CN103175818A - Method for detecting melamine - Google Patents

Abstract

The invention discloses a method for determining melamine. Add 0.05-5.0mL 0.1-0.5g/L melamine solution, 1.0-2.5mL 4.0× ^10-6 mol/L eosin Y solution, 0.5-1.0mL 2.0×10 ^-4 mol/L neutral red solution and 0.3-1.0 mL pH3.5 Beritan-Robison buffer solution, using the solution without melamine as the reagent blank, dilute to the mark with ultrapure water, and store at 30°C After reacting in a water bath for 30 minutes, measure the fluorescence value F _538nm of the solution containing melamine and the fluorescence value F ₀ of the reagent blank at 538nm on a fluorophotometer with a 1cm quartz cuvette, using 520nm as the excitation wavelength, and calculate the difference ΔF _538nm = F _538nm - F ₀ value. Take 30mL of milk, add 20.0mL of 1% trichloroacetic acid solution and 8.0mL of 2% lead acetate solution, sonicate for 20min; take part of the solution and centrifuge for 10min, take 1mL of supernatant, measure the fluorescence value according to the above method, and calculate the content of melamine in milk . The method of the invention is simple and quick.

Description

A kind of method of measuring melamine

Technical field

The present invention relates to a kind of method of measuring melamine, particularly energy shifts the method for fluorescence spectrum method for measuring melamine.

Background technology

Melamine is a kind of important triazines nitrogen heterocyclic ring organic compound, is commonly used for industrial chemicals, is not useable for food processing or food additives.China is after Sanlu milk powder case in 2008 occurs, and national regulation: in liquid milk (comprising raw milk), milk powder, other prescription emulsifiable powders, the Limited Doses of melamine is 2.5mg/kg, must not sell without exception higher than the product of 2.5mg/kg.Therefore the research new method of setting up content of melamine in a kind of mensuration milk quick, accurate, with low cost has great importance.At present, the assay method of melamine is mainly high performance liquid chromatography, GC-MS(gas chromatography-mass spectrography), Liquid Chromatography-Mass Spectrometry etc.But these method instruments are expensive, are difficult for promoting.Fluorescent spectrometry has that analysis speed is fast, easy and simple to handle, the analysis precision advantages of higher, is widely used in actual analysis.Eosin W or W S-dimethyl diaminophenazine chloride has been applied to protein measuring as energy transfer system, but utilizes this energy transfer system to adopt the fluorescence spectrum method for measuring melamine, there is not yet report.

Summary of the invention

The fluorescent spectrometry that the purpose of this invention is to provide a kind of mensuration melamine that shifts based on eosin W or W S-dimethyl diaminophenazine chloride energy.

Concrete steps are:

(1) add successively the melamine solution of 0.0,0.07,1.0,2.0,3.0,5.0 mL 0.1～0.5g/L in 6 10mL color comparison tubes, then add respectively 1.0～2.5 mL 4.0 * 10 in every color comparison tube ^-6The eosin W or W S of mol/L (EY) solution, 0.5～1.0mL 2.0 * 10 ^-4The Bloomsbury of the dimethyl diaminophenazine chloride of mol/L (NR) solution and 0.3～1.0mL pH3.5 is smooth-Robison (Britton-Robinson, B-R) buffer solution, take the solution that do not add melamine as reagent blank, then with ultrapure water, 6 color comparison tubes are settled to scale, shake up, react 30 min in the water bath with thermostatic control of 30 ℃ after, on fluorophotometer, use the 1cm quartz colorimetric utensil, take 520nm as excitation wavelength, measure respectively at the 538nm place fluorescent value F that contains melamine solution _538nmFluorescent value F with reagent blank ₀, calculate the fluorescent value difference DELTA F _538nm=F _538nm– F ₀Value, its fluorescent value difference DELTA F _538nmρ is linear in 1.4～100mg/L scope with the melamine mass concentration, and equation of linear regression is: Δ F _538nm= 0.7736ρ + 17.33, correlation coefficient r=0.9992 detects and is limited to 1.1mg/L.

(2) get milk 30 mL, adding 20.0 mL mass percent concentrations is that 1% trichloroacetic acid solution and 8.0 mL mass percent concentrations are 2% lead acetate solution, ultrasonic 20 min.Then get part solution in centrifuge tube, centrifugal 10 min get supernatant as liquid to be measured.

(3) get milk liquid 1mL to be measured after step (2) is processed, measure fluorescent value according to the method for step (1), calculate the content of melamine in milk.

The inventive method is easy, quick.

Description of drawings

Fig. 1 is the fluorescence spectrum figure of embodiment of the present invention blank and 20 mg/L melamines (MEL).

Mark a in figure: reagent blank; B:4.0 * 10 ^-6Mol/L EY-2.0 * 10 ^-4Mol/L NR-pH3.5 B-R-20 mg/L MEL.

Embodiment

Embodiment:

(1) add successively the melamine solution of 0.0,0.07,1.0,2.0,3.0,5.0 mL 0.2g/L in 6 10mL color comparison tubes, then add respectively 2.0 mL 4.0 * 10 in every color comparison tube ^-6The eosin W or W S of mol/L (EY) solution, 0.5mL 2.0 * 10 ^-4The Bloomsbury of the dimethyl diaminophenazine chloride of mol/L (NR) solution and 0.5mL pH3.5 is smooth-Robison (Britton-Robinson, B-R) buffer solution, take the solution that do not add melamine as reagent blank, then with ultrapure water, 6 color comparison tubes are settled to scale, shake up, react 30 min in the water bath with thermostatic control of 30 ℃ after, on fluorophotometer, use the 1cm quartz colorimetric utensil, take 520nm as excitation wavelength, measure respectively at wavelength 538nm place the fluorescent value F that contains melamine solution _538nmFluorescent value F with reagent blank ₀, calculate the fluorescent value difference DELTA F _538nm=F _538nm– F ₀Value, its fluorescent value difference DELTA F _538nmρ is linear in 1.4～100mg/L scope with the melamine mass concentration, and equation of linear regression is: Δ F _538nm= 0.7736ρ + 17.33, correlation coefficient r=0.9992 detects and is limited to 1.1mg/L.

(2) measure respectively each 30 mL of Mongolia Ox and Erie's plain chocolate, adding respectively 20.0 mL mass percent concentrations is that 1% trichloroacetic acid solution and 8.0 mL mass percent concentrations are 2% lead acetate solution, ultrasonic 20 min; Then get part solution in centrifuge tube, centrifugal 10 min get supernatant as liquid to be measured.

(3) get Mongolia Ox and each 1mL of Erie's plain chocolate liquid to be measured after step (2) is processed, measure fluorescent value according to step (1) method, calculate the content of melamine in Mongolia Ox, Erie's plain chocolate; Do simultaneously recovery testu, the results are shown in Table 1:

Claims (1)

1. method of measuring melamine is characterized in that concrete steps are:

(1) add successively the melamine solution of 0.0,0.07,1.0,2.0,3.0,5.0 mL 0.1～0.5g/L in 6 10mL color comparison tubes, then add respectively 1.0～2.5 mL 4.0 * 10 in every color comparison tube ^-6The eosin W or W S of mol/L is EY solution, 0.5～1.0mL 2.0 * 10 ^-4The dimethyl diaminophenazine chloride of mol/L be the Bloomsbury of NR solution and 0.3～1.0mL pH3.5 smooth-Robison is B-R buffer solution, take the solution that do not add melamine as reagent blank, then with ultrapure water, 6 color comparison tubes are settled to scale, shake up, after reaction 30 min, on fluorophotometer, use the 1cm quartz colorimetric utensil in the water bath with thermostatic control of 30 ℃, take 520nm as excitation wavelength, measure respectively at the 538nm place fluorescent value F that contains melamine solution _538nmFluorescent value F with reagent blank ₀, calculate the fluorescent value difference DELTA F _538nm=F _538nm– F ₀Value, its fluorescent value difference DELTA F _538nmρ is linear in 1.4～100mg/L scope with the melamine mass concentration, and equation of linear regression is: Δ F _538nm= 0.7736ρ + 17.33, correlation coefficient r=0.9992 detects and is limited to 1.1mg/L;

(2) get milk 30 mL, adding 20.0 mL mass percent concentrations is 1% trichloroacetic acid solution, and 8.0 mL mass percent concentrations are 2% lead acetate solution, ultrasonic 20 min; Then get part solution in centrifuge tube, centrifugal 10 min get supernatant as liquid to be measured;

(3) get milk liquid 1mL to be measured after step (2) is processed, measure fluorescent value according to the method for step (1), calculate the content of melamine in milk.

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