Determination of mercury, cadmium and lead contents in different tea and teas infusions (Camelia sinensis, L.)

Ľuboš Harangozo,Július Árvay,Martin Hauptvogl,Ján Tomáš

doi:10.5219/510

Ľuboš Harangozo, Július Árvay + Show 2 more

Open Access

https://doi.org/10.5219/510

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Abstract

The present paper deals with assessing the level of contamination of green (n = 14) and black - fermented (n = 10) teas of different origins (country of origin) (China, India, Japan, Nepal and Taiwan), which are normally available in Slovakia. The contents of the studied contaminants (mercury, cadmium and lead) were observed in samples of dried teas and their infusions. The contaminant contents were investigated by atomic absorption spectrometry with Zeeman background correction and a graphite furnace GF-AAS (Cd, Pb). The total mercury content was analyzed by CV-AAS method. Concentrations of the studied contaminants in the dried tea samples were as follows: green tea: Hg: 0.0027 ±0.0010 mg.kg-1 (median ± standard deviation); Cd: 0.161 ±0.084 mg.kg-1, Pb: 0.875 ±0.591 mg.kg-1, black tea: Hg: 0.0022 ±0.0014 mg.kg-1, Cd: 0.397 ±0.077 mg.kg-1, Pb: 1.387 ±0.545 mg.kg-1. The contents of the contaminants in the tea infusions were as follows: green tea: Hg: 0.03 ±0.04 μg.L-1, Cd: 0.278 ±0.068 μg.L-1, Pb: 1.975 ±0.503 μg.L-1, black tea: Hg: 0.050 ±0.080 μg.L-1, Cd: 0.291 ±0.054 μg.L-1, Pb: 1.955 ±1.264 μg.L-1. According to the currently valid maximum limits for a particular contaminant in Slovakia, it can be stated that the health standards were not exceeded in any of the tea samples. The limit value of the lead content (2.0 mg.kg-1 DM) was exceeded (by 12.4%) only in one sample of the dried black tea from China (Yunnan - Golden Snow), however it is the limit value valid in China. The results of the analysis of 24 tea samples show that even regular consumption does not pose a health risk to consumers.

Highlights

Tea (Camellia sinensis, L.) is one of the most popular non-alcoholic beverages consumed by over two-third of the worlds population due to its medicinal, refreshing and mild stimulant effects
Higher concentrations of mercury were recorded in green teas compared with black – fermented teas, which is caused by technological processes
The maximum allowable levels of the monitored contaminants defined by the legislative standards of China, and/or Codex Alimentarius of Slovakia were not exceeded in the results of the Hg content in the tea samples

Summary

Introduction

Tea (Camellia sinensis, L.) is one of the most popular non-alcoholic beverages consumed by over two-third of the worlds population due to its medicinal, refreshing and mild stimulant effects. In order to assess the level of contamination of the dried green and black teas, the results of the studied contaminant contents were compared with maximum allowable levels (MAL) of the contaminants that are listed in relevant legislative regulations valid in China and Slovakia. Almost identical results of mercury content in Pu-Erh teas (fermented teas) recorded Cao et al, (2010), who found in 17 samples concentration interval of 0.0002 – 0.0390 mg.kg-1 with an average of 0.0030 mg.kg-1.

Results

Conclusion