ANALYTICA zyxwvut CHIMICA zyxwvutsrqpo ACM zyxwvutsrqponm ELSEVIER Analytica Chimica Acta 311(1995) 371-376 Determination of Procymidone in vegetables by a commercial competitive inhibition enzyme immunoassay Amadeo R. Fernandez-Alba a,* , Antonio Valverde a, Ana Agiiera b, Mariano Contreras b, Dolores Rodriguez ’ a Pesticide Residues Research Group, Facultad de Ciencias de Abner& 04071 Abner&z,Spain b Laboratorio de An&is Agricola de COEXPhWL (Cosecheros-Exportaa’ores de Hortalizas de Almeria), El Viso, 04070 Almeria, Spain ’ Centro National de Biotecnologia C.S.I.C., Campus UniversidadAut&oma, Cantoblanco, 28049 Madrid, Spain Received 20 September 1994, revised 8 February 1995; accepted 13 February 1995 Abstract An ELISA commercial kit was used to quantitate residues of Procymidone at very low levels (< 20 pg/kg) in pepper samples. Samples were extracted with ethyl acetate-sodium sulphate and an aliquot is evaporated to dryness and reconstituted in 10 ml of light petroleum. Sample clean up is accomplished by aspirating 2 ml of the light petroleum extract through a silica gel solid phase disposable cartridge. Following aspiration, the sample was eluted with 2 ml of ethyl ether-petroleum ether (1:l). The eluted fraction was evaporated and dissolved with sonication in 2 ml of water before immunoassay analysis. The limit of Procymidone detection was 0.6 pg/kg. The assay logarithmic response was linear from 5 to 80 pg/kg of Procymidone residue. Irma-assay percentage coefficients of variation (%C.V.) ranged from 3.5 to 18.0 and inter-assays %C.V.s varied from 8.0 to 16.0. Comparison studies between gas chromatography with electron capture detection and ELBA analyses showed an acceptable coincidence at levels of 8 pg/kg. However, lower levels of ca. 2 pg/kg were detectable by ELISA only. No cross-reactivity problems were found in the ELBA test associated with the presence of other dichloroaniline derivatives and other pesticides studied. Keywords: Immunoassay; Enzymatic methods; Biosensors; Procymidone; Pesticides; Environmental analysis; ELISA, Vegetables 1. Introduction Procymidone (N-(3,5-dichlorophenyl)-1,2-di- methylcyclopropane-1,2-dicarboximide) is a system- atic fungicide that is widespread used in mediter- ranean agricultural areas as a preharvest treatment on fruits and vegetables to prevent Botrytis [l]. This pesticide is of special concern due to its chlorinated character and its persistence in the environment [2-41. It is therefore an important objective in monitoring food analysis. Tolerances in different countries/commodities for residues of Procymidone in vegetables are very variable and range from around 2.0 mg/kg in the EEC [5] to “nil” tolerance in the USA [6] and Switzerland [7], which is understood to be less than the limit of detection (L.O.D.) of 0.02 mg/kg bl. Currently the * Corresponding author. in vegetables is 0003-2670/95/$09.50 8 1995 Elsevier Science B.V. All rights reserved SSDI 0003-2670(95)00121-2 presence of Procymidone residues detected by applying well-known