主题：【已应助】【求助】请问质谱单品优化问题

楼主要测定这个农药，那么肯定是要优化方法，但是个人认为对于母离子没必要进行自动优化，待确定母离子和子离子后再进行自动优化即可。

原文由 malimali2006(malimali2006) 发表:
3200 Q trap做100种农药分析
在优化质谱参数的时候，每个农药逐个进行优化，目前已经优化好90多种，还有4个农药母离子含量太低无法自动完成优化，进样浓度已经是10个ppm了，目前我用手动优化，Q1扫描手动优化DP,EP使得母离子浓度达到8e4左右了，然后自动优化，结果说浓度太低无法完成优化，那么请问我是否要继续进行手动优化MS2扫描，然后进行MRM手动优化？请问如何操作？这四个农药是Pyriftalid,cycloprothrin,Milbemctin A3, Milbemctin A4

若要同时定量这么多化合物，那么方法上要更大程度的照顾响应低的化合物。

像这样的响应，估计检测限不会做得太低。实在要优化的话可以再提高些浓度吧。不过有些农药在液质上响应确实比较低。这几个农药没做过。


我有个资料上有Pyriftalid（环酯草醚319.1->139.1/179.1,这个是不是在液相上保留或者在质谱上响应不太好，我有这个农药的优化参数，但在经液相分析时，没有这个物质的RT和强度）。


cycloprothrin（乙氰菊酯，参考一下这个帖子http://www.instrument.com.cn/bbs/shtml/20090831/2088649/）。


后两个貌似笔误，是Milbemectin A4（密灭汀A4）、Milbemectin A3（密灭汀A3）。有以下一篇文献，主要用的是荧光，涉及到液质的辅助定性，提到Milbemectin。楼主可以查一下原文。


J Chromatogr A. 2000 Oct 27;896(1-2):75-85.

Liquid chromatographic determination of emamectin, milbemectin, ivermectin and abamectin in crops and confirmation by liquid chromatography-mass spectrometry.
Yoshii K, Kaihara A, Tsumura Y, Ishimitsu S, Tonogai Y.

Ministry of Health and Welfare, National Institute of Health Sciences, Osaka Branch, Japan.

Emamectin, milbemectin, ivermectin and abamectin are similar macrocyclic lactone chemicals used as an acaricides or parasiticides. We developed a simultaneous analytical method for determining the residual amounts of these compounds and emamectin metabolites in crops. A sample extracted with acetone was cleaned up with Bond Elut C18 and NH2. The sample was then fluorescence-derivatized with trifluoroacetic anhydride and 1-methylimidazole in acetonitrile. The analyte was measured by HPLC with fluorescence detection using an octadecylsilyl column with 3 microm particle size and gradient elution. In most crops, their recoveries by the developed method were ca. 80-110%. The detection limits of the analytes in vegetables were 0.1-0.3 ppt. Using the developed method, we surveyed the residues of these compounds in 20 commercial crops in Osaka, Japan. The result of the surveillance was that emamectin benzoate of 0.2-6.7 ppb was detected in nine cases and milbemectin of 16.7-279.3 ppb was detected in four cases. The detected samples were confirmed by LC-electrospray ionization (ESI) MS. The limit of detection by LC-ESI-MS was similar to the fluorescence detection level of 0.1-0.3 ppt in vegetables except for milbemectin.

分感谢大家的热情帮助，小猪飞飞提供的资料非常有用，再次谢过，请问cycloprothrin这个农药如果用lc/ms/ms做呢，我以499。1为母离子，发现好像不行啊。另外如果用手动优化的话具体怎操作，我的是ABI3200质朴，感激不尽。

限定 好母离子和子离后 优化出来的条件，丰度比较低。我做孕激素用负模式，就是优化不出来。