Analytical Sciences

Chemiluminescent ELISA for the BTEX Determination in Water and Soil

Elisabetta MAIOLINI,* Dietmar KNOPP,** Reinhard NIESSNER,** Sergei EREMIN,*** Luca BOLELLI,* Elida Nora FERRI,* and Stefano GIROTTI*

*Dipartimento di Scienza dei Metalli, Elettrochimica e Tecniche Chimiche, Università di Bologna, Via S. Donato 15, 40127 Bologna, Italy
**Institute of Hydrochemistry and Chemical Balneology, Technische Universität München, 81377 München, Germany
***Department of Chemical Enzymology, Faculty of Chemistry, M. V. Lomonosov Moscow State University, Moscow 119899, Russia

An indirect competitive chemiluminescence enzyme-linked immunosorbent assay (CL-ELISA) for the determination of benzene, toluene, ethylbenzene, and ortho-, meta-, para-xylenes (BTEX) in soil and water was developed. The assay was optimized concerning the coating conjugate concentration, anti-BTEX antiserum dilution, incubation time effect on primary and secondary antibody incubation, and temperature effect on the competitive step and tolerance to different organic solvents. The IC₅₀ and lower limit of the detection (LDD₉₀) values were 4.6 and 0.5 μg mL⁻¹, respectively. While water samples could be analyzed directly, soil has to be extracted and diluted prior to immunochemical measurements. BTEX could be recovered from spiked soil with a yield higher than 60% using 5-min ultrasonication with methanol. Finally, the assay was applied to soil and water samples collected at a contaminated site in Italy, and was compared to GC-MS.

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