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Detection method of content of lead chrome green in tea leaves

A detection method, art green technology, applied in the direction of Raman scattering, material excitation analysis, etc., can solve the problems that other sources of lead and chromium cannot be ruled out, rapid detection cannot be achieved, and the application range is not wide enough to achieve convenient focusing and speed up Processing speed, effect of avoiding interference

Active Publication Date: 2014-11-05
ZHEJIANG UNIV
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Atomic fluorescence spectrometry has the characteristics of high sensitivity, strong selectivity, small sample amount and simple method; but its disadvantage is that the scope of application is not wide enough
[0008] The above methods all identify the presence of heavy metals lead and chromium, and then infer the content of art green, but in the process of processing, other sources of lead and chromium cannot be ruled out
Therefore, the detection of heavy metals lead and chromium alone cannot determine that lead and chromium must come from art green
Moreover, a large amount of reagents are required for pretreatment when using the above method for detection, the process is cumbersome, and rapid detection cannot be achieved

Method used

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  • Detection method of content of lead chrome green in tea leaves
  • Detection method of content of lead chrome green in tea leaves
  • Detection method of content of lead chrome green in tea leaves

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] A method for detecting art green content in tea leaves, comprising:

[0050] (1) Prepare test samples, use tealeaves with different art green contents as test objects, soak each test object and water for the same time according to a certain ratio; use tea leaves with different art green contents as test objects, soak the tea leaves juice as a test sample,

[0051] Weigh 0.01g, 0.008g, 0.006g, 0.004g, and 0.002g of Art Green into 100ml beakers, then add 1g of tea leaves, stir and mix well with a glass rod, and prepare 5 test objects with content gradients. Then use a measuring cylinder to measure 50ml of boiling water into each beaker, that is, brew the tea leaves and water at a mass ratio of 1:50. After soaking for 10 minutes, pour all the liquid into a 50ml centrifuge tube at a speed of 5000r / min, and centrifuge for 5 minutes. , Pour off most of the supernatant, leave 0.5ml of liquid to re-mix and shake the precipitate on the wall, and use it as a test sample. 15 sam...

Embodiment 2

[0076] Same as embodiment 1, the difference is that after building the calibration model in step (4), it also includes updating the calibration wavenumber and the calibration model, and the update method is as follows:

[0077] Perform variance analysis on the first linear regression model to screen the calibration wavenumber, and use the screened calibration wavenumber as the final calibration wavenumber, and according to the artistic green content of all test samples, and the selected calibration wavenumbers in the Raman spectrum The peak intensity at wavenumber and 520cm -1 The second linear regression model of the content-intensity ratio was constructed as the updated calibration model.

[0078] The variance analysis was carried out on the calibration model, and the results are shown in Table 2

[0079] Table 2

[0080]

[0081] Table 2 shows the wavenumber variable λ 1459 (sample at wavenumber 1459cm -1 Raman spectrum intensity at ) significant level P>0.05, indica...

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Abstract

The invention discloses a detection method of the content of lead chrome green in tea leaves. The method comprises the steps: taking tea juices obtained by soaking tea leaves with different lead chrome green contents as test samples, and acquiring Raman spectra of all the test samples in a set wave number range and with a silicon slice as a substrate; according to the Raman spectra of all the test samples, respectively using a successive projection algorithm and a multivariate linear regression analysis method to determine calibration wave numbers; according to the lead chrome green contents in the tea leaves corresponding to all the test samples, and ratio values of the peak intensities of all the calibration wave numbers to the 520 cm<-1> peak intensity, building a content-strength ratio first linear regression model as a calibration model, and measuring by using the calibration model to obtain the lead chrome green content in a to-be-measured sample. The detection method utilizes the Raman test for analysis, is simple to operate, does not need a tedious and time-consuming sample preparation process, at the same time, avoids interference from other sources so as to ensure the accuracy of the tested the tested lead chrome green, and greatly improves the test accuracy with silicon as a contrast.

Description

technical field [0001] The invention relates to the technical field of art green content detection, in particular to a detection method for art green content in tea. Background technique [0002] The color of tea plays a decisive role in its quality evaluation. This indicator is not only an important basis for tea classification but also an important factor for distinguishing the quality of tea. In recent years, unscrupulous traders have illegally added art green to tea in order to seek profit, so as to achieve the purpose of improving the appearance of tea. Art green is a heavy metal mixed dye, also known as "lead chrome green", "emerald chrome green" or "paint green". An industrial pigment. Its main chemical composition is lead chromate, which is very harmful to the human body and can cause anemia, kidney damage, lead poisoning, dermatitis, eczema, chromic nose disease and skin ulcers, etc. The International Cancer Research Center (IARC) has Include "chromium and certai...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/65
Inventor 李晓丽孙婵骏何勇
Owner ZHEJIANG UNIV
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