engleski

Determination of Selected Toxic Elements in Black Tea by GFAAS

Tea infusions represent one of the most popular beverages in the world. The elevated ecological awareness nowadays leads to a higher consumption of products of organic agriculture. Organic farming means excluding the usage of synthetic inputs, such as synthetic fertilizers and pesticides or genetically modified organisms. Nevertheless a not negligible uptake of metals from the soil where the tea plants are grown may occur. Thus also tea produced by organic agriculture may contain toxic elements, such as cadmium, lead, and arsenic. In the presented work the concentrations of these elements were determined in prepared tea as well as in the tea leaves or the tea powder to estimate the possible risk for human health. Since the expected concentrations were very low (µg/L), a graphite furnace atomic absorption spectrometry method (GFAAS) was optimized for the determination of Cd, Pb and As. The optimized pre-treatment and atomization temperatures were 500°C and 1400°C for Cd, 800°C and 1650°C for Pb, 1050°C and 2200°C for As. Only for the determination of Cd chemical modifiers (50 µg of PO43- and 3 µg of Mg(NO3)2) were necessary to reach the low required LODs. The method was then applied for the quantification of Cd, Pb and As in tea samples from classical as well as from organic farming, whereby tea powder and prepared infusions were analyzed. The results for classical and organic farming tea were compared and the extraction yield for each element was calculated.

cadmium; lead; arsenic; tea; GFAAS

nije evidentirano