找回密码
 马上注册

扫一扫,访问微社区

搜索
热搜: mestrenova
查看: 3526|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 8 s% M1 f- W, A$ ?! S0 M0 s) Sof a sample, especially one which requires signal averaging or phase* [- e; P4 [: t8 l- s4 P; ? cycling, you need to have a temporally constant and spatially # ]. E: L/ k1 `! {+ D3 t. ihomogeneous magnetic field. Consistency of the Bo" b% o% c. p% J$ \ field over time will be discussed here; homogeneity will be discussed }" C; u, t; o3 x0 E! n- ^in the next section of this chapter. The field strength might vary over' X- i/ Q5 x8 m time due to aging of the magnet, movement of metal objects near the 5 e+ o8 ^+ |6 e c8 imagnet, and temperature fluctuations. Here is an example of a one line + G$ `" P: [ s# }3 YNMR spectrum of cyclohexane recorded while the Bo magnetic field was drifting a very significant amount.  8 f" W3 `6 Z. M7 s/ @5 M$ K* n! dThe field lock can compensate for these variations.

4 z/ e6 w; X$ Q The field lock is a separate NMR spectrometer within your spectrometer. 3 E9 | W/ k) E E4 b0 C* b QThis spectrometer is typically tuned to the deuterium NMR resonance $ r1 Y* R$ A `6 ^" y- Ofrequency. It constantly monitors the resonance frequency of the # L5 R" ?, p: o; n- b& tdeuterium signal and makes minor changes in the Bo magnetic field to keep the 2 t' ]- p) d5 v& [( @resonance frequency constant. The deuterium signal comes from the0 \0 D v: f G U4 v deuterium solvent used to prepare the sample. The animation window  ' t c3 r" t6 O' zcontains plots of the deuterium resonance lock frequency, the small5 W6 i W8 {( |2 o @- I% u additional magnetic field used to correct the lock frequency, and the ; g# M: p: D8 Q$ h9 O; g. w$ wresultant Bo" @/ T \0 A& ]6 r2 y field as a function of time while the magnetic field is drifting. The $ q$ o( a( T8 n: Mlock frequency plot displays the frequency without correction. In! w) e/ o# D4 \/ s y reality, this frequency would be kept constant by the application of 0 Q( e7 k# J% o _8 l7 N. ]3 o, athe lock field which offsets the drift.


9 O9 b7 e4 j; r* T. k% w) V2 f$ X$ B4 D( Y 7 W/ ~* r( o: g9 S8 r On most NMR spectrometers the deuterium lock serves a second function. It provides the =0 $ z6 `8 z( s3 W% ]0 `) U2 preference. The resonance frequency of the deuterium signal in many lock5 v: Y3 G* U" C5 }1 Q$ y solvents is well known. Therefore the difference in resonance frequency $ U- r; N' `+ a; b7 I4 c" D# rof the lock solvent and TMS is also known. As a consequence, TMS does % _ P7 n, g, D/ f, W* vnot need to be added to the sample to set =0; the spectrometer can use the lock frequency to calculate # `% [/ ~- w4 k: L1 ^; @$ e* J=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?
3 `/ F4 d+ A& w6 i: E

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

' {+ I! A1 s' `6 q# x/ u J4 s

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, 2025-11-22 04:18

Powered by Discuz! X3.5

© 2001-2024 Discuz! Team.

快速回复 返回顶部 返回列表