Title : " Determination of Carbaryl in Treated Vegetables by High Performance Liquid Chromatography”

Researcher : Chumni Sangphagdee and Mongkon Rayanakorn

Office of Researcher : CHEMISTRY


Determination of cerbaryl in vegetables was carried out using a high performance liquid chromatrography (HPLC) method. Prior to HPLC analysis, 40 g of each vegetable sample were sonicated for 2 minutes in 100 ml of methanol in order to remove the pesticide. A 5 ml aliquot was combined with 245 ml water and passed through a disposable solid phase extraction cartridge, packed with 1 g of C 18-bonded silica (40 m m. particle size), which selectively retained slightly non polar compounds. The reserved phase HPLC separation was accomplished with m Bondapak C18 column and 50%(v/v) acetonitrile-water as the eluent. Detection was performed at 220nm. The detection limit and the lower limit of determination were found to be 0.8 ppb and 1.4 ppb, respectively. The detector linearlty range was found to be in the range of 0.8 ng to 2.4 g of cabaryl injected. Average recoveries for 2 kinds of theanalyzed vegetables were 93.6% with coefficient of variation of 1.8% at 1 m g/g concentration and 84.2% with coefficient of variation of 1.8% at 1 m g/g concentration.

The amount of carbaryl found on different day intervals were found to have varied with time. No carbaryl was detected on the day before spraying and 25 days after spraying while the average highest amount of carbaryl found amounting to 35.0 mg/kg was taken from vegetables collected on the day directly after spraying. Conpared to the maximum residue limit values imposed in Germany and Thailand as 3.0 mg/kg, respectively , the highest amount of carbrayl found was a rather high figure. However, in terms of the WHO acceptable daily intake value in a hypothetical situation, the consumers of these carbaryl treated vegetables would face no potential health risk if the crops were harvested 12 days or more after spraying and proper pre-treatment of the crops was taken before eating.

Presented at : The 1st International Conference on Water Resources Management In Intermontane Basins, Chiang Mai, 2-6 February 1999.