ASSESSING THE METHOD OF DETERMINING THE QUANTITY OF METALS IN DRIED STEVIA LEAVES BY ATOMIC ABSORPTION SPECTROPHOTOMETER
Abstract
This study was constructed to develop and validate the recovery, sensitivity and repeatability of the Atomic Absorption Spectrophotometera (AAS) method in the measuring the quatity of metals in dried stevia leaves.The developed method was linear over the concentration ranging 0 - 4 mg/L (Cu, Fe) and 0 – 1 mg/L (Zn, Mn). The correlation coefficient (r) obtained for all metals is higher than 0.99. Limit of detection (LOD) of Cu, Fe, Zn and Mn found was 0,083 ppm, 0.016 ppm, 0.004 ppm and 0,007 ppm respectively. The recovery and repeatability in this method were for determining enough these heavy metals in dried stevia leaves sample. The developed method has been successfully used for determination of Cu, Fe, Zn and Mn levels in dried stevia leaves in Vietnam.
References
Trần Cao Sơn, Phạm Xuân Đà, Lê Thị Hồng Hảo, Nguyễn Thành Trung, Thẩm định phương pháp trong phân tích hóa học và vi sinh, Viện nghiên cứu an toàn vệ sinh thực phẩm quốc gia, 2010.
Crammer, B.; Ikan, R. Progress in the chemistry and properties of the rebaudiosides. In De velopments in Sweeteners; Grenby,T. H., Ed.; Elsevier Applied Science: London, U.K., 1987; pp 45-64.
Eurachem. 1998. The fitness for purpose of analytical method: A laboratory guide to method validation and related topics. Downloaded from: http://www.eurachem.org/guides/pdf/valid.pdf. 18/04/2011.
Lewis, W. H. (1992). Early uses of Stevia rebaudiana (Asteraceae) leaves as a sweetener in
Paraguay. Econ. Bot. 46: 336-337.
Leung, A. Y. and Foster, S. (1996). Encyclopedia of common natural ingredients Ð used in food,
drugs and cosmetics (2nd ed.). New York: John Wiley and Sons, Inc. 2, 478.
Miller J.C and Miller J. N, Statistics for Analytical Chemistry. Ellis Horwood Limited, 1988.
Soejarto, D. D., Compadre, C. M., Medon, P. J., Kamath, S. K. and Kinghorn, A. D.
(1983). Potential sweetening agents of plant origin. II. Field search for sweet-tasting Stevia
species. Economic Botany 37(1): 71-79.
