A comparison of samples preparation strategies in the multi-elemental analysis of tea by spectrometric methods

Tea made from Camellia sinensis plant is one of the most widely consumed beverages worldwide. It is recognized as a rich source of various elements, including those being essential to human health and also toxic that the plant may accidentally take up during the growth period and which can have adverse effects on the human well-being. Due to the habitual drinking of tea infusions, the determination of the mineral content in tea is of a great importance in order to control the quality and the safety of this product or to judge its nutritional value. In general, atomic and mass spectrometries are commonly used for the elemental analysis of tea leaves and commercial teas. Although these analytical techniques are useful in measurements of the total concentration of elements, they usually require samples to be properly pre-treated prior to spectrochemical measurements. Because the sample preparation of tea is the most critical step of the whole analytical chain, this review has been attempted to survey different preparation procedures of tea samples carried out before the element analysis. Common strategies aimed at decomposing samples through dry and wet digestions are described in details and compared in reference to their advantages and drawbacks. Recent, alternative methods of the sample treatment and the analysis by spectrometry techniques are also highlighted. The effect of the selection of certain sample preparation procedures on the reliability of analytical results and manners of the control and the assurance of their quality are also considered. (C) 2013 Elsevier Ltd. All rights reserved.