Enzymatic reduction of phenthoate residues on eggplant (Solanum melongena esculentum) and tomato [Lycopersicum lycopersicon (L.) Karsten]

Date

10-2004

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Josefina L. Solivas

Abstract

The reduction of phenthoate. s-u-ethoxycarbonyl 0.0.thmethyl phowhomdithioale (Ci21-11704PS,) on laboratory and field-treated eggplant and tomato, using an organophosphate hydrolyzing enzyme. opdA. was studied. The enzyme. opdA. was isolated from a bacterial strait: Agrobacierium radiohaaerP230 and sequenced by Commonwealth Scientific and Industrial Research Organization (CSIRO) of Australia. Three different methodologies to determine the extraction efficiency of phenthoate were investigated. Extraction with petroleum ether and methylene chloride followed by florisil clean-up using 15% anhydrous ether/petroleum ether eltiant resulted to the highest recovery of 95.83% for tomato. The same methodology was used for eggplant and a recovery of 106.8% was obtained. The optimum enzyme dipping time was investigated using laboratory-treated eggplant and tomato. It was found that the optimum dipping time for eggplant was 15 minutes. with corresponding phenthoate residue reduction of 65.73%. The optimum dipping time fur tomato was 5 minutes with corresponding residue reduction of 43.74%. The effect of washing with running water and dipping in 0.05M tris buffer were also investigated. There was no significant reduction of phenthoate residues on eggplant and tomato resulting from washing samples with nursing ware, 10.1% and 16.4% respectively. Dipping eggplant and tomato samples in butter resulted to 19.8% and 14.3% phenthoate residue reduction respectively. and was considered insignificant compared to residue reduction by the enzyme. *File reduction of phenthoate on field-treated eggplant and tomato was further studied. Results showed that phenthoate residues were reduced by 28.86% - 40.43% on field-treated eggplant and 15.34 -34.04% on field-treated tomato. The persistence of phenthoate on eggplant and tomato was also studied based on their calculated half-lives. Calculated half-life of eggplant was 0.80 days and 0.87 days (0-2 Days After Spray (DAS)) and 3.02 days (1-7 DAS) for tomato. Phenthoate was relatively more persistent on tomato than on eggplant.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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