A Novel Isoenzyme based Rapid, Inexpensive Method to Detect the Presence of Specific Insecticide Residues in Fruits and Vegetables.

Suhani Jain & Divya Kranthi

Suhani Jain & Divya Kranthi
Center Point School, Nagpur, Maharashtra
Title: A Novel Isoenzyme based Rapid, Inexpensive Method to Detect the Presence of Specific Insecticide Residues in Fruits and Vegetables.
Hazardous insecticides are sprayed indiscriminately on food crops & vegetables for insect control. In general, cheaper insecticides belonging to four major groups (organophosphates, carbamates, synthetic pyrethroids & neonicotinoids) are used. These insecticides at low concentrations in food are directly harmful to humans and ecosystems. There is no quick method available to detect insecticide residues. We developed a simple, reliable 30-min test to precisely detect insecticide residues of specific groups, based on the principle that specific carboxylesterase iso-enzymes inhibit specific insecticides and the extent of inhibition, directly indicates the quantity of insecticide. Purified iso-enzymes were immobilized on nitrocellulose membranes to retain activity for at least one month under normal storage in paper packets at room temperature. We standardized the method to detect insecticide residues above the maximum residue limits of the WHO (World Health Organisation).
Carboxylesterase (EC 3.1.1.1) iso-enzymes catalyse hydrolysis of carboxylic esters to free acid anions and alcohol. Insecticide resistant insects contain unique iso-enzymes that metabolize insecticides of specific groups. In the process of metabolism, these are inhibited by insecticides in a dose dependent manner. Presence or absence of specific insecticides in unknown test samples can be determined by examining the residual iso-enzyme activity on the enzyme bound nitrocellulose membranes after dipping them in the unknown test sample solution obtained by rinsing vegetables. Thus, through this simple test, we can detect the presence of specific insecticide residues in fruits and vegetables.