Raid detection method for heavy metal lead in tea leaves

A detection method, heavy metal technology, applied in the direction of material analysis by observing the influence of chemical indicators, and analysis by making materials undergo chemical reactions, which can solve problems such as difficult and rapid detection

Inactive Publication Date: 2012-07-04
CHINA JILIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The present invention solves the problem that the traditional heavy metal lead detection uses large-scale precision instruments and equipment or highly toxic substances such as potassium cyanide, and it is difficult to apply it to the rapid detection of food, water samples and other samples, and provides a convenient and fast tea in- Heavy metal lead detection method

Method used

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  • Raid detection method for heavy metal lead in tea leaves
  • Raid detection method for heavy metal lead in tea leaves
  • Raid detection method for heavy metal lead in tea leaves

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Weigh 5.0g of crushed tea dry sample, put it in a polytetrafluoroethylene pressure digestion tank, add 5ml of nitric acid to soak for 1-2h, add 5.0ml of hydrogen peroxide, cover the inner cover, put it in a constant temperature drying oven, 120℃- Keep at 140°C for 3-4 hours, cool naturally in the box to room temperature, transfer the digestive solution into a 25.0ml volumetric flask, wash and dilute to 25.0ml. Concentrate the above-mentioned constant-volume digestion solution to 5.0ml by using a nitrogen blowing instrument with a volume sensing function to obtain sample A to be tested.

[0029] Take different dry samples of pulverized tea leaves, and process them respectively according to the above steps to obtain samples A' and A" to be tested.

Embodiment 2

[0031] Take respectively 5.0ml of the standard lead solution with a concentration of 0.9, 1.0, 1.1, 1.9, 2.0, 2.1 μg / ml, adopt the method of Example 1, obtain 5.0ml of standard sample B, C, D, E through digestion and concentration , F, G.

Embodiment 3

[0033]Add 0.2g PEG-10 stearate to the above-mentioned samples A, B, C, D, E, F, and G respectively, and then add about 3.0ml acetic acid-sodium acetate (acetic acid-sodium acetate buffer with pH 4~6 The solution is prepared by adding about 10ml of glacial acetic acid to about 200g of sodium acetate aqueous solution, and then dilute to 1L). Finally, 2.0 ml of 20 mg / kg xylenol orange solution was added dropwise to the mixed solution to obtain a purple-red chelate compound of lead and xylenol orange, whose color can be distinguished by naked eyes.

[0034] The results are shown in Table 1 below:

[0035] Table 1

[0036]

[0037]

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PUM

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Abstract

The invention discloses a detection method for heavy metal lead in tea leaves; the detection method comprises the following steps of: taking a crushed tea leaf sample, obtaining a clearly and transparently colorless liquid to be measured through resolution and concentration, adding a polyoxyethylene fatty acid ester surface active agent in the colorless liquid to be measured, and then adding a certain amount of buffer solution and controlling pH to be 4-6, and finally adding a xylenol orange solution with the concentration of 20-30mg / kg in a mixed solution A to obtain a sample solution; taking and processing a standard lead solution with the concentration of 0.90-10mumg / ml according to the same method to obtain a standard solution; and then carrying out color comparison on the sample solution and the stand solution. The detection method can be used for conveniently and rapidly detecting the content of the heavy metal lead in the tea leaves.

Description

(1) Technical field [0001] The invention relates to a rapid detection method for heavy metal lead in tea, belonging to the field of rapid detection of food safety. (2) Background technology [0002] Lead is an element not required for human physiology, and it is also one of the heavy metal elements that are cumulatively toxic to the human body. The symptoms of chronic lead poisoning in the human body are: loss of appetite, weight loss, anemia, diarrhea, joint pain, etc. Lead damage is internationally recognized as the number one killer of children's nervous system development. The latest domestic research results show that if the blood lead content in children exceeds 100 micrograms per liter, the intelligence index will drop by 10-20 points. [0003] Lead is widely distributed in nature, and trace amounts of lead are inevitably contained in food. Because lead has a toxic effect on the human body, the national food hygiene standards have clear limits on lead residues in va...

Claims

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Application Information

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IPC IPC(8): G01N21/78
Inventor 林欣大朱诚
Owner CHINA JILIANG UNIV
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