Residues of synthetic pyrethroid pesticides in vegetables, fruit, sediment and water from an intensive agricultural area (Fang district, Chiang Mai, Thailand)

Abstract

This study was conducted in four intensive agricultural areas of the Fang district, Chiang Mai, northern Thailand. The objective of this study was to determine synthetic pyrethroid residues in vegetable, fruit, sediment, and surface water samples. Fruit and vegetables were purchased from local markets in the study areas. The vegetables in this study included cabbage, kale, water spinach, cauliflower, Chinese cabbage, Chinese mustard, yard long bean, cucumber, and sugar pea, while the fresh fruit included tangerine, guava, apple, dragon fruit, mango, sand pear, rose apple, lychee and grape. Sediment and surface water samples were collected from main streams of the four studied areas. The pyrethroid residues in vegetables, fruit, and sediment samples were extracted with dichloromethane in an ultrasonic bath and cleaned up on a graphite carbon cartridge. Liquid - liquid extraction technique was used to prepare pyrethroid compounds from surface water samples. The extracted samples were determined by using gas chromatography - electron capture detection (GC-ECD). Six synthetic pyrethriod pesticides in this study consist of lambda cyhalothrin, permethrin, cyfluthrin, cypermethrin, fenvalerate, and deltamethrin. Cypermethrin was found to be the highest detection percentage in surface water, vegetables, and fruit samples at 33.3, 75.8 and 95.3%, respectively. Meanwhile, permethrin was the highest detection percentage in sediment samples at 66%. However, lambda cyhalothrin was detected in sediment and surface water samples with the highest levels at 0.38 and 1.61 mg/kg, respectively. Deltamethrin was detected in vegetable samples with the highest level at 9.97 mg/kg and cypermethrin was detected in fruit samples with the highest level at 11.83 mg/kg. Furthermore, this study is an application of the developed method providing a high sensitivity with the limit of detection (LoD) of permethrin at 0.11 mg/kg, cyfluthrin at 0.11 mg/kg, fenvalerate at 0.22 mg/kg, lambda cyhalothrin at 0.26 mg/kg, cypermethrin at 0.51 mg/kg and deltamethrin at 0.65 mg/kg. © 2011 WIT Press.