CN103091418B - Method for detecting plasticizing agent - Google Patents

Abstract

The invention discloses a method for detecting a plasticizing agent in milk and milk products. The method comprises the following steps of: (1) preparing a standard solution, detecting by utilizing a gas chromatography-mass spectrometry to obtain retention time and a standard curve; (2) weighing raw milk or milk products and cyclohexane, swirling and mixing for 2-5 minutes, then adding sodium chloride and aluminum oxide, and swirling and shaking for 2-5 minutes, centrifuging at a rotary speed of 4000r/min for 5-10 minutes and taking liquid supernatant to detect; and (3) comparing a detected result obtained by the step (2) with the standard curve obtained in the step (1), and calculating and determining the content of the plasticizing agent. With the adoption of the method disclosed by the invention, a pre-treatment process is simple, a detection speed is fast and the precision of the detected result is high.

Description

A kind of method that detects plasticiser

Technical field

The present invention relates to a kind of chromatographic detection method of plasticiser, particularly the gas chromatography-mass spectrum detection method of plasticiser in a kind of dairy products.

Background technology

Plasticiser, is industrial widely used macromolecular material auxiliary agent, adds this material in plastic processing, can make its pliability strengthen.Lawless person is added in the middle of food, replaces emulsifying agent, and thickening agent uses, and serious harm is healthy to the people common people's.

Plasticiser is the plastifier that can be used for packaging material for food, is not raw-food material, neither food additives, forbid artificially to add in food, food additives.In food containers, packaging material for food, use phthalate material, kind, scope and the Special migration or the residual quantity that should strict implement " food containers, wrappage use hygienic standard with adjuvant " (GB9685-2008) stipulate.According to (defend and do supervision letter (2011) No. 551) regulation, grease based food and infant food, the phthalic acid two (α-ethylhexyl ester) in food, food additives (DE-HP), diisononyl phthalate (DINP) and n-butyl phthalate (DBP) maximum residue limit be respectively 1.5mg/kg, 9.0mg/kg and 0.3mg/kg.

The method that existing GB detects plasticiser in food is national standard method GB/T21911-2008 " mensuration of Phthalic Acid Esters in Food " (hereinafter to be referred as GB/T21911-2008).The product of dairy industry is mostly for containing grease dairy produce, testing process need to be removed to sample the pre-treatment of degrease, concrete grammar is to get the dairy products sample mixing, with ethyl acetate: cyclohexane (volume ratio 1:1) mixed liquor extracts, filter, purify, concentrate through gel permeation chromatography device, enter gas chromatograph-mass spectrometer (GCMS) (GC-MS) analyzing and testing.

Processing sample to be tested with gel permeation chromatographic column, is a kind of method of utilizing the different-diameter of molecule to be isolated out.In gel permeation chromatographic column, can there is the through hole (less) in interparticle gap (larger) and particle for the current path of molecule.When dairy products sample flow of solution is during through gel permeation chromatographic column, larger fat molecule, protein molecule is excluded outside the aperture of particle, can only pass through from interparticle gap, and speed is very fast; And less plasticiser molecule can enter the aperture in particle, it is much slow that the speed of passing through is wanted.Through the chromatographic column of certain length, molecule is according to relative molecular mass by separately, and fat molecule that relative molecular mass is large, protein molecule be above (being that the drip washing time is short), plasticiser molecule (being that the drip washing time is long) in the back that relative molecular mass is little.Determine after instrument and experiment condition, it is relevant with its molecular weight that the pouring of solute goes out the time, collects special time period, collects the effluent of 5.5min～16.5min in GB/T21911-2008, obtain the plasticiser molecule enrichment that will detect and detect liquid, then carry out gas chromatography-mass spectrum detection.

Gel permeation chromatography, can be used for separation and the evaluation of small-molecule substance, also can be used to the different macromolecule homolog of analytical chemistry character same molecular volume.Gel permeation chromatography purification plant price higher (market price is in 300,000 left and right), general dairy enterprises is used less, and is not equipped with this device.While test according to GB/T21911-2008, hardware condition restriction, cannot complete the sampling check of enterprises plasticiser.And gel permeation purification device uses operation more complicated, needs special messenger assistant director to test, and is unfavorable for drawing fast testing result.

Summary of the invention

The object of the invention is to overcome in prior art, because need to use the different chromatographic system of two covers (gel permeation chromatography and gas chromatography), some enterprise causing is because objective condition, and the deficiency that temporarily cannot carry out plasticiser detection provides the method for a kind of fast detecting Ruzhong plasticiser.

In order to realize foregoing invention object, the invention provides following technical scheme:

A method that detects plasticiser in dairy products, comprises the following steps:

(1) preparation standard solution, utilizes gas chromatograph-mass spectrometer (GCMS) to detect it, obtains retention time, and generates typical curve corresponding between concentration and response.

(2) sample thief carries out pre-service, obtains machine testing sample, utilizes described gas chromatograph-mass spectrometer (GCMS) under the condition identical with step (1), it to be detected, and obtains retention time and response.

(3) retention time obtaining in the sample retention time obtaining in step (2) and response and step (1) and described typical curve are compared, the content of plasticizing agent in calculative determination sample.

Pre-service in described step (b) comprises, measures dairy products and cyclohexane, is placed in centrifuge tube mesoscale eddies and mixes 2～5min; Then add sodium chloride and aluminium oxide, vortex vibration 3～5min, with the centrifugal 5～10min of 4000r/min, gets supernatant and carries out upper machine processing.

Further preferred, the pre-service in described step (b) comprises, gets 2mL plain chocolate and 5mL cyclohexane, is placed in centrifuge tube mesoscale eddies and mixes 2～5min; Then in centrifuge tube, add 0.3g sodium chloride and 0.1g aluminium oxide, by centrifuge tube vortex vibration 3min, with the centrifugal 5min of 4000r/min rotating speed, get supernatant and carry out upper machine processing.

Further, in GC-MS testing process, testing conditions:

Chromatographic condition: chromatographic column, HP-5MS quartz capillary, 30m × 0.25mm(i.d.), 0.25 μ m; Injector temperature, 280 ℃; Heating schedule, 60 ℃ of initial column temperatures, keep 1min, are warming up to 220 ℃ with 20 ℃/min, keep 1min, then are warming up to 280 ℃ with 5 ℃/min, keep 4min; Carrier gas, nitrogen (purity >=99.999%); Flow velocity 1mL/min; Input mode, Splitless injecting samples; Sample size, 1 μ l;

Mass spectrum condition: chromatogram and mass spectrometer interface temperature: 280 ℃; Ionization mode, electron bombardment ionization source (EI); Monitoring mode, selects ion scan pattern (SIM); Ionizing energy, 70eV; Solvent delay, 5min.

In the present invention, in sample to be checked, adding cyclohexane reagent, is because plasticiser is soluble in cyclohexane, utilizes the fully plasticiser composition in lixiviate milk of cyclohexane reagent.Fat, protein content in milk is higher simultaneously, utilizes sodium chloride to change the ion concentration in liquid, reduces the solubleness of the materials such as protein, and protein is separated out; Aluminium oxide has good absorption, settlement action to macromolecular substances, can adsorb the material such as fat, protein of removing in milk, thereby plasticiser composition is dissolved in cyclohexane, by centrifuging, then get its supernatant, obtain containing the less extract of its impurity.Finally complete the detection of Ruzhong plasticiser by gas chromatograph-mass spectrometer (GCMS).Can reach the extraction of gel permeation chromatography device to plasticiser in raw milk or dairy products and the same texts of enrichment by above experimental procedure.The detection method recovery of the present invention, between 92%～120%, has the advantages such as quick, accurate, is specially adapted to the detection of plasticiser in milk and milk products.

The inventive method is applicable to the detection of the plasticiser in raw milk and liquid dairy products.

Compared with prior art, beneficial effect of the present invention:

Compared with prior art GB/T21911-2008 method, in pretreatment process, without using gel permeation chromatography device, effectively reduce testing cost, accelerate detection speed.And having reached national standard method uses gel permeation chromatography device to separate the same texts of concentrated plasticiser.A kind of method of simple and feasible detection plasticiser is provided for not being equipped with the food enterprise of gel permeation chromatography device.

In operating process, without using gel permeation chromatography device, saved detection funds, processing procedure is easier, and detection speed is faster, and testing result degree of accuracy is high.

Accompanying drawing explanation:

Fig. 1 plasticiser standard items collection of illustrative plates

The spectrogram of the own ester of Fig. 2 selective scanning dibutyl phthalate and phthalic acid two (2-ethyl)

The typical curve (20ppb ~ 2ppm R=1) of Fig. 3 dibutyl phthalate

The typical curve (20ppb ~ 2ppm R=0.999) of the own ester of Fig. 4 phthalic acid two (2-ethyl)

Fig. 5 sample 1 detects the collection of illustrative plates of DBP and DEHP

Fig. 6 sample 2 detects the collection of illustrative plates of DBP and DEHP

Fig. 7 sample 3 detects the collection of illustrative plates of DBP and DEHP

Fig. 8 sample 4 detects the collection of illustrative plates of DBP and DEHP

Embodiment

Below in conjunction with test example and embodiment, the present invention is described in further detail.But this should be interpreted as to the scope of the above-mentioned theme of the present invention only limits to following embodiment, all technology realizing based on content of the present invention all belong to scope of the present invention.

1) reagent and instrument

Phthalic ester standard reserving solution (1000mg/kg); Normal hexane (chromatographically pure), it is pure that all the other reagent are analysis

Gas chromatograph-mass spectrometer (GCMS), electronic balance (being accurate to 0.1 milligram), vortex oscillator, supercentrifuge, glassware is commonly used (after glassware used is clean, with double distilled water drip washing three times in laboratory, acetone soaks 1 hour, toasts 2 hours at 200 ℃, is cooled to room temperature for subsequent use.）

2) testing conditions

201) chromatographic condition

Chromatographic column: HP-5MS quartz capillary [30m × 0.25mm(internal diameter) × 0.25um]

Injector temperature: 280 ℃;

Heating schedule: 60 ℃ of initial column temperatures, keep 1min, be warming up to 220 ℃ with 20 ℃/min, keep 1min, then be warming up to 280 ℃ with 5 ℃/min, keep 4min.

Carrier gas: nitrogen (purity >=99.999%), flow velocity 1ml/min;

Input mode: Splitless injecting samples;

Sample size: 1 μ l.

202) mass spectrum condition

Chromatogram and mass spectrometer interface temperature: 280 ℃;

Ionization mode: electron bombardment ionization source (EI);

Monitoring mode: select ion scan pattern (SIM);

Ionizing energy: 70eV;

Solvent delay: 5min.

3) testing process

301) standard solution configuration

It is 20 μ g/kg that the standard reserving solution of the phthalic ester of required test is diluted to concentration with normal hexane, 50 μ g/kg, 100 μ g/kg, 200 μ g/kg, 500 μ g/kg, 1mg/kg, the standard solution of 2mg/kg series.

302) Specification Curve of Increasing

The standard solution of preparation is carried out under the chromatographic condition of above-mentioned requirements to chromatographic determination, record retention time and response.Contrast table 1, table 2 are determined the retention time of each standard items and the respective items of response.Take response as ordinate, concentration is horizontal ordinate, and drawing standard curve obtains typical curve equation.

The quantitative and qualitative analysis of table 1, Mass Spectrometer Method phthalic ester is selected ion

Standard solution is measured

Configuration standard solution is to detect under the testing conditions of above-mentioned requirements, and result is as table 2, Fig. 1.

Table 2 plasticiser standard items testing result

In table 2, sequence number 1-17 is followed successively by: repefral (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), phthalic acid two (2-methoxy ethyl) ester (DMEP), phthalic acid two (4-methyl-2-amyl group) ester (BMPP), phthalic acid two (2-ethoxy) ethyl ester (DEEP), diamyl phthalate (DPP), dihexylphthalate (DHXP), butyl benzyl phthalate (BBP), phthalic acid two (2-butoxy) ethyl ester (DBEP), dicyclohexyl phthalate (DCHP), diisononyl phthalate (DINP), phthalic acid two (2-ethyl hexyl) ester (DEHP), diphenyl phthalate, the positive dioctyl ester of phthalic acid (DNOP), dinonyl phthalate (DNP).

303) sample detection

Get 2mL dairy products and 5mL cyclohexane is placed in glass centrifuge tube, vortex mixed 2min.Then in centrifuge tube, add 0.3g sodium chloride and 0.1g aluminium oxide, by centrifuge tube vortex vibration 3min, with the centrifugal 5min of 4000r/min, obtain machine testing sample.Under the condition of above-mentioned requirements, measure, record retention time and the response of each component.

4) result is calculated

In sample, the content of plasticiser calculates and obtains by chromatographic data process software or by formula (1):

$X_i=\frac{(c_i-c_0)\×V}{m}\×f......\left(1\right)$

In formula:

X _i---plasticiser content (i) in sample, unit is milligrams per kilogram (mg/kg) or milligrams per liter (mg/L);

C _i---(i) concentration corresponding to response of plasticiser in sample, unit is milligrams per liter (mg/L);

C ₀---plasticiser concentration (i) in blank sample, unit is milligrams per liter (mg/L);

V---sample constant volume, unit is milliliter (mL);

The quality of m---sample, unit is gram (g) or milliliter (mL);

F---extension rate.

Plasticiser (X in sample solution _i) response should be in the typical curve range of linearity, sample introduction analysis again after exceeding the range of linearity and should diluting.

Below above-mentioned detecting step is carried out to concrete test result description, repeat no more testing process and computation process, the case study on implementation of wherein enumerating all, carrying out on the same day pre-treatment, carries out upper machine testing on the same day.

Embodiment 1

Recovery test

Phthalic ester is containing many kinds of substance, and chemical property is similar.According to the requirement of [2011] No. 551 bulletins of the Ministry of Public Health, the Limited Doses regulation that three kinds of content of plasticizing agents in food are made, phthalic acid two (2-ethyl) own ester (DEHP), diisononyl phthalate (DINP), dibutyl phthalate (DBP) maximum residue limit are respectively 1.5mg/kg, 9.0mg/kg, 0.3mg/kg, and the elite DEHP of getting, DBP carry out assay.

In 16 kinds of phthalate compounds, the own ester spectrogram of selective scanning dibutyl phthalate and phthalic acid two (2-ethyl) is as Fig. 2, and DEHP, DBP standard model test retention time are as table 2.

Table 2, DBP, the retention time of DEHP

Title	Abbreviation	Retention time (min)	Quota ion	Auxiliary quota ion
					Dibutyl phthalate	DBP	10.372	149	223
The own ester of phthalic acid two (2-ethyl)	DEHP	18.695	149	167

According to above-mentioned standard items preparation and method of testing, record DEHP, DBP typical curve as Fig. 3, Fig. 4.

Add a certain amount of standard items to fresh milk, respectively do 2 parts of parallel sample according to above-mentioned sample treatment, done 3 variable concentrations (30ppb, 100ppb, 1ppm) and added, test result is as follows.

The background values DBP recording in sample is 7.19ppb, and DEHP is 1.52ppb, and difference adds under scalar case the recovery as table 3.

DBP in table 3, milk, the interpolation recovery of DEHP

Sequence number	Title	Add scalar (ppb)	Measured value (ppb)	The recovery
					1	DBP	30	43.22	120.10%
2	DBP	100	115.49	108.30%
					3	DBP	1000	953	94.60%
4	DEHP	30	34.58	110.20%
					5	DEHP	100	106.12	104.60%
6	DEHP	1000	923	92.10%

In the inventive method, only use cyclohexane to extract sample, the blank value that detects sample is extremely low, and (bottom line) content value of DBP, DEHP is respectively 7.19ppb, 1.52ppb.

Embodiment 2

Buy the plain chocolate of 4 kind different brands selling on market, according to the content of above-mentioned detection method selectivity test plasticiser dibutyl phthalate (DBP) and phthalic acid two (2-ethyl) own ester (DEHP), testing result is as table 4, and the detection collection of illustrative plates of sample 1-4 is followed successively by Fig. 5-8.

DBP in table 4,4 kinds of milk, the assay result of DEHP

Experimental result shows that the inventive method detects plasticiser, and testing process is simple, and the recovery is suitable, analyzes in tolerance interval normal detection.Can in the situation that condition is restricted, use, and obtain testing result accurately.

Listed a series of detailed description is above only illustrating for feasibility embodiment of the present invention; they are not in order to limit the scope of the invention, all do not depart from the equivalent embodiment that skill spirit of the present invention does or change and all should be included in protection scope of the present invention within.

Claims (4)

1. a method that detects plasticiser in dairy products, is characterized in that, comprises the following steps:

(1) preparation standard solution, utilizes gas chromatograph-mass spectrometer (GCMS) to detect it, obtains retention time, and generates typical curve corresponding between concentration and response;

(2) sample thief carries out pre-service, obtains machine testing sample, utilizes described gas chromatograph-mass spectrometer (GCMS) under the condition identical with step (1), it to be detected, and obtains retention time and response;

(3) retention time and the described typical curve that in the sample retention time obtaining in step (2) and response and step (1), obtain are compared, the content of plasticizing agent in calculative determination sample;

Pre-service in described step (2) comprises, measures raw milk or dairy products and cyclohexane and joins in glass centrifuge tube, vortex mixed 2～5min; Then in centrifuge tube, add sodium chloride and aluminium oxide, by centrifuge tube vortex vibration 2～5min, with the centrifugal 5～10min of 4000r/min rotating speed, get supernatant and detect.

2. the method for plasticiser in detection dairy products according to claim 1, is characterized in that, the pre-service in described step (2) comprises, takes sample 2mL plain chocolate and 5mL cyclohexane, is placed in centrifuge tube mesoscale eddies mixing 2min; Then in centrifuge tube, add 0.3g sodium chloride and 0.1g aluminium oxide, by centrifuge tube vortex vibration 3min, with the centrifugal 5min of 4000r/min, get supernatant and carry out upper machine testing.

3. the method for plasticiser in detection dairy products according to claim 1, is characterized in that, gas chromatograph-mass spectrometer (GCMS) testing conditions is:

Chromatographic condition: chromatographic column, HP-5MS quartz capillary, 30m × 0.25mm(i.d.) × 0.25 μ m; Injector temperature, 280 ℃; Heating schedule, 60 ℃ of initial column temperatures, keep 1min, are warming up to 220 ℃ with 20 ℃/min, keep 1min, then are warming up to 280 ℃ with 5 ℃/min, keep 4min; Carrier gas, nitrogen; Flow velocity 1ml/min; Input mode, Splitless injecting samples; Sample size, 1 μ l;

Mass spectrum condition: chromatogram and mass spectrometer interface temperature: 280 ℃; Ionization mode, electron bombardment ionization source (EI); Monitoring mode, selects ion scan pattern (SIM); Ionizing energy, 70eV; Solvent delay, 5min.

4. according to the application of the method for plasticiser in the detection dairy products described in the arbitrary claim of claim 1～3 plasticiser in detection raw milk.

Images