Method for measuring Cr of tea by combining ASE (accelerated solvent extraction) and IC-ICP-MS, and application

Abstract

The invention discloses a method for measuring Cr of tea by combining ASE (accelerated solvent extraction) and IC-ICP-MS, and application. The method comprises the following steps: 1) performing ASE on a tea sample, adding an EDTA disodium salt and ammonium nitrate solution of 0.04 mol*L<-1> with the pH value being 7.0 to 7.5, and performing extraction at 80 DEG C and under the pressure of 1600 psi; 2) separating to-be-measured liquid by using ion chromatography; and 3) measuring the concentration of Cr(III) and Cr(VI) by using ICP-MS. The method is applied to monitoring of the change of chromium in the processing process of broken black tea, evaluation on the contamination situation of a cut-up metal rotor on the chromium in the broken black tea or tea original traceability research. An innovation scheme is provided for extraction, separation and measurement of the chromium (III) and the chromium (VI) in the tea, and both timeliness and stability are taken into consideration, so high accuracy, precision and repeatability are achieved; and in addition, the method is low in cost and suitable for automatic operation. The method can be applied on a large scale, so that data in different regions, time or processes has comparability, and networking monitoring, big data mining analysis and the like can be further conducted.

Description

technical field [0001] The invention relates to content determination and application of chromium metal element in tea. Background technique [0002] Chromium is widely and sparsely distributed in nature, and exists in almost all substances. Chromium can form a variety of valence compounds from -2 to +6 in nature, the most common being Cr(Ⅲ) and Cr(Ⅵ). For chromium, trivalent Cr is an essential element for the human body and participates in various physiological activities of the human body, while hexavalent Cr is highly toxic. The total chromium limit for tea in NY659-2003 standard is 5.0 mg / kg, but this does not reflect the potential harm of chromium in tea to the human body, and further determination of trivalent and hexavalent chromium is needed. [0003] Due to the influence of the pH of the extraction solution, it is difficult to extract and measure chromium (Ⅲ) and chromium (Ⅵ) at the same time. Due to the increase of the oxidation-reduction potential in a low pH en...

AI Technical Summary

Problems solved by technology

[0004] It is difficult to accurately measure Cr(Ⅲ) and Cr(Ⅵ) at the same time with a single instrument detection technology, and the use of combined technology is an important research method for element speciation analysis (Joanna Shaofen etc., Analytical sciences, 2004,20:841-846 )

However, at present, there is still a lack of methods with good accuracy, precision and repeatability for the determination of chromium metal elements in tea, which cannot adapt to the development trend of networked big data and intelligent monitoring.

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