State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan 430071, China.
J Magn Reson. 2010 Sep;206(1):157-60. doi: 10.1016/j.jmr.2010.06.003. Epub 2010 Jun 9.
Choline nitrogen ((14)N) has a long relaxation time (seconds) which is due to the highly symmetric chemical environments. (14)N in choline also has coupling constants with protons (0.6 Hz to methyl protons, 2.7 Hz to CH(2)O protons and 0.2 Hz to NCH(2) protons). Based on these properties, we introduce a two-dimensional NMR method to detect choline and its derivatives in solutions. This method is the (1)H-(14)N hetero-nuclear single-quantum correlation (HSQC) experiment which has been developed in solid-state NMR in recent years. Experiments have demonstrated that the (1)H-(14)N HSQC technique is a sensitive method for detection of choline-containing compounds in solutions. From 1mM choline solution in 16 min on a 500 MHz NMR spectrometer, a (1)H-(14)N HSQC spectrum has been recorded with a signal-to-noise ratio of 1700. Free choline, phosphocholine and glycerophosphocholine in milk can be well separated in (1)H-(14)N HSQC spectra. This technique would become a promising analytical approach to mixture analyses where choline-containing compounds are of interest, such as tissue extracts, body fluids and food solutions.
胆碱氮（(14)N）具有较长的弛豫时间（秒），这是由于其高度对称的化学环境所致。（14）N 在胆碱中还与质子具有耦合常数（与甲基质子为 0.6 Hz，与 CH(2)O 质子为 2.7 Hz，与 NCH(2)质子为 0.2 Hz）。基于这些特性，我们引入了一种二维 NMR 方法来检测溶液中的胆碱及其衍生物。该方法是近年来在固态 NMR 中发展起来的 (1)H-(14)N 异核单量子相关（HSQC）实验。实验表明，(1)H-(14)N HSQC 技术是一种检测溶液中含胆碱化合物的灵敏方法。在 500 MHz NMR 光谱仪上，从 1mM 胆碱溶液中，在 16 分钟内记录了具有 1700 信噪比的 (1)H-(14)N HSQC 谱。牛奶中的游离胆碱、磷酸胆碱和甘油磷酸胆碱可以在 (1)H-(14)N HSQC 谱中很好地分离。该技术将成为一种有前途的分析方法，用于混合物分析，其中含胆碱化合物是感兴趣的，如组织提取物、体液和食物溶液。
