounds in their dosage forms and in biological samples are reported. 相似文献
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Summary The procedure of polymer coating of preferably inorganic porous particle support materials for LC has been applied to the
preparation of a new type of weak cationexchange phases. A special copolymer of butadiene and maleic acid could be immobilized
on silica by cross-linking effected with radical starters such as peroxides or γ-radiation.
The chromatographic properties of such materials proved to be excellent regarding efficiency, ion-exchange capacity and selectivity,
as well as chemical stability also in comparison to other, commercially available, materials. Test measurements were successfully
performed with ionic or ionizable inorganic and organic solutes over the entire applicable pH-range of the mobile phase which
also contained organic modifiers. A special feature of the new type of cation-exchange phase is the minor contribution of
hydrophobic (lipophilic) interaction to the retention mechanism besides the actual ion-exchange process. 相似文献
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Tian Liu Fuying Du Yakun Wan Fanping Zhu Jie Xing 《Journal of mass spectrometry : JMS》2011,46(8):725-733
Artemisinin drugs have become the first‐line antimalarials in areas of multi‐drug resistance. However, monotherapy with artemisinin drugs results in comparatively high recrudescence rates. Autoinduction of CYP‐mediated metabolism, resulting in reduced exposure, has been supposed to be the underlying mechanism. To better understand the autoinduction of artemisinin drugs, we evaluated the biotransformation of artemisinin, also known as Qing‐hao‐su (QHS), and its active derivative dihydroartemisinin (DHA) in vitro and in vivo, using LTQ‐Orbitrap hybrid mass spectrometer in conjunction with online hydrogen (H)/deuterium (D) exchange high‐resolution (HR)‐LC/MS (mass spectrometry) for rapid structural characterization. The LC separation was improved allowing the separation of QHS parent drugs and their metabolites from their diastereomers. Thirteen phase I metabolites of QHS have been identified in liver microsomal incubates, rat urine, bile and plasma, including six deoxyhydroxylated metabolites, five hydroxylated metabolites, one dihydroxylated metabolite and deoxyartemisinin. Twelve phase II metabolites of QHS were detected in rat bile, urine and plasma. DHA underwent similar metabolic pathways, and 13 phase I metabolites and 3 phase II metabolites were detected. Accurate mass data were obtained in both full‐scan and MS/MS mode to support assignments of metabolite structures. Online H/D exchange LC‐HR/MS experiments provided additional evidence in differentiating deoxydihydroxylated metabolites from mono‐hydroxylated metabolites. The results showed that the main phase I metabolites of artemisinin drugs are hydroxylated and deoxyl products, and they will undergo subsequent phase II glucuronidation processes. This study also demonstrated the effectiveness of online H/D exchange LC‐HR/MSn technique in rapid identification of drug metabolites. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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N. C. Gillott M. R. Euerby C. M. Johnson D. A. Barrett P. N. Shaw 《Chromatographia》2000,51(3-4):167-174
Summary The capillary electrochromatographic (CEC) separation of a range of pharmaceutical bases was investigated on a commercially
available silica stationary phase using aqueous mobile phases. The effects of mobile phase composition, buffer pH, applied
voltage, and buffer anion on the retention behaviour of these bases were studied. Promising chromatography was obtained at
pH 7.8 but was later found to be irreproducible. However, successful and reproducible chromatography of the bases was achieved
at pH 2.3.
We have previously demonstrated that the addition of mobile phase additives such as TEA-phosphate at low pH values has resulted
in excellent CEC analysis of bases on reversed-phase packing materials. The same approach was applied to the analysis of bases
on the silica phase in order to improve peak shape. Excellent chromatography was obtained for the analysis of strong pharmaceutical
bases such as benzylamine, nortriptyline and diphenhydramine.
The experimental investigations have shown that the CEC separation of a range of pharmaceutical bases can routinely be achieved
with excellent peak shapes and peak efficiencies as high as 320,000 plates m−1. 相似文献
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杂化硅胶整体材料研磨法制备混合型高效液相色谱固定相 总被引:1,自引:0,他引:1
以聚乙二醇(PEG)为致孔剂,四甲氧基硅烷(TMOS)和乙烯基三甲氧基硅烷(VTMS)为杂化硅胶前驱体,在乙酸催化作用下使硅烷发生水解,在尿素加热分解提供的碱性环境下水解的硅烷进一步缩聚得到杂化硅胶整体材料。将此整体材料用球磨机研磨,然后用三羟甲基氨基甲烷处理,并洗涤干燥得到粒径为3 μm左右的硅胶颗粒。探索了不同反应条件对硅胶颗粒的大小、比表面积和孔径、表面形貌和分散性的影响;当TMOS和VTMS体积比为3:1时可以得到孔径为7.5 nm和比表面积为245 m2/g的硅胶颗粒。通过对所制得的硅胶颗粒表面进行C18(十八烷基二甲基氯硅烷)键合修饰和巯基-烯点击反应,得到混合型高效液相色谱固定相。对此固定相的测试结果表明以上硅胶色谱填料的制备方法具有一定的实用性。 相似文献
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The C7N aminocyclitol family of natural products 总被引:1,自引:0,他引:1
Mahmud T 《Natural product reports》2003,20(1):137-166
This review covers microbial secondary metabolites classified in the family of C7N aminocyclitols, a relatively new class of natural products that is increasingly gaining recognition due to their significant biomedical and agricultural uses. Their discovery and structure determinations, their biosynthetic origin, biological properties, chemical synthesis, as well as their further development for pharmaceutical uses are described. The literature from 1970 to July 2002 is reviewed, with 269 references cited. 相似文献