Rapid bioassay of pesticide residues in vegetables from various outlet markets in Laguna area [Philippines].
1994
Tipa E.V. | Tejada A.E. | Barril C.R. | del Rosario E.J. | Mercado B.T. | Quintana B.B.
A rapid bioassay technique developed by Taiwan Agricultural Institute for the detection of organophosphates and carbamates residues using acetylcholinesterase from housefly head was used for screening residues in vegetables: cabbage, pechay, okra, bittergourd, tomatoes, eggplant, string beans, Baguio beans and Chinese pechay. Of the 168 samples assayed, 11.3 percent have positive results with a permissible error of 20 percent. Any sample with inhibition greater than 20 percent is considered positive of residues, an undeniable evidence of the presence of pesticide residues. Confirmatory analysis by gas chromatography indicated residues of chlorpyrifos, diazinon, malathion, methyl parathion and triazophos. Residue levels of methomyl (1.3 mg/kg), diazinon (0.67 mg/kg) and triazophos (0.69 mg/kg) in tomatoes, pechay and eggplant exceeded the Maximum Residue Limits (MRL) set by the FAO/WHO which is 0.5, 0.5 and 0.1 mg/kg, respectively. Crude enzyme from housefly head and partially purified enzyme from Taiwan Agricultural Research Institute were comparable with enzyme activity of 1.09 x 10 to the minus 2 micro mole/min. ml and 1/02 x 10 to the minus 2 micro mole/min.-ml, respectively.
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