Determination of ten kind of metal elements in different varieties of Jiangxi famous tea

Authors

KE Fa-jun, Key Laboratory of Agricultural Products Processing and Quality Control of Nanchang City, Nanchang, Jiangxi 330045 , China ；Department of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi 330045 , China
YANG Wu-ying, Key Laboratory of Agricultural Products Processing and Quality Control of Nanchang City, Nanchang, Jiangxi 330045 , China ；Department of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi 330045 , China
WANG Dan, Key Laboratory of Agricultural Products Processing and Quality Control of Nanchang City, Nanchang, Jiangxi 330045 , China ；Department of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi 330045 , China
HONG Yan-ping, Key Laboratory of Agricultural Products Processing and Quality Control of Nanchang City, Nanchang, Jiangxi 330045 , China ；Department of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi 330045 , China
CHEN Xin-zhu, Key Laboratory of Agricultural Products Processing and Quality Control of Nanchang City, Nanchang, Jiangxi 330045 , China ；Department of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi 330045 , China
WANG Yu-bo, Key Laboratory of Agricultural Products Processing and Quality Control of Nanchang City, Nanchang, Jiangxi 330045 , China ；Department of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, Jiangxi 330045 , China

Abstract

Firstly, orthogonal test design was adopted to optimize the best working conditions (acetylene flow, hollow cathode lamp flow, burner height) of atomic absorption spectrometry for the eight kinds of essential elements, including potassium, calcium, sodium, magnesium, iron, copper, manganese, and zinc. Single-factor experimental design was adopted to optimize the best working conditions (ashing temperature, ashing time, atomization temperature, atomization time) of graphite furnace atomic absorption spectrometry for the two toxic elements of lead and cadmium. Thereafter, the standard curve of atomic absorption spectrometry for each element under the best working conditions of the instrument was established, and the detection limit and precision of the method were investigated. The sample pre-treatment conditions were optimized. Under the control of the optimal sample pre-treatment conditions, the sample spiked recovery rate was determined, and flame atomic absorption spectrometry of eight essential elements and graphite furnace atomic absorption spectrometry of two toxic elements that meet the requirements of detection were established. Finally, the corresponding ten elements in eight Jiangxi famous teas were determined by these established methods and further compared. The results showed that these established atomic absorption spectrophotometry methods all had good linear relationship in the corresponding concentration range. The correlation coefficients were 0.991 8~0.999 2, and the precision RSD values ranged from 0.77% to 3.32%, with the detection limits of 0.004~0.050 g/mL and the recovery rates of 99.25%~102.25%. The results showed that some significant differences in the contents of the ten kinds of elements in the eight types of tea were found, with a certain order, i. e. K ＞ Mg ＞ Mn ＞ Ca ＞ Fe ＞ Na ＞ Zn ＞ Cu ＞ Pb ＞ Cd. Suichuan Gougunao tea contains the highest contents of K, Ca, and Fe and Lushan Yunwu tea has the highest Na content. The highest Mg and Zn contents are Jing'an white tea. The highest Mn content is Jinggangshan green tea. Wuyi black tea was found to contain the highest Cu content, while Pb and Cd contents are lower in eight types of tea. These atomic absorption spectrometry methods established in this study are easy to operate, and have less interference and high sensitivity, which also can be used for the determination of the corresponding element content in various other tea. The contents of four kinds of the constant elements of potassium, calcium, sodium, magnesium and four kinds of trace elements of iron, copper, manganese, and zinc, are rich in eight types of famous Jiangxi teas. However, the contents of two kinds of toxic elements, Pb and Cd, are lower than national standards.

Publication Date

7-28-2020

First Page

72

Last Page

77

DOI

10.13652/j.issn.1003-5788.2020.07.015

Recommended Citation

Fa-jun, KE; Wu-ying, YANG; Dan, WANG; Yan-ping, HONG; Xin-zhu, CHEN; and Yu-bo, WANG (2020) "Determination of ten kind of metal elements in different varieties of Jiangxi famous tea," Food and Machinery: Vol. 36: Iss. 7, Article 15.
DOI: 10.13652/j.issn.1003-5788.2020.07.015
Available at: https://www.ifoodmm.cn/journal/vol36/iss7/15

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