LC-MS/MS signal suppression effects in the analysis of pesticides in complex environmental matrices

The application of LC separation and mobile phase additives in addressing L C-MS/MS matrix signal suppression effects for the analysis of pesticides in a complex environmental matrix was investigated. It was shown that signal suppression is most significant for analytes eluting early in the LC-MS ana lysis. Introduction of different buffers (e.g. ammonium formate, ammonium h ydroxide, formic acid) into the LC mobile phase was effective in improving signal correlation between the matrix and standard samples. The signal impr ovement is dependent on buffer concentration as well as LC separation of th e matrix components. The application of LC separation alone was not effecti ve in addressing suppression effects when characterizing complex matrix sam ples. Overloading of the LC column by matrix components was found to signif icantly contribute to analyte-matrix co-elution and suppression of signal. This signal suppression effect can be efficiently compensated by 2D LC (LC- LC) separation techniques. The effectiveness of buffers and LC separation i n improving signal correlation between standard and matrix samples is discu ssed.