Simultaneous Determination of Sodium, Potassium, Manganese and Bromine in Tea by Standard Addition Neutron Activation An
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Simultaneous Determination of Sodium, Potassium, Manganese and Bromine in Tea by Standard Addition Neutron Activation Analysis Mohamad Khayatzadeh Mahani & Mohamad Ghanadi Maragheh
Received: 13 September 2009 / Accepted: 25 November 2009 / Published online: 17 December 2009 # Springer Science+Business Media, LLC 2009
Abstract Standard addition method was applied for neutron activation analysis of tea leaves. Four brands of tea leaves were analyzed for its Na, K, Mn, and Br contents by this method. The Na, K, Mn, and Br concentrations were found to be in the 90–120µg/g, 1.8–2.1% w/w, 150–500 and 3–7µg/g ranges, respectively. The extraction efficiency of these elements, during the infusion, was calculated by analysis of tea leaves before and after the infusion process. It was observed that about 90% of the Na, K, and Br elements were extracted to water during the infusion process. The drinking tea is a rich source of Mn (despite of an extraction efficiency of 50% for this element). Keywords Neutron Activation Analysis . Standard Addition . Tea . Essential Elements . Infusion
Introduction The processed leaves of the Camellia sinenis were used as green and black tea having different processing steps. Tea infusions are among the popular hot drinks around the world (Ødegård and Lund 1997; Stagg and Millin 1975). The chemical composition of tea leaves is very complex and consists of flavonols, alkaloids, enzymes, minerals, trace elements, and others (Jha et al. 1996). During the infusion process, in addition to water soluble organic compounds, major and trace elements of tea leaves were extracted by water. Many of these elements influence the taste of the tea infusion, play a vital role in metabolic M. K. Mahani (*) : M. G. Maragheh Jaber Ibn Hayan Research Laboratories, NFCRS, NSTRI, P.O. Box 11365-3486, Tehran, Iran e-mail: [email protected]
processes, and are essential for the general well being of humans. Deficiency or excess of these elements may cause disease and/or be deleterious to health (Feng et al. 2003; O’Dell and Sunde 1997). Several elements, such as Ca, Na, K, Mg, and Mn, are present at milligrams per gram level, whereas elements such as Cr, Fe, Co, Ni, Cu, Zn, and Cd are present at a few micrograms per gram (Cao et al. 1998; Kumar et al. 2005; Matsuura et al. 2001; Ødegård and Lund 1997). Also, there are some reports on the presence of rare earth elements in tea infusions at nanograms per gram level (Cao et al. 1998). Due to the importance of the minerals present in tea, many studies have been carried out to determine their levels in leaves and tea infusions by using spectrophotometry (Liu et al. 1995), atomic absorption spectrometry (Hazer et al. 2009; Kendüzler and Türker 2005; Moghaddam et al. 2008; Pohl and Prusisz 2006; Soylak et al. 2007), atomic fluorescence spectrometry (Duan et al. 2005), inductively coupled plasma atomic emission spectrometry (Lamble and Hill 1995; Marchisio et al. 2005; Matsuura et al. 2001; Mokgalaka et al. 2004), inductively coupled plasma mass spectrometry (Cairns et al.
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