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Iron present in hemolyzed plasma could cause the degradation of artemisinin by reductively cleaving the peroxide bridge of artemisinin during sample preparation, which is a significant technical challenge for artemisinin determination. In this paper, this issue was resolved by using sodium nitrite as methemoglobin-forming agent to oxidize hemoglobin to methemoglobin in the presence of acetic acid and prevent the degradation of artemisinin in hemolyzed plasma during the sample preparation procedure. Then, a high-performance liquid chromatography tandem high-resolution mass spectrometry method was developed and validated for the determination of artemisinin in normal and hemolyzed plasma. The linear range was validated over the concentration range of 5–500 ng ml−1. The matrix effect and stability were also evaluated. This robust and sensitive assay was successfully applied to a pharmacokinetic study in rats after an oral administration of Artemisia annua L. extract. 相似文献
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采用高效液相色谱-光电二极管阵列-高分辨质谱联用(HPLC-PDA-HRMS)技术对马鞭草中的主要化学成分进行分析和鉴定。通过综合分析所检测到化合物的色谱、一级和多级全扫描质谱数据,对马鞭草提取物中的化学成分进行分析鉴定。马鞭草提取物中检测到环烯醚萜苷类、黄酮类、三萜类、苯乙醇苷类和二萜酚类化合物等共21种化学成分,其中鼠尾草酸、鼠尾草酚、迷迭香酚、异迷迭香酚、迷迭香酸以及金合欢素-7-O-芸香糖苷6种化合物并未在其他有关马鞭草提取物鉴定的文献中出现。该方法简单快速,准确度高,为鉴定中药材真伪和品质提供了可靠的科学依据。 相似文献
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Although CdCu3Ti4O12 is isostructural to CaCu3Ti4O12, the room temperature low-frequency dielectric constant of the former compound was reported to be ∼400, only 1/25 of that of the latter material [M.A. Subramanian, et al., J. Solid State Chem. 151 (2000) 323]. In this communication, we report that the dielectric constant of CdCu3Ti4O12 can be remarkably increased by elevating the sintering temperature. The room temperature dielectric constant at 100 kHz achieves 9000, almost as much as that of CaCu3Ti4O12, for the sample sintered at 1283 K. The appearance of giant dielectric constant in CdCu3Ti4O12 is explained in terms of internal barrier layer capacitance (IBLC) effect with the subgrain boundary as the barrier. Our result supplies an approach in searching for new giant-dielectric-constant materials in the CaCu3Ti4O12 family. 相似文献
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Youtian Fu Ling Zhang Maolin Sun Liming Cao Lei Yang Prof. Dr. Ruihua Cheng Prof. Dr. Yueyue Ma Prof. Dr. Jinxing Ye 《European journal of organic chemistry》2023,26(35):e202300553
Due to the high oxidation potentials of electron-deficient aromatic hydrocarbons, it is difficult to achieve the direct oxidative C(sp2)−H bonds functionalizations of such substrates. Herein, we develop a Ritter-type amination of electron-deficient aromatics by merging electricity and sulfate. This practical and straightforward method provides a series of acetanilides from simple electron-deficient arenes, including mono-, di- and tri-substituted arenes (22 examples, up to 75 %) with moderate to good yields under mild conditions. This method is characterized by cheap and readily available regents, atom and step economy. 相似文献