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脯氨酸类衍生物结构独特,鲜有报道利用核磁共振(nuclear magnetic resonance,NMR)技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱(1H-1H COSY)、1H-1H质子全相关谱(1H-1H TOCSY)、1H-1H核Overhauser效应谱(1H-1H NOESY)、13C NMR、无畸变的极化转移增强法(DEPT135°)、1H-13C检出1H的异核单量子相干(1H-13C HSQC)和1H-13C检出1H的异核多键相关(1H-13C HMBC),对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜(DMSO)中L型和D型的顺反异构体以相同的比例同时存在. 相似文献
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采用^1H NMR谱、^13C NMR谱、DEPT(θ=3π/4)谱、红外吸收光谱、质谱等仪器分析手段确证了4种新合成的有机光致变色材料螺E嗪化合物的结构,并对化合物的^13C NMR谱化学位移和质谱碎片进行了归属和确认。 相似文献
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采用核磁共振氢谱(~1H NMR)、选择性一维全相关谱(1D-TOCSY)及定量核磁共振法(qNMR)对液态乳中的1,2-丙二醇进行了快速筛查及含量测定,并与气相色谱法的测定结果进行了比较。~1H NMR法以液态乳基质中1,2-丙二醇的甲基质子信号特征为初步定性标准,选择性一维全相关谱法以1,2-丙二醇的亚甲基和次甲基质子信号特征为精确定性标准。在定性检测基础上,采用定量核磁共振法以1,2-丙二醇δ 1.15处的质子峰为定量峰,3-(三甲基硅基)氘代丙酸钠(TMSP)δ 0.00处的峰为内标峰,测定了液体乳中1,2-丙二醇的绝对含量。方法的检出限为0.002 mg/mL,定量下限为0.006 mg/mL。实际样品测定结果显示,NMR法与气相色谱法的检测结果一致,且NMR法前处理简单,操作方便,专属性高,在提高检测效率的同时能够避免假阳性结果出现,非常适合实际检测中液体乳中1,2-丙二醇的批量、快速检测。 相似文献
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对合成的莫达非尼试验品用液相色谱(HPLC)鉴定其纯度后,同时进行元素(EMA)、红外光谱(IR)、紫外光谱(UV)、质谱(MS)、差热()DTA)、核磁共振(NMR)氢谱及碳谱分析,根据分析的结果进行解析,确证了其化学结构为莫达非尼。 相似文献
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利用固相萃取分离和核磁共振技术(nuclear magnetic resonance,NMR)对人体尿液中的代谢物进行了较为系统的研究。通过对人体尿液样品固相莘取后分离得到的五个组分^1H NMR,同核二维氢谱(correlation spectroscopy,COSY)和全相关谱(total correlation spectroscopy,TOCSY),异核相关光谱(heteronuclear single quantum correlation,HSQC和Heteronuclear muptiple bond correlation,HMBC),J-分解谱(J-resolved spectroscopic,J-RES)的谱图分析,解析出了74种化合物的^1H和^13C化学位移,并对一维^1H谱的多数谱峰进行了有效指认。 相似文献
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核磁共振波谱法测定药物基准物质的绝对含量 总被引:9,自引:0,他引:9
探讨在新药基准物质的确定过程中,利用核磁共振法测定药物绝对含量的可行性。以环丙沙星、安妥沙星、卡德沙星、加替沙星、左氧氟沙星、氧氟沙星、诺氟沙星、依诺沙星和洛美沙星9种喹诺酮类抗生素化学对照品为例,其中安妥沙星和卡德沙星为国家一类新药。采用重水、氘代二甲基亚砜或氢氧化钠的重水溶液为溶剂,对苯二酚或顺丁烯二酸为内标,用喹诺酮母核上的质子峰进行定量,以内标法和外标法计算含量。核磁共振法测定结果与各对照品标签示值的误差约为1%,内标法和外标法的计算结果一致。该方法专属、准确、简便、快速,适用于对药物基准物质绝对含量的测定。 相似文献
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采用定量核磁共振波谱法(qNMR)测定六硝基六氮杂异伍兹烷(CL-20)标准物质中有机杂质的含量。核磁谱图解析证明,主要有机杂质成分为残余溶剂乙酸乙酯和中间体五硝基-乙酰基六氮杂异伍兹烷(MPIW),以不含四甲基硅烷(TMS)的氘代丙酮为溶剂,将六甲基二硅醚的四氯化碳标准溶液加入待测液中作为内标,以其谱峰(δ=0.06)作为内标峰对两种有机杂质进行定量分析。考察了延迟时间和采样次数对准确定量的影响,结果显示为确保定量结果的准确性,延迟时间D_1应不小于20 s,采样次数为32次。采用优化后的实验参数进行纯度分析,测得CL-20标准物质中有机杂质乙酸乙酯和MPIW的质量分数分别为0.03516%和0.156 2%,相对标准偏差(RSD)分别为0.91%和0.86%。 相似文献
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Summary A gradient programmed reversed phase high-performance liquid chromatographic (RP-HPLC) method is described for the quantitative
determination of some aldehydes, hydroxy aldehydes, unsaturated aldehydes, hydroxy carboxylic acids, carboxylic acids, alcohols
and polyols using an ultraviolet and a refractive index detector in series. The sample matrices are synthesis mixtures of
hydroxy carboxylic acids. The structures of the hydroxy aldehyde intermediates are determined by13C NMR and the influence of sample preparation on analysis results is discussed. The limits of detection and the precision
of the method are evaluated. 相似文献
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《Analytical letters》2012,45(6):1031-1042
The major compound in Cordyceps militaris (C. militaris), cordycepin, has been known to have a variety of pharmacological properties. The cordycepin concentration in artificially cultivated fruiting bodies of C. militaris was determined using quantitative 1H nuclear magnetic resonance spectroscopy (NMR). The results were compared with a high performance liquid chromatography (HPLC) method. There were no statistically significant differences in the cordycepin concentration by the two methods. Validation of each method was performed in terms of linearity, limit of detection, limit of quantification, intra- and inter-day precision, repeatability, stability, and accuracy. Better inter-day precision, repeatability, stability, and accuracy were obtained by NMR than by HPLC. These results show that NMR is an alternative to HPLC for the determination of cordycepin in C. militaris fruiting bodies. 相似文献
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This paper reports a quantitative determination method of (−)-epicatechin in apple juices by measuring of its signal at 7.05 ppm in the 1H NMR spectrum. It is a direct method that does not need any previous derivatization. 1,3,5-Benzenetricarboxylic acid was added to the juice as internal standard for the determination of the absolute concentration of (−)-epicatechin. Ascorbic acid was also added to avoid enzymatic oxidation of the phenolics and to adjust the pH at 2.74, since the chemical shift of some compounds varies with the pH. Standard addition method accomplished with the juices of two different varieties of apples gave recoveries between 95 and 109%. The precision of the method was tested for repeatability (n=5) and reproducibility (n=13) obtaining a coefficient of variation of 5.8 and 8.6%, respectively. Limit of detection, calculated from “3Sy/x+intercept”, is 24 mg l−1. 相似文献
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研究了采用低场脉冲核磁共振(NMR)测定二醋酸纤维素丝束油剂的新方法,给出NMR法测定二醋酸纤维素丝束油荆含量的标准曲线。同时对NMR法测量二醋酸纤维素丝束油荆不确定度进行了评估。结果表明,NMR法具有分析速度快、无污染、无损伤和准确度高的优点,适合于二醋酸纤维素丝束油荆的分析。 相似文献