Overview of Analytical Techiques for Herbicides in Food

It is said that there are more than 5800 kinds of weeds, which significantly do harm to the agricultural production and weed control has always been an important issue in agrochemical practice. Chemical agents, that is herbicides, are used widely in the world in protecting crops from undue competition from weeds. The main chemical classes of herbicides(Tadeo et al., 2000) include bipiridilium compounds, triazine derivatives containing three heterocyclic nitrogen atoms in the ring structure (atrazine, prometryn, propazin, etc.), chlorophenoxy acid derivatives (2, 4-D, 2, 4, 5-T), substituted chloro-acetanilides (alachlor, propachlor), derivatives of 2, 6-dinitroaniline (benfluralin, trifluralin), substituted phenylcarbamates (carbetamide, chlorbufam), urea derivatives (chlorbromuron, chlorotoluron), substituted sulphonylureas (amidosulfuron, trifusulfuron), etc. The intensive application of herbicides has resulted in the contamination of the atmosphere, soil and waste water, agricultural products (wheat, corn, fruits, vegetables, beans etc.) and, consequently, in the direct or indirect pollution of food and food products and biological system. More studies have shown that herbicides or its metabolites can enter into the human body along food chain, which creates potential health risks to human. Growing concern has been taken for this issue and some herbicides have been banned to use (see table 1). The development of a robust analytical method is a complex issue. All steps in the analytical process including sample preparation, extraction, cleanup and instrumental analysis are equally important. There are a vast series of techiniques to use in establishing analytical methods, however, some rules should be taken for the differences in polarity of herbicides and the type of sample matrix. The objective of this paper is to summarize the anlytical measures developed to detect the different classes of herbicides residues in various foods, and to review future trends.