Determination of chlorpyrifos and some toxic heavy metals in vegetable samples from loei River

Abstract

The research aimed to analyze and compare contents of accumulated residue of chlorpyrifos, chromium, lead and cadmium in five varieties of vegetables in Loei River, Loei Province. Five varieties of vegetables such as Vegetable fern (Diplazium esculentum, Limnocharis flava (L.)), Limnocharis flava (L.) Buch, Lasia spinosa (L.) Thwaites, swamp cabbge (Ipomoea aquatica Forsk) and water mimosa (Neptunia oleracea Lour.) were collected during winter, summer and rainy seasons from Phu Luang, Mueang Loei and Chiang Khan District. Chlorpyrifos was analyzed by high performance liquid chromatography (HPLC). The results showed that the highest chlorpyrifos contents were found in vegetables in winter and summer season in the amount of 0.04±0.00 mg/kg. Analysis of all three heavy metals were carried out dry ashing at 500C and acid digestion with nitric acid prior to analyzing by flame atomic absorption spectrophotometry (FAAS). The results showed that cadmium accumulation in the highest content among all metals in water mimosa (Neptunia oleracea Lour.) in summer season from Phu Luang District (1.83±0.01 mg/kg). The second highest metal content was lead which has found in swamp cabbge (Ipomoea aquatica Forsk) in summer from Mueang Loei District (1.40±0.08 mg/kg). chromium showed the lowest content in Limnocharis flava (L.) Buch in winter from Mueang Loei District (0.47±0.04 mg/kg). The contents of chlorpyrifos and heavy metals were not exceed the legal limits set by International Standard Food and Ministry of Republic Health No.98 of Thailand except Ipomoea aquatica Forsk which collected in summer that showed the lead content higher than the legal limits.