Chapter 30 - Modern Approaches to Analysis of Pesticide Residues in Foods and the Environment

Abstract

This chapter focuses on analytical techniques used for developing methodologies for analysis of pesticide residues in food and the environment. It briefly reviews the criteria that are used by enforcement agencies to evaluate method performance. A method is considered acceptable upon validation. This process may entail the examination of various parameters but always includes the establishment of a limit of quantitation (LOQ) and a limit of detection (LOD). The former is usually set at the lowest matrix fortification level, for which acceptable, quantifiable recoveries of the analyte(s) are obtained. Regulatory enforcement methods routinely deal with multiresidue determinations under fairly standardized conditions. Generally, extraction methodology must be developed such that nearly quantitative recovery of target analytes is obtained. At this stage of method development, techniques such as solvent extraction, supercritical fluid extraction (SFE), and pressurized liquid extraction are used. Traditional approaches to extract cleanup usually involve liquid/liquid partition. The most common technique focuses on differences in solubility (and polarity) of the matrix constituents. Gel permeation chromatography (GPC) is an established cleanup technique that separates (size exclusion) high-molecular-weight compounds such as proteins, fats, and sugars from relatively low molecular weight compounds such as pesticides in animal and plant matrices. A more efficient (but time-consuming) method involves liquid/solid partition. Techniques like Gas Chromatography-Mass Spectrometry (GS-MS) and Liquid chromatography (LC)-Mass Spectrometry (LS-MS) are used. The use of immunoassays (IAs) as pesticide residue analytical methods represents a radical departure from the more conventional chromatographic approaches. Capillary electrophoresis (CE) is generally only considered when conventional chromatographic approaches such as capillary GC, high-performance liquid chromatography (HPLC), and LC-MS fail to provide straightforward solutions, for the following reasons.