Solid-phase extraction immunosorbent

The low selectivity of the SPE columns currently in use can be increased with more selective sorbents such as the immunosorbents, which have been quite extensively used in SPE-LC (72). Immunoaffinity-based solid-phase extraction (lASPE) sorbents have also been used in coupled gas chromatography for determining... 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical methods. 

D.S. Aga, E.M. Thurman, and M.L. Pomes, Determination of alachlor and its sulfonic acid metabolite in water by solid-phase extraction and enzyme-linked immunosorbent assay. Anal. Chem. 66, 1495-1499 (1994). 

ECD = electron capture detector ELISA = enzyme-linked immunosorbent assay GC = gas chromatography HRGC = high resolution gaschromatography MS = mass spectrometry MTBE = methyl-tert-butyl ether ppb = parts per billion ppm = parts per million ppt = parts per trillion SPE = solid phase extraction... 

In the past two decades quite a few new techniques have emerged for the treatment of aqueous samples prior to organic analysis. Perhaps the most important development is that of solid-phase extraction (SPE), which has successfully replaced many off-line steps. This technique can be considered to have introduced a genuine new era in sample handling [1]. The many varieties in which the technique is available and can be applied have made it the key step in handling of aqueous samples. Among the successful varieties are solid-phase microextraction (SPME), matrix solid-phase dispersion, disk extraction and immunosorbent extraction. Several reviews covering these topics have appeared in the literature in the past decade (see e.g. Refs. [2,3] for nonylphenol... 

T. K. Nevanen, H. Simolin, T. Suortti, A. Koivula, and H. Soderlund, Development of a High-Throughput Format for Solid-Phase Extraction of Enantiomers Using an Immunosorbent in 384-Well Plates, Anal. Chem. 2005, 77, 3038. 

Li, Z., S. Wang, N. Alice Lee, et al. 2004. Development of a solid-phase extraction-enzyme-linked immunosorbent assay method for the determination of estrone in water. Anal. Chim. Acta 503 171-177. 

Nichkova, M. and M.R Marco. 2005. Development and evaluation of C18 and immunosorbent solid-phase extraction methods prior to immunochemical analysis of chlorophenols in human urine. Anal. Chim. Acta 533 67-82. 

Immunoaffinity sorbents (ISs) are more selective compared to ODS sorbents. The first commercial ISs were introduced for the cleanup of samples for the determination of aflatox-ins (Groopman and Donahue, 1988). ISs have been synthesized for a limited number of pesticides and pesticide classes. Immunosorbents arc formed by covalently bonding antibodies to an appropriate sorbent. Immunosorbent is packed into a solid phase extraction cartridge or precolumn as a classical extraction sorbent (Bouzige and Pichon, 1998). There is much interest in developing ISs for single analytes, which are particularly difficult to analyze at the trace level because of a lack of available extraction methods,. such as acephate and methamidophs. 

In the field of solid-phase extraction (SPE) methods, research is oriented toward the identification and synthesis of new sorbents with increased selectivity. It has already been shown that polar adsorbents such as Oasis HLB (vinylpyrrolidone-divinylbenzene copolymer) can isolate organophosphorous pesticides from blood or serum, or triazines, acetamides and phenoxy acids from surface and waste water. Recently, a new polymeric material, polyaniline, was introduced for the extraction of chlorophenolic pesticides in water samples. Immunosorbents produced by covalent immobilization of the antibody generated against the target analyte on... 

Enzyme-linked immunosorbent assay is a heterogenous immunoassay. Reactions involve a solid phase to which components are sequentially presented and successively bound. This method is very effective in the determination of the total alkaloid content. The positive characteristics of this method are the use of non-toxic reagents and basic equipment with low costs, a small sample volume and the ability to measure alkaloids in crude sample extracts. According to the literature, compared with results obtained from GLC, the precision of ELISA for quinolizidine alkaloids is not as high as that of the gas chromatography procedure, but is adequate for plant breeding purposes. The use of enzymes in developing the methods of quinolizidine alkaloids analysis looks likely to increase in the future. 

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