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《Electrophoresis》2018,39(16):2144-2151
The chromatographic behavior of new biogenic purine nucleosides in hydrophilic interaction liquid chromatography was examined on three different stationary phases, namely bare silica, and amide‐ and cyclofructan‐based stationary phases. The effects of buffer concentration, pH and acetonitrile‐to‐aqueous‐part ratio in the mobile phase on retention and peak shape were assessed. The retention coefficients and peak symmetry values substantially differed with respect to analytes´ structures, stationary phase properties and mobile phase composition. The bare silica column was unsuitable for these compounds under the chromatographic conditions tested due to very broad and asymmetrical peaks. Furthermore, the cyclofructan‐based stationary phase provided almost Gaussian peak shapes of all deazapurine nucleosides under most conditions tested. Therefore, the cyclofructan‐based stationary phase is the most suitable choice for the chromatographic analysis of nucleosides. 相似文献
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提出了一种基于微分法的峰值检测电路,它包含微分电路、双沿触发比较器和采样保持电路。微分电路对输入信号进行微分变换,双沿触发比较器比较微分变换结果与参考电压,得到采样保持控制信号,以控制采样保持电路的正常工作,实现峰值检测功能。该检测电路具有高频率、高精度的特点,工作频率达到200~500 MHz,峰值检测误差小于5%。该检测电路适用于高速A/D转换器、D/A转换器和具有复杂参数的采集系统等领域。 相似文献
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Automated peak tracking for comprehensive impurity profiling in orthogonal liquid chromatographic separation using mass spectrometric detection 总被引:1,自引:0,他引:1
The presence and quantity of impurities in pharmaceutical drugs can have a significant impact on their quality and safety. With the continuous pressure for increased industry productivity, there is urgent need for a systematic and comprehensive drug impurity profiling strategy. We report here our development of the fully automated Comprehensive Orthogonal Method Evaluation Technology (COMET) system. The system includes five columns, seven orthogonal HPLC methods, and hyphenated UV-MS detections, which provides automated generic impurities screening for any drug sample. An automated MS peak tracking approach by program-based mass spectral interpretation is devised to unambiguously track impurities among all orthogonal HPLC methods. The program passes electro-spray ionization mass spectra (ESI-MS) through four sequential decision-making mass ion tests and determines molecular weights for every peak. The system reduces the time required to obtain impurity profile from weeks to days, while the automated MS peak tracking takes only minutes to interpret all MS spectral data of interest. Up-to-date, impurity contents of 56 in-development drug candidate samples have all been successfully illustrated by COMET, which contained more than 500 chemical entities. The program is able to track more than 80% of the compounds automatically with majority of the failure due to insufficient ionization for some impurities by ESI. This system is well suited for efficient drug development and ensuring the quality and safety of drug products. 相似文献
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