Immunosorbents

An enzyme-linked immunosorbent assay (eflsa) has been developed for the detection of residues on hands. As Httle as 50 pg of TNT can be detected (126). Liquid chromatography/thermospray negative-ion tandem ms has been successfully used to detect picogram levels of explosives in post-blast debris (127). 

MacroHdes are obtained by controUed submerged aerobic fermentations of soil microorganisms. Although species of Streptomjces have dominated, species of Saccharopoljspora Micromonospora and Streptoverticillium are also weU represented. New techniques such as enzyme-linked immunosorbent assay (ELISA) based assays may prove beneficial for discovering new stmctures (464). 

V. Pichon, F. Chen and M.-C. Hennion, On-line preconcenti ation and liquid cliromato-graphic analysis of phenylurea pesticides in environmental water using a silica-based immunosorbent , Aim/. Chim. Acta 311 429-436 (1995). 

I. Fener, V. Pichon, M-C. Hennion and D. Barcelo, Automated sample preparation with exti action columns by means of anti-isoproturon immunosorbents foi the determination of phenylurea herbicides in water followed by liquid chi omatography-diode aixay detection and liquid cliromatogi aphy-atmospheric pressure chemical ionization mass spectrometiy , 7. Chromatogr. 777 91-98 (1997). 

The sorbents that are most frequently used in environmental analysis are Cig-silica based sorbents, polymeric sorbents (usually styrenedivinilbenzene) and graphitized carbon. In order to increase the selectivity of these sorbents, immunosorbents (35, 36) have been developed and used with good results, while recently, molecularly imprinted polymers have started be to used (35, 36). 

One problem with SPE-LC is the low selectivity of the precolumn. Immunosorbents, which have been developed for a few compounds (72), can considerably improve selectivity. The selectivity was high for different pollutants (73, 74). Figure 13.14 shows that selectivity is higher with an anti-isoproturon cartridge than with aPLRP-S precolumn. 

These small columns,(usually 10 mm X 1-4.6 mm i.d.) are normally packed with 10-40 p.m sorbents such as Cig-bonded silica, Cg-bonded silica or styrene-divinylbenzene copolymer. These sorbents are not very selective and more selective sorbents, such as the immunosorbent (94), have also been used with good results. Coupling of SPE-gas chromatography is in fact the one most often used in environmental analysis because it reaches a high level of trace enrichment, eliminates water and elutes retained compounds easily with an organic solvent that can be injected into the gas chromatograph. 

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... 

V. Pichon, M. Bouzige, C. Miege and M. C. Hennion, Immunosorbents natural molecular recognition materials for sample preparation of complex environmental matrices . Trends. Anal. Chem. 18 219-235 (1999). 

I. Eeirer, M. C. Hennion and D. Barcelo, Immunosorbents coupled on-line with liquid chi omatography/atmospheric pressure chemical ionization/mass specti ometiy for the part per trillion level determination of pesticides in sediments and natural waters using low preconcenti ation volumes . Anal. Chem. 69 4508-4514 (1997). 

The important advantage of the immunosorbents based on WPG-PA is the fast rate of biospecific interaction between the oligosaccharides and antibodies. For B-trisaccharide-WPG-PA the average sorption time of monoclonal B8 antibodies was 20 times shorter than with B-trisaccharide-Sepharose 4B. The role of the flexible polymeric spacer, therefore, is in this case very pronounced. 

In each of the assays of potency the amount of the immunoglobulin and the amount of a corresponding standard preparation that are required to neutralize the infectivity or other biological activity of a defined amount of virus or to neutralize a defined amount of a bacterial toxin are determined. The two determined amounts and the assigned unitage of the standard preparation are then used to calculate the potency of the immunoglobulin in International Units (lU). ELISA, enzyme-linked immunosorbent assay. 

HPLC, high-petfomtance liquid chromatogtaphy ELISA, enzyme-linked immunosorbent assay method RIA, radioimmunoassay method. 

Several heterogeneous electrochemical enzyme immunoassays have been demonstrated. These are based on the enzyme-linked immunosorbent assay (ELISA) technique... 

ELISA Enzyme-linked immunosorbent assay EMS Eosinophilia-myalgia syndrome ENS Enteric nervous system EO Eosinophil... 

Morishita, N., Kamiya, K., Matsumoto, T., Sakai, S., Teshima, R., Urisu, A., Moriyama, T., Ogawa, T., Akiyama, H., and Morimatsu, F. (2008). A reliable enzyme-linked immunosorbent assay for determination of soybean proteins in processed foods. /. Agric. Food Chem. 56, 6818-6824. 

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