Method for determining melamine content by using ultraviolet spectroscopy

A melamine and ultraviolet spectrum technology, applied in the measurement of color/spectral characteristics, etc., can solve the problems of complicated operation, low detection sensitivity, complex sample pretreatment, etc., and achieve the effect of accurate and effective measurement and simple operation.

Inactive Publication Date: 2012-10-24
NINGBO INST OF TECH ZHEJIANG UNIV ZHEJIANG
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Problems solved by technology

At present, there are GC-MS, HPLC, LC-MS, capillary electrokinetic chromatography, etc. for the determination of melamine. Some of these methods require more complicated sample pretreatment, cumbersome operation, and some methods have relatively low detection sensitivity (the usual detection sensitivity between 10.9μg / kg~0.25mg / kg), it is difficult to meet the daily rapid detection

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  • Method for determining melamine content by using ultraviolet spectroscopy
  • Method for determining melamine content by using ultraviolet spectroscopy

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Establishment of the method for the interaction between melamine and DNA

[0020] (1) Use Tris (0.05mol / L)-HCl buffer solution with pH = 7.00 to prepare MM solution, DNA solution, and DNA-MM mixed solution respectively, shake well, let it stand for 20 minutes, and use the reagent blank as a reference to scan the electron absorption spectrum (i.e. ultraviolet spectrum);

[0021] (2) In a 1cm cuvette, add 3.00mL DNA solution, scan the electronic absorption spectrum or measure the absorbance by titration, add MM 10μL each time, and the volume effect can be ignored.

[0022] (3) Measure the electronic spectrum of DNA before and after adding MM to Tris(0.05mol / L)-HCl buffer solution with pH=7.00, see attached figure 1 . After the MM solution was added dropwise to the DNA solution, a small red shift (~2nm) and a color reduction effect (absorbance A decreased by ~0.05, ~10%) were observed at the position of the characteristic absorption peak of DNA at ~260nm, and the DNA - ...

Embodiment 2

[0025] Establishment of method for determination of melamine by ultraviolet spectrometry

[0026] In 3.00mL the concentration is 6.4×10 -5 A series of melamine solutions were added to the mol / L DNA solution so that the concentration of melamine was 0.084~1.68 μg / L. The absorbance of the DNA solution at 260 nm was measured before and after adding melamine. The data are listed in Table 1. Take the concentration of melamine as the abscissa, and take the difference (ΔA) between the absorbance of DNA without adding melamine and the absorbance of a DNA solution with a certain concentration of melamine as the ordinate to establish a working curve. The results are listed in the attached figure 2 . From the results, it can be seen that ΔA and the concentration of melamine conform to the Lambert-Beer law, showing a good linear relationship in the concentration range of 0.084~1.68μg / L; according to the definition of the international IUPCA: the detection limit is C DL =3S B / k, wh...

Embodiment 3

[0031] Detection of Melamine Residues in Feed Samples

[0032]Accurately weigh 5g of feed into a 50mL centrifuge tube. Add 20 mL of dimethyl sulfoxide (DMSO), shake for 1 hour, centrifuge to get 1 mL of supernatant, and prepare and dilute to 10 mL with Tris (0.05 mol / L)-HCl buffer solution for later use. Take 50.00μL of the above solution in 3.00mL DNA solution (concentration is 6.4×10 -5 mol / L DNA solution), shake well, stand still for 20 minutes, and measure its absorbance at 260nm. According to the established standard curve, calculate the residual content of melamine in the sample. The melamine residues in the 5 kinds of feed samples measured and the methods for the determination of melamine in the feed of the Ministry of Agriculture (NY1372-2007) (the minimum quantification limit of the HPLC method in this standard is 2.0mg / kg, and the minimum quantification limit of the GC-MS method is 0.05mg / kg) are listed in Table 2.

[0033] Table 2 Determination results of melami...

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Abstract

The invention discloses a method for determining a melamine content by using ultraviolet spectroscopy. The method comprises steps of preparing a Tris-HCl buffer solution with a pH value of 4 to 10; preparing a melamine solution of 0 to 10 [mu]g / L, a DNA solution of 1.0 x 10<-5> to 1.5 x 10<-4> mol / L and a mixing solution of the melamine and DNA by using the Tris-HCl buffer solution, and determining absorbance of each solution using a blank reagent as a reference; establishing a working curve using a melamine concentration as an abscissa, and using differences between the DNA absorbance and the absorbance of the mixing solution of the melamine and the DNA as an ordinate; and adding a to-be-measured melamine liquid into the DNA solution, determining the absorbance, calculating the melamine concentration in accordance with the working curve, and converting the concentration into a corresponding melamine content in the to-be-measured liquid. The method employs an ultraviolet spectrum detection technology established on the basis of interactions of the melamine and deoxyribonucleic acid, and is accurate, simple, convenient and repeatable.

Description

technical field [0001] The invention relates to an analytical method for measuring melamine by a spectroscopic method. In particular, it is a simple, fast and accurate method for determining the content of melamine by ultraviolet spectroscopy based on the interaction between melamine and deoxyribonucleic acid (DNA). Background technique [0002] Melamine (Melamine, hereinafter referred to as MM, molecular formula C 6 h 6 N 6 It is a widely used chemical raw material with a nitrogen content of 66.6%. Some unscrupulous companies add it to milk, dairy products, and feed, resulting in falsely high crude protein, which not only has adverse effects on dairy products, aquaculture and other industries, but also poses a serious threat to human health. Although the shocking "melamine" incident in September 2008 was highly valued by the relevant state departments, the emergency response work has come to an end, but the research on the detection technology of melamine has always bee...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/33
Inventor 沈昊宇徐宁逸郑惠敏柳杨青林峰
Owner NINGBO INST OF TECH ZHEJIANG UNIV ZHEJIANG
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