转帖 仪器的本底信号太高了

最新回复

• firefox (2007-8-06 00:31:22)

  可能是你的溶剂（甲醇和乙腈或者其他溶剂）带来的，下面是一些容易污染质谱的化合物，279就在其中：
  m/z Ion Compound
  42 (M+H)+ acetonitrile
  59 (M+NH4)+ acetonitrile
  64 (M+Na)+ acetonitrile
  65 (2M+H)+ methanol
  79 (M+H)+ DMSO
  83 (2M+H)+ acetonitrile
  85 (M+H)+ d6-DMSO
  101 (M+Na)+ DMSO
  102 (M+H)+ triethylamine (TEA)
  104/106 (M+Cu)+ acetonitrile
  105 (2M+Na)+ acetonitrile
  120 (M+Na+CH3CN)+ DMSO
  122 (M+H)+ Tris
  123 (M+H)+ dimethylaminopyridine (DMAP)
  130 (M+H)+ diisopropylethylamine (DIPEA)
  144 (M+H)+ tripropylamine (TPA)
  145/147 (2M+Cu)+ acetonitrile
  146 (3M+Na)+ acetonitrile
  150 (M+H)+ phenyldiethylamine
  153 (M+H)+ 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
  157 (2M+H)+ DMSO
  159 (M+Na)+ sodium trifluoroacetate
  169 (2M+H)+ d6-DMSO
  179 (2M+Na)+ DMSO
  186 (M+H)+ tributylamine
  214 (M+H)+ unidentified contaminant, maybe related to methanol
  225 (M+H)+ dicyclohexyl urea (DCU)
  239/241 [(M.HCl)2-Cl]+ triethylamine
  242 M+ tetrabutylammonium (C4H9)4N+
  243 M+ trityl cation
  257 (3M+H)+ DMSO
  273 M+ monomethoxytrityl cation (MMT)
  279 (M+H)+ dibutylphthalate (plasticiser)
  301 (M+Na)+ dibutylphthalate (plasticiser)
  317 (M+K)+ dibutylphthalate (plasticiser)
  338 (M+H)+ erucamide
  360 (M+Na)+ erucamide
  391 (M+H)+ diisooctyl phthalate (plasticiser)
  413 (M+Na)+ diisooctyl phthalate (plasticiser)
  425 (M+Na)+ unidentified contaminant (plasticiser)
  429 (M+K)+ diisooctyl phthalate (plasticiser)
  449 (2M+H)+ dicyclohexyl urea (DCU)
  454 (M+Na+CH3CN)+ diisooctyl phthalate (plasticiser)
  798 (2M+NH4)+ diisooctyl phthalate (plasticiser)
  803 (2M+Na)+ diisooctyl phthalate (plasticiser)
  

• mass (2007-8-06 00:31:30)

  多谢大侠指点！但如何能避免或者尽力避免这些污染？

• firefox (2007-8-06 00:32:00)

  1）更换不同厂家的溶剂，据说Merk的背景较小。
  2）选择合适的容器溶解样品，最好用玻璃试管。

• lwlwb (2007-8-07 15:52:26)

  如题。你作了那么多清洗应该把该洗的都洗了，该看看是不是流动相的问题了。其实仪器污染除非有非常大的误操作或长期的积累，否则不是那么容易出问题的。

• firefox (2007-8-08 00:21:01)

  这几个离子：149、279，邻苯二甲酸甲酯（增塑剂）完全是用塑料的东西带来的。只要你尽量少用塑料的东西就好了：瓶子啦、eppendorf管、塑料管线等等。完全避免八成不可能，但是，说不定你最近用的某样东西，增塑剂很容易掉下来。