Method for judging illegal cooking oil by relative contents of characteristic compounds

A technology of characteristic compounds and relative content, which is applied in the direction of analysis by nuclear magnetic resonance to achieve the effect of good repeatability and stability

Active Publication Date: 2013-07-17
XIAMEN UNIV
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  • Abstract
  • Description
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Problems solved by technology

This method solves the defect that the detection method in the prior art

Method used

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  • Method for judging illegal cooking oil by relative contents of characteristic compounds

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Embodiment Construction

[0029] The following embodiments will further illustrate the present invention in conjunction with the accompanying drawings.

[0030] Include the following steps:

[0031] 1) Use a liquid nuclear magnetic resonance spectrometer of 300MHz and above for sample testing.

[0032] 2) Put the liquid oil sample into the NMR tube to be tested of the liquid nuclear magnetic resonance spectrometer.

[0033] 3) Add the deuterium band reagent required for the lock field into the NMR tube to be tested; the deuterium band reagent can use 500 μL of deuterated chloroform with more than 99.8% deuterium.

[0034] 4) Directly carry out conventional hydrogen spectrum detection;

[0035] 5) Judgment indicators:

[0036] The judgment indicators and judgment basis are as follows: aldehyde>1.2, aromatic hydrocarbon>1.0, conjugated olefin>0.20, oxide>1.0, free acid>5.5%;

[0037] (1) Aldehyde compounds, acid compounds: through the fingerprint spectrum, it can be observed that the characteristic p...

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Abstract

The invention relates to detection of illegal cooking oil, in particular to a method for judging illegal cooking oil by relative contents of characteristic compounds. The method includes: filling an oil sample into a to-be-detected nuclear magnetism tube of a liquid nuclear magnetic resonance spectrometer, and adding a deuterated reagent needed by field locking; directly performing conventional hydrogen spectrum detection; judging indexes of aldehyde>1.2, aromatic hydrocarbon>1.0, conjugated alkene>0.20, oxide>1.0 and free acid>5.5%; and calculating the relative contents of the aldehyde, the aromatic hydrocarbon, the conjugated alkene and the oxide and the mole percent of the free acid accounting for total fatty acids, and if the relative contents exceed limit values, judging the oil sample as the illegal cooking oil. The method is quick and simple. Results can be obtained only 5 min after a sample is taken. The sample is undamaged, and pretreatment is not needed. Data collection can be completed on any high-field nuclear magnetic resonance spectrometers. The results are exported by data analysis. Repeatability and stability of the whole data collection and analysis are good, and large difference due to different used instruments is avoided.

Description

technical field [0001] The invention relates to the detection of waste oil, in particular to a method for judging the waste oil through the relative content of characteristic compounds. Background technique [0002] At present, there is no uniform standard for the detection of waste oil in China. Existing technical means include thin-layer chromatography, fluorescence spectroscopy, air chromatography-mass spectrometry (GC-MS), conductivity, gas chromatography (GC), atomic absorption spectroscopy, and plasma-coupled mass spectrometry (ICP-MS). [0003] In the current national standard GB2716-2005 "Hygienic Standards for Edible Vegetable Oils", the physical and chemical testing indicators of edible vegetable oils include acid value, peroxide value, solvent residue in leaching oil, free phenol (cottonseed oil), total arsenic, lead, aflatoxin, Benzopyrene and pesticide residues have a total of 9 indicators, and different detection indicators are stipulated for vegetable crude o...

Claims

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Application Information

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IPC IPC(8): G01N24/08
Inventor 黄慧英
Owner XIAMEN UNIV
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