ABSTRACT
LC-MS/MS Analysis (Example 1) ....................................................................................... 148 7.4.1 MSPD Procedure ....................................................................................................... 148 7.4.2 Calibration ................................................................................................................. 149 7.4.3 LC-MS Analysis ....................................................................................................... 149 7.4.4 Optimization of MSPD Method ................................................................................ 149 7.4.5 Recovery Studies ....................................................................................................... 150 7.4.6 Validation of the Analytical Method ......................................................................... 152 7.4.7 Real Samples .............................................................................................................. 152
7.5 Multiresidue LC-MS/MS Determination of Nine Pesticides in Fruit Juices (Example 2) .... 153 7.5.1 LC-MS Analysis ....................................................................................................... 155 7.5.2 Sample Preparation .................................................................................................... 155 7.5.3 Optimization of LC-MS/MS Analysis ..................................................................... 156 7.5.4 Matrix-Matched Calibration and Matrix Effect ........................................................ 156 7.5.5 Validation of the Analytical Method ......................................................................... 158 7.5.6 Real Samples ............................................................................................................. 159
References ...................................................................................................................................... 159
Although gas chromatography (GC) has traditionally been applied for pesticide residue analysis, the use of liquid chromatography (LC) has grown rapidly in the last decade. Modern pesticides, together with their degradation products, can be considered as typical candidates for LC separation,
because of their medium to high polarity, and their thermolability and/or low volatility [1]. In general, optimization of LC separation is tedious and time-consuming, even with the support of the computer-assisted retention modeling [2,3]. Most LC-based methods use common ultraviolet (UV), uorescence, or electrochemical detection occasionally combined with postcolumn treatment, for example, derivatization. Mass spectrometry (MS) has the advantage over conventional detectors, because it can provide information for unambiguous analyte identi cation even with poor LC separation. Tandem mass spectrometry (MS/MS) uses two stages of mass analysis-one to preselect an ion and the second to analyze fragments induced by collision of an ion with an inert gas, such as argon or helium. LC coupled with MS/MS (LC-MS/MS) is capable of differentiation between analyte and matrix signal, as well as between the analytes that coelute, thus permitting quanti cation of pesticide traces in very complex matrices.
