主题：【求助】求教气质高手

有点不明白的是你是用的吸附小分子非极性的萃取头，怎么可能会出来小分子的酸，和醛呢？这些物质的极性都是比较大。
匹配度不高，个人觉得有一个原因是峰的纯度不够，可以改变下程序看看能不能分的干净一点。

原文由 hiablen 发表:
有点不明白的是你是用的吸附小分子非极性的萃取头，怎么可能会出来小分子的酸，和醛呢？这些物质的极性都是比较大。
匹配度不高，个人觉得有一个原因是峰的纯度不够，可以改变下程序看看能不能分的干净一点。

初学气质,很多不懂，用这个萃取头也是参考的文献，他那上面出来的物质蛮好的，有酸又有醛类，还有萃取头是非极性的，那用极性的毛细管柱合适吗？一般匹配率多大以上才算比较合适啊

原文由 jetowl 发表:
初学气质,很多不懂，用这个萃取头也是参考的文献，

Polydimethylsiloxane (PDMS) fibers,( non-polar) should be OK for the flavor components.

他那上面出来的物质蛮好的，有酸又有醛类，还有萃取头是非极性的

What is the thickness of matrix active group (polydimethylsiloxane coating)? Are you using 100μm coating? that 100 μm coating thickness is recommended for low molecular weight or non-polar high molecular weight compounds. Or equivalent with the one in the参考的文献?

If want to obtain a decent result, need to pay attention to the optimization of the SPME method withg PDMS: Carry-over effect / Position of the fiber in the gc injector/ Extraction conditions, such as the duration of absorption and desorption, temperature of extraction, and the polarity and structure of the fiber.
(here is the basic SPE info:
http://www.sigmaaldrich.com/Brands/Supelco_Home/Spotlights/SPME_central.html
) If use the 30 μm or a 7 μm PDMS fiber, could extract the non-polar semivolatiles or large molecular weight compounds more effectively.

So try to do more research on that 参考的文献: find out the right PDMS fiber they used. (100 μm coating or 30 μm or a 7 μm).

Enclosed two Lits from Varian Inc. Hope it help.

原文由 hiablen 发表:
个人觉得有一个原因是峰的纯度不够，可以改变下程序看看能不能分的干净一点。

I do agree with hiablen: need some optimization on that.
Flavor
flavor 2

ciaclin:

I really appreciate it!

But I still have some questions.

Firstly, you said "Polydimethylsiloxane (PDMS) fibers,( non-polar) should be OK for the flavor components.", so you mean it's feasible for this analysis?
Secondly, I'm using Supelco 57301 as the fiber,according to the instruction, it's 100um, recommended for low molecular weight nonpolar compounds, if I use this fiber,can I get the acid or alcohol absorbed?
Thirdly, some peak in this specture are sharp, it means the peak is single,doesn't it?  If the peak isn't single, it may has several compounds, because of this, will it make the m/z large, and the result of search comes out to be a high molecular weight compound?
I'm puzzled!!Please help!!
Lastly, can you speak Chinese, if you can, could you please revert in CHINESE!
THANK YOU!!

regards!

原文由 jetowl 发表:
you said "Polydimethylsiloxane (PDMS) fibers,( non-polar) should be OK for the flavor components.", so you mean it's feasible for this analysis?
Secondly, I'm using Supelco 57301 as the fiber,according to the instruction, it's 100um, recommended for low molecular weight nonpolar compounds, if I use this fiber,can I get the acid or alcohol absorbed?
-------------------
Sorry, Can’t not type Chinese in the office. ( asked IT guys to fix this problem, but they so lazy…American is so stupid/lazy.)
Maybe it works. Also it maybe work on the acids, alcohol, aldehydes (ketone), however, that is not a good one. But “the Supelco 57301  the fiber ( 100 um) PDMS”has  better SPE affinity to the high molecular weight non-polar compounds, that maybe the reason you got so many unknown peak ( high molecular compounds).
So if your analyte is low molecular polar acid, alcohol, aldehydes (ketone), recommend the SPME fiber assembly, carbpwax-polyethyele (PEG), Supelco#57355-U, it should be good to go for the polar low molecular compounds.
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Thirdly, some peak in this specture are sharp, it means the peak is single,doesn't it?  If the peak isn't single, it may has several compounds, ----------- --------- -----------------------
Yes, you are right
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because of this, will it make the m/z large, and the result of search comes out to be a high molecular weight compound?
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No, this did not contribute any larger m/z .the GC/MSD analysis the fragment ions based on the m/z, not the retention time. 匹配因子太小，不建议采纳。<P>以上文本借助<A href="http://www.inputking.com/"

你空白什么样的？匹配度低你把扫描范围扩大些可能会好点，你出现的物质我做过这种东西。