CN102749325B - Application of 3,3',5,5'-tetramethyl benzidine in detecting benzoyl peroxide added to flour - Google Patents

Abstract

The invention discloses new application of 3,3',5,5'-tetramethyl benzidine, wherein 3,3',5,5'-tetramethyl benzidine can be used for qualitatively detecting or quantitatively detecting benzoyl peroxide added to flour. 3,3',5,5'-tetramethyl benzidine contacts with benzoyl peroxide and reacts quickly; the generated product has obvious blue color, and the reaction sensitivity is high; and at least 4.0mg/kg of benzoyl peroxide in the flour can be detected. When in quantitative detection, the sample processing process is simple, the color reaction can be realized without complicated steps, the detection time is saved, and the detection result is stable and reliable; and moreover, 3,3',5,5'-tetramethyl benzidine is nonhazardous to human body and harmless to environment.

Description

3,3', 5,5'-tetramethyl benzidine is for detection of the benzoyl peroxide being added in flour

Technical field

The invention belongs to food additives detection field, be specifically related to the detection of benzoyl peroxide.

Background technology

Benzoyl peroxide (C ₁₄h ₁₀o ₄represent with BPO below) be that the one that Flour production manufacture field is conventional brightens adjuvant, excessive benzoyl peroxide can cause the considerable damage of the nutritional labelings such as beta carotene in food, vitamin A, Cobastab, vitamin E, and the edible benzoic wheat flour that contains excessive benzoyl peroxide hydrolysis generation is very harmful to liver, and easily cause various diseases, occur the symptoms such as bleeding gums, cutaneous purpura, therefore each state has all specified its limit standard.The maximum use amount of China's regulation benzoyl peroxide in " the food additives food sanitation standard " of revision in 1997 is 60 mg/kg, and the Ministry of Public Health required to completely forbid and in flour, adds benzoyl peroxide in 2011.

At present there are two kinds of chromatography and spectrophotometric method for the detection technique of benzoyl peroxide.Chromatography mainly contains vapor-phase chromatography, high performance liquid chromatography and capillary electrophoresis.These methods need first BPO to be reduced to benzoic acid, then rely on huge or expensive exact instrument to complete.Spectrophotometric method comprises iodimetric titration, iron powder reducing method, oxammonium hydrochloride reducing process, the sample pre-treatments complex steps of these methods, the experimental technique personnel that the running time is long and needs are skilled.Also have report to adopt N, N, N', N'-tetramethyl-para-phenylene diamine, N-ethyl-2-naphthylamines and N, the dissimilar developers such as N-dimethyl-p-phenylenediamine make BPO be converted into coloring matter, and these chromogenic reactions not only heat reaction system with water bath with thermostatic control, and need to use catalyzer.In addition,, because aniline category matter has strong carcinogenic teratogenesis, limited the application of these methods.The method of said determination BPO particularly has certain limitation in conventional analysis in practical application.Therefore, find new highly sensitive, selectivity set up well and on this basis easy and simple to handle, sensitive reliable, can meet that BPO routine analysis requires, green new method is very necessary.

3,3', 5,5'-tetramethyl benzidine (3,3', 5,5'-tetramethylbenzidine, below represents with TMB) be a kind of original reagent of going back of new type of safe, progressively replace the benzidine derivative of strong carcinogen biphenylamine and other carcinogenicity, be applied to clinical assay, forensic medical examination, criminal detection and environmental monitoring field, up to now, this reagent there is not yet report in the application of food processing field.

Summary of the invention

The object of this invention is to provide a kind of 3,3', the new purposes of 5,5'-tetramethyl benzidine.

3,3', the purposes of 5,5'-tetramethyl benzidine, for qualitative detection or the quantitative benzoyl peroxide that is added on flour that detects.

Further, described qualitative detection is to drip 3,3' in flour, and the ethanolic solution of 5,5'-tetramethyl benzidine, mixes, and is judged whether the content of benzoyl peroxide in flour exceedes 4.0 mg/kg by the variation of flour color:

(1) flour color becomes the blue content that represents benzoyl peroxide in flour and exceedes 4.0 mg/kg;

(2) in the unchanged expression flour of flour color, do not contain benzoyl peroxide or Determination of benzoyl peroxide in wheat lower than 4. 0 mg/kg.

Further, described quantitative detection is to carry out according to following steps:

(1), by acetone washing, centrifugal treating for flour 2～3 times, merge the supernatant liquor of centrifugal gained;

(2) step (1) gained clear liquid dries up with nitrogen, obtains white solid;

(3) in white solid, add 3,3', 5,5'-tetramethyl benzidine ethanolic solution, then add the sodium dihydrogen phosphate buffer of pH=4.0, constant volume, measures the absorbance of solution in 652 nm places;

(4) with the white solid of benzoyl peroxide standard items alternative steps (3), draw concentration-absorbance typical curve;

(5) can be calculated the content of benzoyl peroxide in flour by the absorbance of step (3) and concentration-absorbance typical curve of step (4).

The calculating of Determination of benzoyl peroxide in wheat:

Wherein, W is the content (mg/kg) of benzoyl peroxide in flour; C is the concentration (mg/L) of benzoyl peroxide in step (3) solution; V is the constant volume (L) of step (3) solution; The quality (kg) that m is taken flour.

Further, the described washing of step (1) is with vortex oscillator, flour to be scattered in acetone, more ultrasonic processing.

3,3', 5, rapidly reaction after 5'-tetramethyl benzidine contacts with benzoyl peroxide, the product of generation has obvious blueness, reaction highly sensitive, utilize the feature of this reaction to realize the detection of benzoyl peroxide, the minimum benzoyl peroxide that detects 4.0 mg/kg in flour.Qualitative detection goes out benzoyl peroxide simply rapidly; While quantitatively detection, sample preparation is simple, without realizing chromogenic reaction through complicated loaded down with trivial details step, save detection time, testing result is reliable and stable, the relative standard deviation of three revision tests is all less than 3.55%, and 3,3', 5,5'-tetramethyl benzidine is to human body nonhazardous, to environment without harm.

Brief description of the drawings

Fig. 1 is 3,3', the benzoyl peroxide chromogenic reaction of 5,5'-tetramethyl benzidine to variable concentrations.

Fig. 2 is 3,3', the benzoyl peroxide in 5,5'-tetramethyl benzidine qualitative detection flour.

Embodiment

Below by drawings and Examples, the present invention will be further described.

Embodiment 1

Take 4 parts of commercially available flour solids and be placed in respectively centrifuge tube, every part of 0.50 g, then every part adds respectively the BPO standard items of 0.0,10.0,20.0 and 40.0 μ g, add again 2 mL acetone, with vortex oscillator (its woods Bel, QL-901) after flour is mixed with acetone, ultrasonic processing 5 minutes, after high speed centrifugation, take out supernatant liquor, in the flour of centrifugal gained, add again 1 mL acetone, ultrasonic, centrifugal, repeat after twice, merge centrifugal obtained supernatant liquor, under normal temperature, with nitrogen, clear liquid is dried up, obtain white solid.Add the ethanolic solution of 15 μ L 20 mmol/L TMB to gained white solid, then add immediately the sodium dihydrogen phosphate buffer of 20 mmol/L pH=4.0, be settled to 3 mL, obtain blue solution.After insoluble substance being filtered with the miillpore filter of 0.45 μ m, with spectrophotometer, in the absorbance of 652 nm places mensuration solution, every part of replicate determination three times, gets average, according to the typical curve of concentration-absorbance, draws the concentration of BPO.

Draw concentration-absorbance typical curve: take respectively 0.0,2.0,8.0,14.0,24.0,36.0 and 48 .0 μ g BPO standard items, every part of BPO standard items add 15 μ L 20 mmol/L TMB ethanolic solutions, then add immediately the sodium dihydrogen phosphate buffer of 20 mmol/L pH=4.0, be settled to 3 mL, obtain series standard solution, in the absorbance of 652 nm place bioassay standard solution, draw concentration-absorbance typical curve with spectrophotometer.

The calculating of Determination of benzoyl peroxide in wheat in flour:

Wherein, W is the content (mg/kg) of benzoyl peroxide in flour; C is the concentration (mg/L) of benzoyl peroxide in step (3) solution; V is the constant volume (L) of step (3) solution; The quality (kg) that m is taken flour.

Experimental result:

。

Embodiment 2:

Take the commercially available flour of 1 g and be divided into two parts, be placed on clean glass plate, in portion, add wherein 60 μ g BPO solids, mix.Then to dripping respectively 15 μ L 20 mmol/L TMB ethanolic solutions in these two parts of flour, mixing immediately, do not add the flour of BPO still to present white (Fig. 2 left side), the flour aobvious blue (Fig. 2 right side) that has added BPO, progressively reduces BPO content, show that minimum detectability is 4.0 mg/kg.

Claims (1)

1.3,3', the purposes of 5,5'-tetramethyl benzidine, is characterized in that: for qualitative detection or the quantitative benzoyl peroxide that is added on flour that detects;

Described qualitative detection is to drip 3,3' in flour, and the ethanolic solution of 5,5'-tetramethyl benzidine, mixes, and is judged whether the content of benzoyl peroxide in flour exceedes 4.0 mg/kg by the variation of flour color:

(1) flour color becomes the blue content that represents benzoyl peroxide in flour and exceedes 4.0 mg/kg;

(2) in the unchanged expression flour of flour color, do not contain benzoyl peroxide or Determination of benzoyl peroxide in wheat lower than 4.0 mg/kg;

Described quantitative detection is to carry out according to following steps:

(1), by acetone washing, centrifugal treating for flour 2～3 times, merge the supernatant liquor of centrifugal gained;

(2) step (1) gained clear liquid dries up with nitrogen, obtains white solid;

(3) in white solid, add 3,3', the ethanolic solution of 5,5'-tetramethyl benzidine, then add the sodium dihydrogen phosphate buffer of pH=4.0, constant volume, utilizes spectrophotometer to measure the absorbance of solution in 652 nm places;

(4) with the white solid of benzoyl peroxide standard items alternative steps (3), draw concentration-absorbance typical curve;

(5) can be calculated the content of benzoyl peroxide in flour by the absorbance of step (3) and concentration-absorbance typical curve of step (4).