| 查看: 1342 | 回复: 3 | |||
急速-蜗牛铁虫 (小有名气)
|
[求助]
求助关于LC/APCI-MS 已有1人参与
|
|
1、请问在LC/APCI-MS中，中性分子在APCI离子源中是不是只被离子化，不发生裂解？离子被碎片化是在APCI中还是在质谱中被碎片化的（离子是在哪里被碎片化的？）？ 2、APCI（大气压化学电离源）的负离子模式的工作基理是什么？是怎么由中性分子转变为负离子的？ |
回复此楼» 猜你喜欢
青椒八年已不青，大家都被折磨成啥样了？
已经有5人回复
-
青年基金C终止
已经有3人回复
-
26申博求博导推荐-遥感图像处理方向
已经有4人回复
-
限项规定
已经有7人回复
-
救命帖
已经有8人回复
-
招博士
已经有4人回复
-
西南交通大学国家级人才团队2026年博士研究生招生（考核制）—机械、材料、力学方向
已经有3人回复
-
英文综述是否需要润色及查重
已经有5人回复
-
为什么nbs上溴 没有产物点出现呢
已经有9人回复
-
最失望的一年
已经有18人回复
» 本主题相关商家推荐: (我也要在这里推广)
thecoldest
金虫 (正式写手)
- 应助: 148 (高中生)
- 金币: 1772.7
- 散金: 30
- 红花: 33
- 帖子: 588
- 在线: 116.3小时
- 虫号: 1119567
- 注册: 2010-10-11
- 专业: 药物分析
|
https://en.wikipedia.org/wiki/At ... chemical_ionization Ionization[edit]The analyte in solution is directly introduced into a pneumatic nebulizer via a direct inlet probe or through a connection to a standard high-performance liquid chromatography (HPLC) with an eluent flow rate between 0.2 and 2 mL/min. Once in the nebulizer, the analyte in solution is converted into a thin fog through the use of a high-speed nitrogen beam, and the droplets are then displaced by the gas flow through a heated quartz tube called a desolvation/vaporization chamber. [4] The mobile phase and the sample in the gas flow are then vaporized by the heat transferred to the spray droplets in the desolvation chamber and leave the tube as a mixture of the compounds of interest and hot gas (120oC).[4] They are subsequently carried along a corona discharge electrode where ionization occurs. The ionization can either be carried out in positive or negative ionization mode. In the positive mode, the relative proton affinities of the reactant ions and the gaseous analyte molecules allow either proton transfer or adduction of reactant gas ions to produce the ions of the molecular species. [4] In the negative mode, however, the ions are produced by either proton abstraction or adduct formation. In most cases, the evaporated mobile phase acts as the ionization gas and reactant ions are formed because of the effect of the corona discharge on the nebulized solvent. Generally, the primary ions formed by the corona discharge are ions such as a positively charged nitrogen or oxygen radical which can then form secondary reactant gas ions though collision with vaporized solvent molecules.[5] In a major distinction from chemical ionization, the electrons needed for the primary ionization are not produced by a heated filament, as a heated filament cannot be used under atmospheric pressure conditions. Instead, the ionization must occur using either corona discharges or β- particle emitters, which are both electron sources capable of handling the presence of corrosive or oxidizing gases. |
2楼2015-12-28 13:03:44
thecoldest
金虫 (正式写手)
- 应助: 148 (高中生)
- 金币: 1772.7
- 散金: 30
- 红花: 33
- 帖子: 588
- 在线: 116.3小时
- 虫号: 1119567
- 注册: 2010-10-11
- 专业: 药物分析
急速-蜗牛3楼2015-12-28 13:24:06
急速-蜗牛
铁虫 (小有名气)
- 应助: 0 (幼儿园)
- 金币: 1428
- 散金: 30
- 帖子: 61
- 在线: 87.9小时
- 虫号: 3162406
- 注册: 2014-04-25
- 性别: GG
- 专业: 理论和计算化学
4楼2015-12-29 20:49:39