engleski

OPTIMIZATION OF THE GFAAS DETERMINATION OF TOXIC ELEMENTS IN BLACK TEA

Infusions derived from tea leaves are one of the most popular beverages in the world. Since vegetation represents a useful indicator of heavy metal contamination in environment via root uptake of metals, it can be used for monitoring pollution across both spatial and temporal scales as documented by Pugh et al. (2002). Due to the elevated ecological awareness nowadays products of organic agriculture are preferably consumed. This organic farming means excluding the use of synthetic inputs, such as synthetic fertilizers and pesticides or genetically modified organisms, but does not refer to the inorganic composition of the soils were the plants are grown. Thus also tea produced by organic agriculture may contain toxic elements, such as cadmium, lead, and arsenic due to metal uptake from polluted soils. The concentrations of these elements should be determined in prepared tea and not only in the leaves or the powder to estimate the possible risk for human health. Since the expected concentrations are very low (&micro ; g/L), as estimated by Onianwa et. al (1999) a highly accurate analytical method is needed that enables their determination. Graphite furnace atomic absorption spectrometry reaches appropriate limits of detections for Cd, Pb and As. Furthermore with this method an enrichment of the analyte is possible by pipetting the sample into the graphite tube several times. Thus the aim of the present study was the optimization of the determination of Cd, Pb, and As by GFAAS. For that reason the temperature programs for Cd, Pb and As were optimized as well as the application of different chemical modifiers was tested.

GFAAS; black tea; lead; cadmium; arsenic

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