Immunoextraction of pesticides at the trace level in environmental matrices

Abstract

T he determ i n ation of organic pollutants in complex environmental matrices such as surface waters, sediments, soils, plant tissues or foodstuffs at a trace-level is laborious, time-consuming and often not reliable because sample pretreatment procedures involve too many steps and also because current solid-phase extraction sorbents are non selective. Many matrix components are co-extracted and coe l u t e d, so that an additional clean-up is usually re q u i re d prior to the final analysis by gas (GC) or liquid chromatography (LC). The selectivity can be greatly improved by providing new ex t raction sorbents involving antige n -a n t i b o dy interactions, so called immunosorbents (ISs). Antibodies are covalently bonded onto an appropriate sorbent to form the IS, to be packed into a solid-phase extraction cartridge or a precolumn and used as a classical extraction sorbent.Immunochemistry has been introduced for a long time for analysis and/or sample pretreatment in the medical and biological field, but, its introduction in the environmental field is re l at ive ly re c e n t , c e rt a i n ly because of the difficulty of making antibodies for small molecules. In the medical field, ISs have been often developed for the analysis of a single analyte and its metabolites which are structurally related to the parent molecule.In contrast to immunoassays, ISs provide individual quant i fi c ation of each analy t e s , b e c a u s e, once the compounds have been recognized and extracted onto the IS, they are desorbed, separated and analyzed. Therefore the cross-reactivity which can be a problem for immunoassays can be used in this case for the selective extraction of a whole group of structurally related compounds.The first commercial ISs were introduced for the cleanup of samples for the determination of aflatoxins. Other ISs have been described in the literature for the analysis of single pesticides such as carbendazim, chlortoluron, atrazine or t e r butylazine [1][2][3][4]. Howeve r, because of the unavo i d abl e cross-reactivity of antibodies tailored for small molecules, ISs we re also developed for the selective ex t raction of a whole group of structurally related compounds such as the triazine and phenylurea pesticides including their metabolites [5][6][7][8][9][10][11]. The class-selective trapping is now recognized as a key fe at u re of ISs to be tailored for env i ro n m e n t a l analysis of pesticides. There is also an interest to develop IS for single analytes which are particularly difficult to analyze at tra c e -l evel because of the lack of ava i l able ex t ra c t i o n methods from water such as aminotriazole. Synthesis of the immunosorbentsThe overall process for the preparation of an immunosorbent first involves the production of antibodies. Low molecular mass compounds such as pesticides are unable to evoke an i m mune re s p o n s e. Then production of antibodies towa rd s small molecules (haptens) invo l ves the at t a chment of this molecule (or an analog of it) to a larger molecule, as a...

Liquid Chromatographic and validation study in separation and determination of benzidines and phenols in the main discharge point of wastewater

“…The content of benzidinic compounds in aqueous samples can be determined by various analytical instrumental methods, such as a gas chromatography(GC)/mass spectrometric assay [8], rapid colourimetry [9], fluorescence spectrographic method [10] [10],novel resonance light scattering (RLS) [11], ion selective electrodes [12] , direct injection and Ultrahigh-pressure liquid chromatography (UPLC) with fluorescence detection [13], and high-performance liquid chromatography with various detectors such as UV detector [14] , mass spectroscopy detector [15] electrochemical detector [16].…”