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Determination of amount of residual dithiocarbamate bactericide in grain through gas chromatography method

A technology of dithiocarbamate and gas chromatography, applied in measuring devices, instruments, scientific instruments, etc., to overcome instability, eliminate interference, and reduce damage

Inactive Publication Date: 2015-04-15
SUZHOU PUNI TEST TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] At present, there are many reports on the residual analysis methods of dithiocarbamate fungicides in vegetables and fruits: Determination of decomposition products includes carbon disulfide spectrophotometry, headspace gas chromatography-flame photometry (sulfur) detection method, top Air chromatography-electron capture detection, determination of methylation products include liquid chromatography and liquid chromatography-mass spectrometry, but there are few studies on the residues of dithiocarbamate fungicides in grain

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  • Determination of amount of residual dithiocarbamate bactericide in grain through gas chromatography method
  • Determination of amount of residual dithiocarbamate bactericide in grain through gas chromatography method
  • Determination of amount of residual dithiocarbamate bactericide in grain through gas chromatography method

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Experimental program
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Embodiment 2

[0036] The selection of embodiment 2 sampling mode

[0037] Headspace sampling will cause the problem of poor sampling repeatability. Mancozeb decomposes into carbon disulfide under acidic conditions. Carbon disulfide gas will contain a large amount of HCl gas, which is very acidic and seriously damages the chromatographic column and the ECD detector. Therefore, the isooctane solution, which is relatively non-volatile and highly soluble to carbon disulfide, is used to absorb the carbon disulfide produced by the decomposition of mancozeb. Isooctane has no solubility to HCl gas, and the measured absorption pH is neutral, avoiding the impact of acidic substances on the chromatographic column. and detector damage.

Embodiment 3

[0038] The selection of embodiment 3 instruments

[0039] Compared with the ECD detector, the FPD detector has good selectivity, which eliminates the large interference factors of the ECD detector impurity; compared with the GC-MS, because the peak time of carbon disulfide is earlier, the solvent delay cannot be carried out, which seriously affects the GC-MS. MS, so choose FPD detector with sulfur filter.

Embodiment 4

[0040] Embodiment 4 method detection limit and precision

[0041] Add the diluted standard to the sample, add stannous chloride-hydrochloric acid for hydrolysis, absorb in isooctane, centrifuge, and measure with isooctane solution gas chromatography. The experiment shows that when 0.2 μg of standard is added, the response of the target The signal is 2-3 times of the noise signal; that is, the minimum detection amount of this method is 0.2 μg, and the detection limit of this method is calculated according to the following formula

[0042] MDL=C / m

[0043] In the formula: C is the minimum detection amount, and m is the weighing amount.

[0044] Calculated according to the sample mass of 5 g and constant volume of 5 mL, the detection limit of this method is 0.04 mg / kg.

[0045] Weigh 6 parts of the same sample, each 5g±0.01g, measure according to the above-mentioned experimental method, the results are shown in Table 1. It can be seen from Table 1 that the relative standard de...

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Abstract

The present invention discloses a method for determining the amount of residual dithiocarbamate bactericide in grain through a gas chromatography method. The determination method comprises that: a sample reacts with a reducing acid solution in a closed container, dithiocarbamate is decomposed, carbon disulfide is quantitatively released and is absorbed with an organic solvent, the organic layer is taken and is subjected to chromatography analysis by using a gas chromatograph (with FPD-S filter), qualitation is performed on the target substance according to the chromatography peak retention time, and quantitation is performed through an external standard method. According to the present invention, the organic solvent is adopted to absorb the carbon disulfide generated from acidification decomposition of the dithiocarbamate bactericide, and the analysis through the gas chromatograph is performed, such that the instability of the headspace sample injection is overcome, the damage of the acid condition on the column is overcome, the interference can further be eliminated, and the qualitative and quantitative analysis can be well performed; and the minimum detection limit of the method is 0.04 mg / kg.

Description

technical field [0001] The invention belongs to the technical field of food detection, and in particular relates to the determination of the residual amount of dithiocarbamate fungicides in food by gas chromatography, and more specifically relates to a gas phase-FPD with a sulfur filter Method for the determination of the residual amount of dithiocarbamate fungicides in grain by detector. Background technique [0002] The birth of dithiocarbamate fungicides (Dysen fungicides) in the 1940s made fungicides take a major step from inorganic to organic. Dithiocarbamate fungicides are organosulfur fungicides derived from the parent compound dithiocarbamic acid. They are protective fungicides and can form a dense protective film on the surface of crops after spraying. Inhibit the germination and invasion of germs, so as to achieve the purpose of disease prevention. At the same time, Ammonium, Zinc, Mancozeb, and Thiamex can also provide plants with trace elements such as nitrogen...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/02
Inventor 宋薇
Owner SUZHOU PUNI TEST TECH CO LTD
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