Abstract
The knowledge about mineral content of slim teas is of great importance since the consumption of these beverages has rapidly increased for the past several years. An increasing popularity of these tea products is mainly attributed to their nutritional properties, flavor, taste and health effects. Therefore, the main goal of the present work was to develop a precise and accurate method of the multi-element analysis of slim teas by inductively coupled plasma optical emission spectrometry (ICP OES) without the need for a laborious and tedious sample treatment preceding spectrometric measurements. Five sample preparation procedures, i.e., the total decomposition in a mixture of HNO3 and H2O2 solutions using closed vessel microwave-assisted or open vessel hot-plate systems, the solubilisation in aqua regia or a tetramethyl ammonium hydroxide solution and the extraction in a diluted HNO3 solution, were compared. The performance of the compared procedures was determined in terms of the precision and the accuracy of results achieved and limits of detection of elements. It was found that the solubilisation in aqua regia gave the best results, i.e., limits of detection between 0.15 and 98.4 ng l−1, the precision within 0.6−3.0 % and the accuracy better than 5 %. The developed method of the analysis, being a useful alternative to time-consuming wet digestion procedures, was successfully applied to the analysis of five slim tea products.
Highlights
Nowadays, an interest in the consumption of specific teas can be observed
An extended literature review devoted to sample preparation strategies and the elemental analysis of tea made from leaves Camellia sinensis was presented by Welna et al 2013
The accuracy of the results was assessed by comparing total concentrations of elements obtained using the hot-plate wet digestion (P2), the solubilisation in aqua regia (P3) or tetramethyl ammonium hydroxide (TMAH) (P4) solutions and the extraction in a diluted HNO3 solution (P5) with those achieved using the microwave-assisted digestion procedure (P1)
Summary
An interest in the consumption of specific teas (e.g., slim teas) can be observed These particular teas, being mixtures of different types of teas (black, green or Pu-erh), herbs and various additional bioactive components, are preferred by the people who wish to reduce their body weight. The digestion is carried out by a conventional hot-plate or microwave-assisted heating of tea samples with oxidizing reagents, including HNO3, HNO3+ H2O2, HNO3+H2SO4+ H2O2, HNO3 +H2O2+ HF, HNO3+ HClO4, HNO3 + HCl, HNO3 + HCl + HF,
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have