DETERMINATION OF ARSENIC IN PLANT-TISSUE USING A SLURRY SAMPLING GRAPHITE-FURNACE

Commonly used methods of arsenic (As) determination in plant material require dissolution of tissue in strong acids prior to analysis. Progr ess in the graphite furnace atomic absorption spectrometry (GFAAS) tec hnique has made the determination of metals in solid samples possible. This study was undertaken to evaluate the possibility of As determina tion directly in ground plant tissue using GFAAS. The Perkin-Elmer Mod el 4100 ZL atomic absorption spectrometer with Zeeman background corre ction and AS-70 autosampler has been used for analysis. Spinach (Spina ch oleracea) and corn (Zea mays L.) tissues samples containing various As levels were used as test materials. Before injection of the plant slurry into the furnace, the ultrasonic agitator was used to mix the s lurry in the autosampler cup to assure uniform distribution of plant p owder in the whole volume of liquid. The furnace program contained a p yrolysis step using palladium as the modifier. The GFAAS method was co mpared with the hydride generation method performed on plant tissue di gested with nitric-perchloric acid mixture. Results show that slurry s ampling As values agreed very closely with the standard wet digestion and hydride generation method values. GFAAS is an accurate method, eli minating the time and labor of the plant digestion step.