找回密码
 马上注册

扫一扫,访问微社区

搜索
热搜: mestrenova
查看: 3534|回复: 5

做C13NMR谱为什么要用氘代试剂?

[复制链接]
发表于 2009-8-18 08:48:16 | 显示全部楼层 |阅读模式
做C13NMR谱为什么要用氘代试剂?
回复

使用道具 举报

发表于 2009-8-18 12:13:31 | 显示全部楼层
 需要氘代溶剂来完成锁场(Field lock)和匀场(deuterium gradient shimming).

Field Lock

In order to produce a high resolution NMR spectrum& |- x! u) w$ R3 ~ of a sample, especially one which requires signal averaging or phase1 n R0 C/ I. l2 y! { cycling, you need to have a temporally constant and spatially " r: D5 w% f. j- Thomogeneous magnetic field. Consistency of the Bo1 }3 m8 P1 X7 G0 A) B& f/ O field over time will be discussed here; homogeneity will be discussed * h2 L4 {( E. zin the next section of this chapter. The field strength might vary over # R# d1 v8 n0 p7 h% G# y8 ~time due to aging of the magnet, movement of metal objects near the# a% Y9 }3 c+ [: c! J magnet, and temperature fluctuations. Here is an example of a one line # ~* t2 r6 M9 bNMR spectrum of cyclohexane recorded while the Bo magnetic field was drifting a very significant amount.  " [, j q9 H3 |0 S5 _/ v The field lock can compensate for these variations.

, N9 F6 K7 ^* `2 h; yThe field lock is a separate NMR spectrometer within your spectrometer./ z) H5 L* \* u/ v This spectrometer is typically tuned to the deuterium NMR resonance $ k e s% }( I% V: O' W zfrequency. It constantly monitors the resonance frequency of the5 S1 k7 D+ R0 g8 ] deuterium signal and makes minor changes in the Bo magnetic field to keep the/ B9 `) L# }6 N! p resonance frequency constant. The deuterium signal comes from the 2 ]3 H& L# F" A' Jdeuterium solvent used to prepare the sample. The animation window  ! j$ {1 Q, `3 W6 acontains plots of the deuterium resonance lock frequency, the small0 f" x1 w) a) S1 R- G+ r additional magnetic field used to correct the lock frequency, and the . d- B: j z' Iresultant Bo- k) [( i# P- ]0 t9 [* v- |, S5 K field as a function of time while the magnetic field is drifting. The 1 r: i" ^9 b, B9 S0 h/ h% elock frequency plot displays the frequency without correction. In+ W$ G$ X6 ?4 D& Y7 @. P$ b- N reality, this frequency would be kept constant by the application of 4 G8 W# ~9 M7 ~% Q5 Ithe lock field which offsets the drift.


6 j4 |" U4 i" h2 i2 q$ c/ h6 Q 5 {$ F* D/ `$ p1 ] b& o 0 j# k9 {/ _$ k; q$ @$ f0 U On most NMR spectrometers the deuterium lock serves a second function. It provides the =0 3 ^" B8 S1 I* I: U! Sreference. The resonance frequency of the deuterium signal in many lock i- n$ o) e/ I. wsolvents is well known. Therefore the difference in resonance frequency 1 L% V2 A6 v: x" u* ~- Cof the lock solvent and TMS is also known. As a consequence, TMS does : M4 f. N) m* X/ ~& b# qnot need to be added to the sample to set =0; the spectrometer can use the lock frequency to calculate % O8 F5 Z( {) Z& h4 u=0.




回复 支持 反对

使用道具 举报

 楼主| 发表于 2009-8-18 13:34:05 | 显示全部楼层
看不懂,有中文的没?
回复 支持 反对

使用道具 举报

发表于 2009-8-18 17:25:58 | 显示全部楼层
以下是引用cannotsay在2009-8-18 13:34:05的发言:
看不懂,有中文的没?
0 x9 N5 w/ I) ^3 H

现代NMR仪器要用氘锁

回复 支持 反对

使用道具 举报

发表于 2009-9-13 15:32:24 | 显示全部楼层

楼上说的还蛮有道理的哦

& ?5 p4 f$ F! J/ T# ?, Y: i7 [

超级师傅

回复 支持 反对

使用道具 举报

发表于 2009-9-16 15:59:52 | 显示全部楼层
 看看

回复 支持 反对

使用道具 举报

您需要登录后才可以回帖 登录 | 马上注册

本版积分规则

Archiver|手机版|中国核磁共振论坛

GMT+8, 2025-11-26 04:47

Powered by Discuz! X3.5

© 2001-2024 Discuz! Team.

快速回复 返回顶部 返回列表