Gas Chromatography/Mass Spectrometry Methods in Pesticide Analysis

Abstract

Gas chromatography/mass spectrometry (GC/MS) is irreplaceable in pesticide analysis. Nowadays international bodies consider mass spectrometry (MS) the method of choice for pesticide analysis and quantitative methods using GC/MS are more and more numerous. 1,2 The key characteristics of GC/MS in pesticide analysis are its selectivity and sensitivity, but other important features will be considered in detail in the specific sections on identification and quantitative analysis. A great advantage of GC/MS in identification is that it gives a mass spectrum that can be easily and quickly compared on‐line with a library of more than 200 000 mass spectra. Specific pesticide libraries are available with hundreds of compounds. Mass spectra can be obtained with just a few picograms of compound injected and gas chromatography (GC) can separate analytes. This is an unbeatable feature of GC/MS. In quantitative analysis, sensitivity is often excellent and selectivity is better than with other GC detectors. Multiresidue analyses can easily be done. The use of internal standards labeled with stable isotopes allows an accuracy which is not achieved with common methods. These characteristics facilitate sample processing because cleanup stages are not necessary in many cases. Major limitations in the use of GC/MS depend on GC limits. Thus, very polar and thermally labile pesticides, not suitable for GC analysis, cannot be analyzed by GC/MS. Other limitations are the cost of the apparatus and the relative complexity of the method, compared with the simpler GC detectors. However, these limitations are gradually becoming less important as GC/MS instruments become simpler and cheaper.