Determination of Amitraz Residue in Fruits by High Performance Liquid Chromatography

SU-HSIANG TSENG*, PI-CHIOU CHANG AND SHIN-SHOU CHOU

 National Laboratories of Foods and Drugs, Department of Health, Executive Yuan, 161-2, Kuen Yang Street, Nankang 115, Taipei, Taiwan, R.O.C. 

ABSTRACT

   A high performance liquid chromatographic method (HPLC) for the determination of amitraz residue in fruits has been developed. Twenty grams of sample and 2g of sodium hydrogen carbonate were weighed and homogenized with acetone. After vacuum filtration, 1g NaCl was added and partitioned with n-hexane containing 20% ethyl acetate. The organic layer was evaporated to 5 mL and applied on a florisil cartridge. The cartridge was eluted with 10 mL n-hexane:ethyl acetate (8:2, v/v), and the eluate was evaporated to dryness. The residue was dissolved in acetonitrile and determined by HPLC equipped with a UV detector. Separation was conducted with a Lichrosorb RP-18 column using acetonitrile: H2O (80:20, v/v) as mobile phase to separate amitraz and interferences, and amitraz was determined at 313 nm wavelength. Recovery studies were carried out by spiking the amitraz standards to the levels of 0.25~0.75 ppm in apples and 0.1~0.3 ppm in grapefruit. The average recoveries were 88.8~92.1% and 87.2~90.9% for apples and grapefruit, respectively. The detection limit was 0.02 ppm.

Key words: amitraz, high performance liquid chromatography (HPLC), florisil cartridge, fruit