Application of high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS): determination of trace elements in tea and tisanes

Abstract

A new application of HR-CS FAAS (High Resolution-Continuum Source Flame Atomic 12 Absorption Spectrometry) has been developed for the determination of several trace elements (Ca, 13 Co, Cu, Fe, Mn, Ni, Na and Zn) in infusions made from tea, rooibos and tea with seaweed samples. 14 The proposed methods are fast, inexpensive and show good performances: the mean analytical 15 recovery was aproximately 100 %. The mean limit of detection was 29.4 μg/l, and the mean limit of 16 quantification was 98.0 μg/l (both limits refer to the brewed samples). Due to the matrix effect 17 observed, the standard addition method had to be applied. Preliminary classification (based on 18 metal contents) using chemometric techniques such as PCA (Principal Component Analysis) and 19 CA (Cluster Analysis), was successful for infusions made from rooibos and tea with seaweed, but 20 inconclusive for black and green teas.