CHARACTERISTICS OF IMMUNOSORBENTS USED AS A NEW APPROACH TO SELECTIVESOLID-PHASE EXTRACTION IN ENVIRONMENTAL-ANALYSIS

The trace-level determination of organic pollutants in complex matrice s is difficult and often not reliable because the current extraction p rocedures are non-selective. New extraction sorbents involving antigen -antibody interactions, called immunosorbents (ISs), have been synthes ised in order to trap a group of structurally related pollutants. The IS capacity is always high for the analyte-antigen used to make the an tibodies, but can be low for some related compounds. In this work, we show the relationship that exists between capacity, breakthrough volum e and recovery of analytes because of the competition between the stru cturally related compounds for antibody sites. Breakthrough due to the overloading of the column should be avoided because calibration curve s are no longer linear. The capacity of two ISs, one made for trapping the triazine pesticide group and the second for the phenylurea group, have been optimised by selecting silica with 50 nm pore size. Calibra tion curves are linear for all the compounds in a mixture of ten pheny lureas up to a concentration of 5 to 10 mu g L-1 for each compound whe n handling 50 mL water samples through a precolumn packed with 0.22 g of IS. Under these conditions, reliable quantitative results are obtai ned because calibration curves are similar when compounds are alone or in a mixture. Application to the clean-up of soil extracts illustrate s the high selectivity and the high potential of these new sorbents in environmental analysis.