Department of Analytical Chemistry and Chemical Metallurgy, Faculty of Chemistry, Wroclaw University of Technology, Smoluchowskiego 23,, 50-372, Wroclaw, Poland.
Biol Trace Elem Res. 2020 May;195(1):272-290. doi: 10.1007/s12011-019-01828-x. Epub 2019 Jul 24.
A fast and straightforward sample preparation procedure of the dialyzable fraction of infusions of teas prior to their analysis on Al, Ba, Ca, Cu, Fe, Mg, Mn, Ni, Sr, and Zn contents by flame atomic absorption spectrometry (FAAS) and inductively coupled plasma optical emission spectrometry (ICP OES) was developed and validated. The proposed methodology was based on acidification with HNO only and demonstrated good analytical performance, i.e., precision (0.80-5.0%), accuracy (< 5%), recoveries of elements (97.4-105%), and their detection limits (0.075-1.1 μg L) along with linearity of calibration curves in the whole studied concentration ranges. Applicability of the evaluated procedure, being a useful alternative to time-consuming wet digestions, was tested by determining bioaccessibility of elements in 20 infusions of black (BT) and green (GT) teas as assessed with the aid of in vitro gastrointestinal digestion. Average contributions of bioaccessible fractions (%) of studied metals were as follows: 1.18 (Al)-40.7% (Ca) and 4.65% (Al)-46.3% (Ca) for BTs and GTs, respectively. Drinking daily four cups (1 L) of tea, recommended dietary intakes (RDIs) of Ca, Cu, Fe, Mg, and Zn were covered to a small degree (< 1.5%). Only bioaccessibility of Mn highly contributed to RDI for this metal. According to provisional tolerable weekly intakes (PTWIs) for toxic elements such as Al and Ni, consumption of both types of teas should not represent any health risk. Additionally, analysis of variance of results clearly indicated that BTs and GTs were mostly differentiated due to concentrations of the bioaccessible fraction of Al, Ba, Cu, and Ni.
本研究开发并验证了一种快速、直接的茶浸提液可透析部分的样品前处理方法，用于火焰原子吸收光谱法（FAAS）和电感耦合等离子体光学发射光谱法（ICP OES）分析其中的 Al、Ba、Ca、Cu、Fe、Mg、Mn、Ni、Sr 和 Zn 含量。该方法基于仅用 HNO3 酸化，具有良好的分析性能，例如精密度（0.80-5.0%）、准确度（<5%）、元素回收率（97.4-105%）及其检测限（0.075-1.1μg L）以及校准曲线在整个研究浓度范围内的线性。该评估方法的适用性通过使用体外胃肠道消化来评估 20 种黑茶（BT）和绿茶（GT）浸提液中元素的生物可利用性来测试，这是一种替代耗时的湿法消解的有用方法。研究金属的生物可利用部分（%）的平均贡献如下：BTs 为 1.18（Al）-40.7%（Ca）和 4.65%（Al）-46.3%（Ca），GTs 分别为 4.65%（Al）-40.7%（Ca）和 4.65%（Ca）。每天饮用四杯（1L）茶，可满足 Ca、Cu、Fe、Mg 和 Zn 的推荐膳食摄入量（RDIs）的一小部分（<1.5%）。只有 Mn 的生物可利用性对该金属的 RDI 贡献较大。根据暂定每周耐受摄入量（PTWIs），对于 Al 和 Ni 等有毒元素，消费这两种类型的茶不应构成任何健康风险。此外，方差分析结果清楚地表明，BTs 和 GTs 主要是由于可透析部分的 Al、Ba、Cu 和 Ni 浓度而区分的。
