Institute of Chemistry, University of Tartu, Ravila 14a, Tartu, 50411, Estonia.
Rapid Commun Mass Spectrom. 2011 Nov 15;25(21):3252-8. doi: 10.1002/rcm.5222.
Glyphosate is one of the most common pesticides used in the pre-harvest treatment of cereals. This paper examines the matrix effect of glyphosate liquid chromatography/electrospray ionization mass spectrometric (LC/ESI-MS) analysis in wheat and rye. The matrix effect (ionization suppression) was found to be dependent on sample particle size taken for the extraction. If samples are ground to very small particles severe ionization suppression occurs. For lower glyphosate contents (<1 mg/kg) the signal may even be suppressed by more than 90%. The matrix effect was found to be dependent on the matrix - rye showed significantly stronger ionization suppression than wheat, although these matrices are not very different. The matrix effect also depends on the concentration of glyphosate in the post-extraction spiked samples. It is demonstrated that the isotope-labelled standard (13)C(2)-glyphosate undergoes different ionization suppression than glyphosate and is therefore not efficient in compensating for matrix effect. At the same time the extrapolative dilution approach allows to efficiently compensate for matrix effect.
草甘膦是谷物收获前处理中最常用的农药之一。本文研究了草甘膦液相色谱/电喷雾电离质谱（LC/ESI-MS）分析在小麦和黑麦中的基质效应。发现基质效应（离子抑制）取决于提取时的样品粒径。如果将样品研磨成非常小的颗粒，则会发生严重的离子抑制。对于较低的草甘膦含量（<1mg/kg），信号甚至可能被抑制超过 90%。基质效应取决于基质——黑麦比小麦表现出更强的离子抑制，尽管这两种基质没有太大的区别。基质效应还取决于萃取后加标样品中草甘膦的浓度。实验证明，同位素标记标准品（13）C（2）-草甘膦的离子化抑制作用与草甘膦不同，因此不能有效地补偿基质效应。同时，外推稀释法可以有效地补偿基质效应。
