Phase sensitive HMQC(Heteronuclear Multiple Quantum Coherence) and HSQC(Heteronuclear Single Quantum Coherence) experiments with t 1 noise reduction are proposed for the accurate measurement of heteronuclear one bond ...Phase sensitive HMQC(Heteronuclear Multiple Quantum Coherence) and HSQC(Heteronuclear Single Quantum Coherence) experiments with t 1 noise reduction are proposed for the accurate measurement of heteronuclear one bond 13 C 1H coupling constants. The resulting 2D spectra give anti phase splittings of heteronuclear one bond couplings along ω 2 dimension, so that the precision of coupling constant measurement is less subject to the residual t 1 noise. By combining use of data fitting procedure on a spectrum with enough digital resolution and signal to noise ratio, a precision of about 0 03 Hz can be achieved in the measurement of heteronuclear one bond coupling constants. The proposed method can be very useful for the study of residual dipolar couplings caused by the alignment in high magnetic field and the dynamic frequency shift caused by the cross correlation between chemical shift and spin dipolar interactions.展开更多
本研究通过使用灵敏度增强的带梯度形状脉冲进行异核单量子相干(HSQC)实验检测保健食品中违法添加的西地那非类物质。待测样品以甲醇溶解超声辅助提取,减压浓缩后以氘代DMSO溶解上机测试;利用Assure-NMR软件将得到的未知样品异核单量子...本研究通过使用灵敏度增强的带梯度形状脉冲进行异核单量子相干(HSQC)实验检测保健食品中违法添加的西地那非类物质。待测样品以甲醇溶解超声辅助提取,减压浓缩后以氘代DMSO溶解上机测试;利用Assure-NMR软件将得到的未知样品异核单量子相干(Heteronculear Single Quantum Coherence)谱图与已知西地那非类物质谱图进行模拟匹配。本方法检出限可以达到200μg·kg-1,能快速有效的对保健食品中西地那非类物质的违法添加侦察识别。该方法简便快捷,可以为食品安全监管部门提供一种新颖便捷的那非类物质监管稽查参考办法。展开更多
文摘Phase sensitive HMQC(Heteronuclear Multiple Quantum Coherence) and HSQC(Heteronuclear Single Quantum Coherence) experiments with t 1 noise reduction are proposed for the accurate measurement of heteronuclear one bond 13 C 1H coupling constants. The resulting 2D spectra give anti phase splittings of heteronuclear one bond couplings along ω 2 dimension, so that the precision of coupling constant measurement is less subject to the residual t 1 noise. By combining use of data fitting procedure on a spectrum with enough digital resolution and signal to noise ratio, a precision of about 0 03 Hz can be achieved in the measurement of heteronuclear one bond coupling constants. The proposed method can be very useful for the study of residual dipolar couplings caused by the alignment in high magnetic field and the dynamic frequency shift caused by the cross correlation between chemical shift and spin dipolar interactions.
文摘本研究通过使用灵敏度增强的带梯度形状脉冲进行异核单量子相干(HSQC)实验检测保健食品中违法添加的西地那非类物质。待测样品以甲醇溶解超声辅助提取,减压浓缩后以氘代DMSO溶解上机测试;利用Assure-NMR软件将得到的未知样品异核单量子相干(Heteronculear Single Quantum Coherence)谱图与已知西地那非类物质谱图进行模拟匹配。本方法检出限可以达到200μg·kg-1,能快速有效的对保健食品中西地那非类物质的违法添加侦察识别。该方法简便快捷,可以为食品安全监管部门提供一种新颖便捷的那非类物质监管稽查参考办法。
