title: A cost-effective screening method for pesticide residue analysis in fruits, vegetables, and cereal grains.
abstract: This paper reports the results of studies performed to investigate the potential of applying thin layer chromatography (TLC) detection in combination with selected extraction and cleanup methods, for providing an alternative cost-effective analytical procedure for screening and confirmation of pesticide residues in plant commodities. The extraction was carried out with ethyl acetate and an on-line extraction method applying an acetone-dichloromethane mixture. The extracts were cleaned up with SX-3 gel, an adsorbent mixture of active carbon, magnesia, and diatomaceous earth, and on silica micro cartridges. The Rf values of 118 pesticides were tested in eleven elution systems with UV, and eight biotest methods and chemical detection reagents. Cabbage, green peas, orange, and tomatoes were selected as representative sample matrices for fruits and vegetables, while maize, rice, and wheat represented cereal grains. As an internal quality control measure, marker compounds were applied on each plate to verify the proper elution and detection conditions. The Rf values varied in the different elution systems. The best separation (widest Rf range) was achieved with silica gel (SG)--ethyl acetate (0.05-0.7), SG--benzene, (0.02-0.7) and reverse phase RP-18 F-254S layer with acetone: methanol: water/30:30:30 (v/v) (0.1-0.8). The relative standard deviation of Rf values (CV(Rf)) within laboratory reproducibility was generally less than 20%, except below 0.2 Rf, where the CVRf rapidly increased with decreasing Rf values. The fungi spore inhibition, chloroplast inhibition, and enzyme inhibition were found most suitable for detection of pesticides primarily for confirming their identity or screening for known substances. Their use for determination of pesticide residues in samples of unknown origin is not recommended.
authors.affiliation: International Atomic Energy Agency, FAO/IAEA Agriculture and Biotechnology Laboratory, Vienna, Austria. Ambrus.Arpad@ontsz.hu
authors.forename: A
authors.initials: A
authors.lastname: Ambrus
authors.forename: I
authors.initials: I
authors.lastname: Füzesi
authors.forename: M
authors.initials: M
authors.lastname: Susán
authors.forename: D
authors.initials: D
authors.lastname: Dobi
authors.forename: J
authors.initials: J
authors.lastname: Lantos
authors.forename: F
authors.initials: F
authors.lastname: Zakar
authors.forename: I
authors.initials: I
authors.lastname: Korsós
authors.forename: J
authors.initials: J
authors.lastname: Oláh
authors.forename: B B
authors.initials: BB
authors.lastname: Beke
authors.forename: L
authors.initials: L
authors.lastname: Katavics
mesh_terms: D002855:Chromatography, Thin Layer / Q000379:methods*; D003362:Cost-Benefit Analysis; D002523:Edible Grain; D005504:Food Analysis / Q000191:economics / Q000379:methods*; D005638:Fruit; D010573:Pesticide Residues / Q000032:analysis*; D014675:Vegetables
chemical_list: D010573:Pesticide Residues