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Method for determining dithiocarbamate residues in tea leaves by means of headspace-gas chromatography-mass spectrometry

A dithioamino and gas chromatography technology is applied in the field of determination of dithiocarbamate residues in tea leaves by headspace-gas chromatography-mass spectrometry, which can solve the problem of large matrix interference, high detection cost, damage to automatic samplers, etc. question

Inactive Publication Date: 2019-12-20
PUER COMPREHENSIVE TECHN TESTING CENT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The national standard GB 2763 stipulates that dithiocarbamate residues are determined by CS 2 To express, domestic standards currently use headspace-gas chromatography and liquid chromatography-mass spectrometry / mass spectrometry to determine the content of dithiocarbamate. For the determination of dithiocarbamate in tea, due to Its matrix has a lot of interference. When using national standards, there are the following problems: headspace-gas chromatography has a high detection limit, damages the autosampler, and is prone to qualitative and quantitative errors. However, liquid chromatography-mass spectrometry / mass spectrometry is complicated in pretreatment and detection high cost

Method used

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  • Method for determining dithiocarbamate residues in tea leaves by means of headspace-gas chromatography-mass spectrometry
  • Method for determining dithiocarbamate residues in tea leaves by means of headspace-gas chromatography-mass spectrometry
  • Method for determining dithiocarbamate residues in tea leaves by means of headspace-gas chromatography-mass spectrometry

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0066] Prepare standard solutions:

[0067] Carbon disulfide standard solution: Weigh 0.0500g carbon disulfide (purity ≥ 99%) in a 50mL volumetric flask filled with a small amount of n-heptane, use n-heptane to make up volume, prepare a carbon disulfide solution with a concentration of 1.0000mg / mL, and use this solution with Dilute the intermediate standard solution with n-heptane to a concentration of 1 μg / mL, and then gradually dilute to a concentration of 0.01 μg / mL, 0.02 μg / mL, 0.04 μg / mL, 0.10 μg / mL, 0.20 μg / mL and 0.5 μg / mL Carbon disulfide standard solution, placed in a refrigerator at 4°C for standby;

[0068] Mancozeb standard solution: Weigh a certain amount of mancozeb into a volumetric flask, dilute to volume with 5% EDTA aqueous solution, prepare a dithiocarbamate intermediate standard solution with a concentration of 10 μg / mL, and then Diluted step by step to a concentration of 0.04μg / mL, 0.1μg / mL, 0.2μg / mL, 0.4μg / mL, 1.0μg / mL and 2.0μg / mL mancozeb standard solu...

Embodiment 2

[0115] Test the concentration (in carbon disulfide) of the dithiocarbamate in green tea according to the test method in embodiment 1, do not contain dithiocarbamate in green tea, test sample addition standard recovery and relative standard deviation, The results are shown in Table 1.

Embodiment 3

[0117] Test the concentration of the dithiocarbamate in Pu'er cooked tea according to the test method in Example 1 (calculated as carbon disulfide), do not contain dithiocarbamate in Pu'er cooked tea, and test sample addition recovery rate and the relative standard deviation, the results are shown in Table 1.

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Abstract

The invention provides a method for determining dithiocarbamate residues in tea leaves by means of headspace-gas chromatography-mass spectrometry. The method belongs to the technical field of chemicalanalysis, and comprises the steps of: mixing the tea leaves, a stannous chloride-hydrochloric acid solution and n-heptane, then sealing the mixture, carrying out dithiocarbamate decomposition and carbon disulfide absorption, then centrifuging the mixture, taking an upper-layer solution, putting the upper-layer solution into a headspace bottle, and carrying out headspace-gas chromatography-mass spectrometry determination; and calculating a residual amount of the dithiocarbamate in the tea leaves according to the result of headspace-gas chromatography-mass spectrometry determination. The methodreduces the corrosion of direct determination to a headspace sample injector through transferring carbon disulfide into n-heptane and then carrying out headspace-gas chromatography-mass spectrometrydetermination, can precisely determine the residual amount of dithiocarbamate in the tea leaves and reduces the interference of a tea leaf matrix.

Description

technical field [0001] The invention relates to the technical field of chemical analysis, in particular to a method for determining residual dithiocarbamate in tea leaves by headspace-gas chromatography-mass spectrometry. Background technique [0002] Dithiocarbamate is a protective fungicide, mainly used in the control of downy mildew, spot disease, head blight, etc. . Dithiocarbamate is insoluble in water, insoluble in most organic solvents, unstable to light, heat, and humidity, and easily decomposes into CS in acidic environments 2 . At present, there are mainly two kinds of standard methods for the determination of dithiocarbamate residues. One is to measure the content of carbon disulfide produced by gas chromatography (GC), and the other is to use liquid chromatography-mass spectrometry / mass spectrometry (HPLC). -MS-MS) to determine the content of the product after methyl derivatization. The national standard GB 2763 stipulates that dithiocarbamate residues are de...

Claims

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Application Information

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IPC IPC(8): G01N30/02G01N30/16
CPCG01N30/02G01N30/16G01N2030/047G01N2030/062
Inventor 满红平吕生车涛毛静春
Owner PUER COMPREHENSIVE TECHN TESTING CENT
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