dickwang2008
第2楼2009/12/13
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。
小猪飞飞
第3楼2009/12/13
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.