RESIDUES DETERMINATION OF METHOMYL AND PROFENOFOS INSECTICIDES IN FRESH FRUITS AND VEGETABLES BY UV SPECTROPHOTOMETRIC, HPLC, AND ACHE-BIOSENSOR TECHNIQUES
AHMED F. EL-ASWAD
Department of Pesticide Chemistry and Technology, Faculty of Agriculture, Alexandria University, El-Shatby, Alexandria 21545, Egypt
MOHAMED E. I. BADAWY *
Department of Pesticide Chemistry and Technology, Faculty of Agriculture, Alexandria University, El-Shatby, Alexandria 21545, Egypt
*Author to whom correspondence should be addressed.
Abstract
The pesticides are widely used through the world as they are considered economically important for improving quality and quantity of agricultural products. The insecticides profenofos (organophosphorus) and methomyl (carbamate) are marketed commercially in Egypt and used for foliar treatments of fruits and vegetables according to the Egyptian Agricultural Ministry. The risk of having higher residues in vegetables and fruits is considerable. Therefore, the aim of the present study addresses the problem related to the lack of rapid, cost-effective and high-quality analytical method to detect such pesticide residues in fruits and vegetables and obtain removal treatment of the residues that suitable for organizations, exporters, consumer groups, and housewives. The results indicated that the AChE technique as a biosensor of the tested insecticide residues was the highest sensitive one compared with UV Spectrophotometer and HPLC. The average of insecticide residues in different samples determined by AChE technique was higher by factor of 9.15 and 5.39 for methomyl and 8.08 and 5.46 for profenofos than that determined by UV Spectrophotometer and HPLC, respectively. In addition, the tested biosensors based on the inhibition of AChE is very sensitive, rapid detection, long-term active and very suitable for use as disposable sensor. On the other hand, our results indicated that the washing with tap water remove approximately 50% of the profenofos residue and all treatments removed higher than 75 % of the methomyl residue in all kind of the samples. Moreover, the washing with acetic acid solution (1%) or sodium chloride solution (5%) removed magnitude amounts of the residues from treated samples and lead to the residue level lower than the Maximum Residue Limits (MRLs). In general, washing the vegetables and fruits with suitable solution before using has to be strictly considered by the consumer.
Keywords: Residue analysis, methomyl, profenofos, bioactive paper-based AChE, UV, HPLC