尼日利亚市场上销售的干茶和草本茶中痕量金属的化学形态及特征分析
Chemical Speciation and Characterization of Trace Metals in Dry Camellia sinensis and Herbal Tea Marketed in Nigeria.
作者信息
Fred-Ahmadu Omowunmi H, Adedapo Adebusayo E, Oloyede Mary O, Benson Nsikak U
机构信息
Analytical and Environmental Chemistry Unit, Department of Chemistry, Covenant University, Ota, Ogun State, Nigeria.
出版信息
J Health Pollut. 2018 Sep 10;8(19):180912. doi: 10.5696/2156-9614-8.19.180912. eCollection 2018 Sep.
BACKGROUND
Trace metals from anthropogenic activities have been found to occur in tea brands and pose potential human health risks to consumers.
OBJECTIVES
The present study assessed the concentrations of trace metals in green, black and herbal tea brands using a modified Community Bureau of Reference sequential extraction method.
METHODS
Fifteen (15) and eight (8) herbal tea samples commonly consumed in Nigeria were collected and analyzed for trace metals. The concentrations of cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) in extract fractions were analyzed using microwave plasma atomic emission spectroscopy (MP-AES).
RESULTS
Trace metals were detected in all of the samples investigated. The concentrations of trace metals in 4 stages (soluble/exchangeable/carbonates bound fraction, reducible fraction, oxidizable fraction, residual fraction) of sequential and pseudo-total metal extraction procedures are presented. The concentrations of Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn in the exchangeable/carbonate bound fraction for green tea ranged between 0.27-1.47, ND-0.33, ND-0.44, 7.05-33.04, 0.23-0.69, ND-0.51, ND-0.16 and 0.18-1.99 mg/kg, ND-0.73, 0.15-0.36, 0.36-0.59, 1.38-30.07, 0.15-0.54, 0.05-0.76, 0.15-0.34 and 0.27-0.77 mg/kg and 0.54-0.64, 0.25-0.41, 0.35-0.47, 18.72-23.98, 0.30-0.55, 0.15-0.21, 0.15-0.23 and 0.30-0.48 mg/kg for hebal tea, respectively.
CONCLUSION
The metal content in the investigated tea indicated low to enhanced concentrations. Locally produced black teas recorded relatively low trace metal contents compared to the green and herbal tea samples. The most bioavailable trace metal was Mn, while Zn was most preferably bound to the residual fraction. Cadmium, Cr, Cu, Ni, Pb, and V were distributed at varied concentrations among other extractable phases. Daily consumption of the investigated tea products may expose consumers to potentially toxic metals as well as essential elements.
COMPETING INTERESTS
The authors declare no competing financial interests.
背景
已发现来自人为活动的痕量金属存在于茶叶品牌中，并对消费者构成潜在的人类健康风险。
目的
本研究采用改进的欧洲标准局连续萃取法评估绿茶、红茶和花草茶品牌中痕量金属的浓度。
方法
收集了尼日利亚常用的15种绿茶和8种花草茶样品，并对其痕量金属进行分析。使用微波等离子体原子发射光谱法（MP-AES）分析萃取组分中镉（Cd）、铬（Cr）、铜（Cu）、锰（Mn）、镍（Ni）、铅（Pb）、钒（V）和锌（Zn）的浓度。
结果
在所研究的所有样品中均检测到痕量金属。列出了连续萃取和准总量金属萃取程序4个阶段（可溶/可交换/碳酸盐结合态组分、可还原态组分、可氧化态组分、残留态组分）中痕量金属的浓度。绿茶可交换/碳酸盐结合态组分中Cd、Cr、Cu、Mn、Ni、Pb、V和Zn的浓度范围分别为0.27 - 1.47、未检出 - 0.33、未检出 - 0.44、7.05 - 33.04、0.23 - 0.69、未检出 - 0.51、未检出 - 0.16和0.18 - 1.99mg/kg，花草茶分别为未检出 - 0.73、0.15 - 0.36、0.36 - 0.59、1.38 - 30.07、0.15 - 0.54、0.05 - 0.76、0.15 - 0.34和0.27 - 0.77mg/kg，以及0.54 - 0.64、0.25 - 0.41、0.35 - 0.47、18.72 - 23.98、0.30 - 0.55、0.15 - 0.21、0.15 - 0.23和0.30 - 0.48mg/kg。
结论
所研究茶叶中的金属含量显示出低至增强的浓度。与绿茶和花草茶样品相比，本地生产的红茶痕量金属含量相对较低。生物可利用性最高的痕量金属是Mn，而Zn最易与残留态组分结合。Cd、Cr、Cu、Ni、Pb和V以不同浓度分布在其他可萃取相中。每日饮用所研究的茶产品可能使消费者接触潜在有毒金属以及必需元素。
利益冲突
作者声明无相互竞争的财务利益。
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