Determination of Copper in Edible Oils by Direct Graphite Furnace Atomic Absorption Spectrometry

 SYR-SONG CHEN*, CHING-MEI CHEN, CHIEU-CHEN CHENG 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 simple method for determination of copper in edible oils was developed, using a polarized Zeeman graphite furnace atomic absorption spectrophotometer and a pyro graphite tube. Edible oils were diluted with 2% lecithin-cyclohexane and analyzed directly by the standard addition method. The optimal ashing and atomizing temperatures were 900℃ and 2700℃, respectively. A standard solution diluted with 2% lecithin-cyclohexane was superior to salad oil or cyclohexane. Results were best measured when the concentration of lecithin in cyclohexane was higher than 2%. The detection limit of this method was 2.0 ng/mL. The respective range of recovery of copper was 85.5~90.0% and 86.0 ~ 93.0% in salad oil and lard which were fortified with 10, 20 and 40 ng Cu/mL respectively using the standard addition method.

Key words: graphite furnace atomic absorption spectrophotometer, copper, edible oils and fats