Summary of the invention
An object of the present invention is to provide a kind of trimeric cyanamide monoclonal antibody.
Trimeric cyanamide monoclonal antibody provided by the present invention is to be that the trimeric cyanamide monoclonal antibody hybridoma cell strain MAL secretion of CGMCC No.3394 produces by deposit number.
Deposit number is that the trimeric cyanamide monoclonal antibody hybridoma cell strain MAL of CGMCC No.3394 also belongs to protection scope of the present invention.
The application of described monoclonal antibody in the enzyme linked immunological kit of preparation detection trimeric cyanamide also belongs to protection scope of the present invention.
Another object of the present invention provides a kind of enzyme linked immunological kit.
Enzyme linked immunological kit provided by the present invention is following 1), 2), 3) or 4) in arbitrary described enzyme linked immunological kit:
1) conjugate of melamine hapten and carrier proteins, described penicidin monoclonal antibody and enzyme labelling anti-antibody in the enzyme linked immunological kit; Wherein, described conjugate is as coating antigen;
2) comprise the enzyme labelling thing of melamine hapten, described penicidin monoclonal antibody and anti-antibody in the enzyme linked immunological kit; Wherein, described anti-antibody is as coating antigen;
3) comprise the enzyme labelling thing of melamine hapten, described penicidin monoclonal antibody in the enzyme linked immunological kit; Wherein, described penicidin monoclonal antibody is as coating antigen;
4) comprise the conjugate of melamine hapten and carrier proteins, the enzyme labelling thing of described penicidin monoclonal antibody in the enzyme linked immunological kit; Wherein, described conjugate is as coating antigen;
The structural formula of described melamine hapten is suc as formula shown in the I:
(formula I).
Described enzyme linked immunological kit comprises trimeric cyanamide standard solution, substrate colour developing liquid, washings, sample diluting liquid;
Described trimeric cyanamide standard solution is the trimeric cyanamide standard solution that concentration is respectively 0 μ g/L, 5 μ g/L, 20 μ g/L, 100 μ g/L, 500 μ g/L and 2500 μ g/L;
Also can comprise substrate colour developing liquid in above-mentioned arbitrary described test kit provided by the present invention; Described substrate colour developing liquid is made up of A liquid and B liquid, and A liquid is that concentration is the aqueous solution of the urea peroxide of 1.5%-2.5%, and B liquid is that concentration is the aqueous solution of the tetramethyl benzidine of 0.5%-1.5%.
Wherein, described A liquid is preferably the aqueous solution that concentration is 2% urea peroxide, and B liquid is preferably the aqueous solution that concentration is 1% tetramethyl benzidine.
Also can comprise washings in above-mentioned arbitrary described test kit provided by the present invention; Described washings is that concentration is the 0.005M-0.015M phosphate buffered saline buffer of 0.8%~1.2% polysorbas20 and the concentration sodiumazide that is 0.3%-0.7%.
Wherein, to be preferably concentration be that 1% polysorbas20 and concentration are the 0.01M phosphate buffered saline buffer of 0.5% sodiumazide to described washings.
Also can comprise sample concentration liquid in above-mentioned arbitrary described test kit provided by the present invention; Described sample concentration liquid is the phosphate buffered saline buffer of (0.03mol/L-0.05mol/L), and sample concentration liquid need dilute, and uses after becoming sample diluting liquid.
Wherein, described sample concentration liquid is preferably the phosphate buffered saline buffer that concentration is 0.04mol/L, and preferred extension rate is 20 times.
The conjugate of described melamine hapten and carrier proteins is meant that melamine hapten is at the trimeric cyanamide-carrier protein couplet thing that obtains by mixed anhydride method with carrier proteins.
The concrete conjugate that has following structural formula of the conjugate of above-mentioned arbitrary described melamine hapten and carrier proteins:
Wherein, n is the coupling ratio, is the arbitrary natural integer among the 1-30.
The described conjugate that is used for wrapping quilt, described carrier proteins can be bovine serum albumin, human serum albumin, mouse serum protein, thyroprotein (BCG), rabbit anteserum albumen, hemocyanin or oralbumin.
The marker enzyme of described enzyme labelling mixture is horseradish peroxidase or alkaline phosphatase, wherein preferred horseradish peroxidase; Anti-or the goat-anti rabbit of the sheep anti mouse two of enzyme labelling two is anti-adopts glutaraldehyde methods or sodium periodate method that marker enzyme and two is resisted to carry out coupling and obtain, horseradish peroxidase can adopt several different methods of the prior art with it and two anti-carry out coupling, as glutaraldehyde method, sodium periodate method etc., the present invention creates through secular work the sodium periodate method is improved, make it save time, reduce horseradish peroxidase (HRP) and two anti-concentration rates, saved starting material.
The detection principle of test kit is as follows:
When on the enzyme plate capillary strip, wrapping in advance by the conjugate of melamine hapten and carrier proteins, after adding sample solution or standard solution, add trimeric cyanamide monoclonal anti liquid solution again, in the sample on residual trimeric cyanamide or trimeric cyanamide standard substance and the enzyme plate melamine hapten of bag quilt compete the trimeric cyanamide monoclonal antibody with the conjugate of carrier proteins, add the enzyme labelling two anti-amplifications that carry out, with the colour developing of colour developing liquid, the content of trimeric cyanamide becomes negative correlation in sample light absorption value and the sample, relatively can draw the content of trimeric cyanamide in the sample with typical curve.Simultaneously also can be according to the depth of color on the enzyme plate, with the comparison of the series concentration trimeric cyanamide standard solution color concentration range of content of melamine in the judgement sample roughly.
When on the enzyme plate capillary strip, wrapping by two when anti-in advance, after adding trimeric cyanamide monoclonal antibody is hatched, add sample solution or standard solution, add enzyme labelling melamine hapten solution again, trimeric cyanamide in the sample or trimeric cyanamide standard substance and enzyme labelling melamine hapten competition trimeric cyanamide specific antibody, with colour developing liquid colour developing, the content of trimeric cyanamide becomes negative correlation in sample absorbance and the sample, relatively can draw the content of trimeric cyanamide in the sample with typical curve.Simultaneously also can be according to the shade on the enzyme plate, with the comparison of the series concentration trimeric cyanamide standard solution color concentration range of content of melamine in the judgement sample roughly.
When on the enzyme plate capillary strip, wrapping in advance by the trimeric cyanamide monoclonal antibody, after adding sample solution or standard solution, add enzyme labelling melamine hapten solution again, the competition of residual trimeric cyanamide or trimeric cyanamide standard substance and enzyme-labelled antigen is coated on the trimeric cyanamide monoclonal antibody on the enzyme plate in the sample, with the colour developing of colour developing liquid, the sample light absorption value becomes negative correlation with the content of trimeric cyanamide, relatively can draw the content of trimeric cyanamide in the sample with typical curve.Simultaneously also can be according to the shade on the enzyme plate, with the comparison of the trimeric cyanamide standard solution color of the series concentration concentration range of content of melamine in the judgement sample roughly.
When on the enzyme plate capillary strip, wrapping in advance by the conjugate of melamine hapten and carrier proteins, after adding sample solution or standard solution, add enzyme labelling trimeric cyanamide monoclonal anti liquid solution again, the melamine antigen competition trimeric cyanamide monoclonal antibody of bag quilt on trimeric cyanamide in the sample or trimeric cyanamide standard substance and the enzyme plate, with the colour developing of colour developing liquid, the content of trimeric cyanamide becomes negative correlation in sample light absorption value and the sample, relatively can draw the content of trimeric cyanamide in the sample with typical curve.Simultaneously also can be according to the shade on the enzyme plate, with the comparison of the series concentration trimeric cyanamide standard solution color concentration range of content of melamine in the judgement sample roughly.
Last purpose of the present invention provides the method for trimeric cyanamide in a kind of test sample.
The method of trimeric cyanamide comprises the steps: in the test sample provided by the present invention
1) testing sample is carried out pre-treatment, obtain sample to be tested solution;
2) with above-mentioned arbitrary described test kit described sample to be tested solution is detected;
The method of described pre-treatment be following a), b), c), d), e) and f) in arbitrary:
A) described testing sample is a milk powder; Whenever get the described milk powder of 0.8g-1.2g and be dissolved in the described sample diluting liquid of 8ml-12ml, mix, centrifugal, get supernatant liquor, be sample to be tested solution;
B) described testing sample is a milk; With described milk and described sample diluting liquid according to 1: volume ratio mixing (9-11), the solution that obtains is sample to be tested solution;
C) described testing sample is an egg; Every 0.8g-1.2g egg is extracted with the 8ml-12ml extraction agent, and the extracting solution that obtains is sample to be tested solution;
D) described testing sample is a pet food; Every 1.8g-2.2g pet food is extracted with the 8ml-12ml extraction agent, and the extracting solution that obtains is sample to be tested solution;
E) described testing sample is a feed; Every 0.8g-1.2g feed is extracted with the 8ml-12ml extraction agent, and the extracting solution that obtains is sample to be tested solution;
F) described testing sample is a wheat gluten; Every 0.1g-0.3g wheat gluten is extracted with the 8ml-12ml extraction agent, and the extracting solution that obtains is sample to be tested solution;
Consisting of of described extraction agent: by Na
2HPO
412H
2O, NaH
2PO
42H
2O, NaCl, Tween20 and water are formed, described Na
2HPO
412H
2The concentration of O in described extraction agent is 2.9g/L, described NaH
2PO
42H
2The concentration of O in described extraction agent is 0.2g/L, and the concentration of described NaCl in described extraction agent is 0.9g/L, and the concentration of described Tween20 in described extraction agent is 0.05g/L.
In the aforesaid method, the method of described extraction can comprise the steps: described egg, pet food, wheat gluten or feed are dissolved in the described extraction solution, mixing, ultrasonic extraction 0.8min-1.2min, whirlpool mixing 0.8min-1.2min, leave standstill 4.5min-5.5min, the centrifugal 5min-10min of 3000rpm-5000rpm gets supernatant liquor.Wherein, in the leaching process of described wheat gluten, carry out above-mentioned ultrasonic extraction, vortex, centrifugal after, also can comprise the step that recentrifuge extracts; The method that described recentrifuge extracts comprises the steps: that the supernatant liquor that obtains with above-mentioned ultrasonic extraction, vortex, after centrifugal dilutes, and at the centrifugal 9-11min of 10000-12000r/min, gets supernatant liquor then.
In the aforesaid method, in step (1) back, step (2) is preceding also can comprise the step that sample to be tested solution is diluted, and generally dilutes 10-20 doubly.
Detected result analytic process provided by the invention is:
With the absorbancy mean value (B) of the standard solution of each concentration that is obtained absorbance (B divided by first standardized solution (0 standard)
0) multiply by 100% again, i.e. percentage absorbance.Calculation formula is:
Percentage absorbance (%)=(B/B
0) * 100%
Semilog value with the concentration (μ g/L) of trimeric cyanamide standard solution is an X-axis, and the percentage absorbance is a Y-axis, the drawing standard graphic representation.With the percentage absorbance of same way calculation sample solution, the concentration of corresponding each sample then can be read the content of trimeric cyanamide the sample from typical curve.
The analysis of detected result also can be adopted regression equation method among the present invention, calculates sample solution concentration.
The analysis of detected result can also utilize computer professional software among the present invention, the be more convenient for real-time analysis of a large amount of samples of this method, and whole testing process only needs the short period, promptly can finish in the 1.5h.
Among the present invention the similar thing of trimeric cyanamide is carried out structure of modification, add spacerarm, give prominence to the trimeric cyanamide characteristic group, and synthesized the conjugate (coating antigen) of melamine antigen (immunogen), trimeric cyanamide and carrier proteins by mixed anhydride method.
Enzyme linked immunological kit of the present invention mainly adopts the content of trimeric cyanamide in the product that the indirect competitive ELISA method is qualitative or the detection by quantitative animal or human eats (particularly dairy products such as milk, milk powder and egg, feed etc.).Test kit of the present invention and detection method are low to the pre-treatment requirement of sample, and sample pretreatment process is simple, simultaneously the rapid detection batch samples; Adopt the trimeric cyanamide monoclonal antibody of high specific, the method for inspection is convenient and easy, has specificity height, highly sensitive, characteristics such as tolerance range is high, accuracy height.And enzyme linked immunological kit of the present invention, the screening that simple in structure, easy to use, low price, carrying convenience, detection method be efficient, accurate, easy, be suitable for on-the-spot batch samples.Test kit of the present invention will play a significant role in melamine detection.
Embodiment
Employed experimental technique is ordinary method if no special instructions among the following embodiment.
Used material, reagent etc. if no special instructions, all can obtain from commercial channels among the following embodiment.
Embodiment 1, melamine hapten, melamine antigen, trimeric cyanamide monoclonal antibody and preparation thereof
One, the synthetic and evaluation of melamine hapten
1, melamine hapten is synthetic
1) take by weighing 120mg 4,6-diamino-2-hydroxyl-1,3,5-triazines is (available from Acros Organics company, CAS number: 3397-62-4), 100 μ L 4-bromo-butyric acid ethyl esters, the 100mg anhydrous sodium carbonate places the 50mL flask, add 20mL acetone again, 70 ℃ were refluxed the evaporated under reduced pressure solvent 16 hours.
2) residue is dissolved in the 15mL methanol-hydrogen potassium oxide mixed solution (15%, 88mg potassium hydroxide is dissolved in 5mL methyl alcohol), and 80 ℃ were refluxed the evaporated under reduced pressure solvent 1 hour.
3) add 8mL distilled water (all dissolvings) in residue, it was 3 (white precipitate occurring) that the HCl of 2M is acidified to pH.
4) centrifugal collecting precipitation, 50 ℃ of oven dry.Obtain reaction product (melamine hapten) 143mg, productive rate is 68%.
2, the evaluation of melamine hapten
The melamine hapten that step 1 is prepared carries out evaluation of ESI mass spectrum and ultimate analysis.
Mass spectrum is seen Fig. 1.Melamine hapten has molecular ion peak 212 (M-1).
Results of elemental analyses (%): C, 39.44; H, 5.20; N, 32.85; O, 22.51.
Analytical results shows: contain 3 O in the melamine hapten molecule, and 7 C, structure is suc as formula shown in (I), and molecular weight is 213.
The molecular structural formula of melamine hapten is suc as formula shown in the I:
(formula I).
Two, the synthetic and evaluation of melamine antigen
Trimeric cyanamide is a small-molecule substance, has only immunoreactivity, does not have immunogenicity, can not bring out body and produce immunne response, must with the macromolecular carrier albumen coupling after just have immunogenicity.Therefore with the similar thing 4 of trimeric cyanamide, 6-diamino-2-hydroxyl-1,3,5-triazines and 4-bromo-butyric acid ethyl ester production of melamine haptens, pick out a spacerarm and give prominence to characteristic group in the molecular structure, make the melamine antibody of preparation very high the specificity of trimeric cyanamide.
(1) trimeric cyanamide is immunogenic synthetic
1, synthetic
1) with the 10mg melamine hapten, be dissolved in the 1mL diox, stirring is dissolved it fully; Add the anhydrous tri-n-butylamine of 50 μ L then, place 4 ℃ of ice baths to cool off in this mixture, and stirred 15 minutes.Add the isobutyl chlorocarbonate that 25 μ L heavily steam, stirred 30 minutes about 4 ℃.
2) it is soluble in water to take by weighing 50mg bovine serum albumin (BSA), stirs to make its dissolving, transfers pH to 9.0 with the NaOH of 0.1mol/L; The haptens solution that step 1 is obtained dropwise joins in the dissolved albumen, and in 4 ℃ of gentle agitation 4 hours, whole process was kept pH 9.0.
3) with mixture in 4 ℃ at 0.1mol/L, among the PBS of pH 7.4 dialysis 72 hours, changed dialyzate 1 time every 6 hours.After the lyophilize in-20 ℃ of preservations.
2, the evaluation of melamine antigen
In the ratio of used haptens, carrier proteins and coupled product of production of melamine immunizing antigen reaction, carry out ultraviolet (200nm-400nm) scanning respectively and identify, and calculate its binding ratio by comparing the light absorption value of three under same wavelength.The ultraviolet spectrogram of product (Fig. 2) is compared with bovine serum albumin (BSA) variation has been taken place, and illustrates that haptens makes artificial antigen of melamine with BSA success coupling.As calculated, the binding ratio of melamine hapten molecule and BSA molecule is 21: 1.The molecular structural formula of melamine antigen is suc as formula shown in the II.
(2) preparation of trimeric cyanamide coating antigen
Method is identical with method therefor in the experiment (), and different is that used carrier proteins is an ovalbumin.The structural formula of conjugate is shown in formula III.
Three, trimeric cyanamide MONOCLONAL ANTIBODIES SPECIFIC FOR
To test the immunogen that obtains in two is immunogen.
A. animal immune
Experiment two immunogens that obtain are injected in the Balb/c mouse body, and immunizing dose is 75 μ g/, makes it produce antiserum(antisera).
B. cytogamy and cloning
Get immune Balb/c mouse boosting cell, merge, adopt indirect competitive ELISA to measure cell conditioned medium liquid, screen positive hole in 5: 1 (quantitative proportion) ratios and SP2/0 myeloma cell.Utilize limiting dilution assay that cloning is carried out in positive hole, obtain the hybridoma cell strain of stably excreting trimeric cyanamide monoclonal antibody up to screening, with this cell strain called after MAL, the strain of classification called after trimeric cyanamide monoclonal antibody hybridoma cell, this cell strain is preserved in China Committee for Culture Collection of Microorganisms common micro-organisms center on November 3rd, 2009 and (is called for short CGMCC, address: Datun Road, Chaoyang District, Beijing City, Institute of Microorganism, Academia Sinica, postcode 100101), preserving number is CGMCC No.3394.
C. cell cryopreservation and recovery
MAL makes 1 * 10 with frozen storing liquid with the strain of trimeric cyanamide monoclonal antibody hybridoma cell
6The cell suspension of individual/ml is in the medium-term and long-term preservation of liquid nitrogen.Take out frozen pipe during recovery, put into 37 ℃ of water-bath middling speeds immediately and melt, behind the centrifugal removal frozen storing liquid, move in the culturing bottle and cultivate.
D. MONOCLONAL ANTIBODIES SPECIFIC FOR and purifying
Increment culture method: trimeric cyanamide monoclonal antibody hybridoma cell strain MAL CGMCC No.3394 is placed cell culture medium, under 37 ℃ of conditions, cultivate, with sad-saturated ammonium sulphate method the nutrient solution that obtains is carried out purifying, obtain monoclonal antibody ,-20 ℃ of preservations.
Described cell culture medium is to add calf serum and sodium bicarbonate in the RPMI-1640 substratum, making the final concentration of calf serum in cell culture medium is 20% (quality percentage composition), and making the final concentration of sodium bicarbonate in cell culture medium is 0.2% (quality percentage composition); The pH of described cell culture medium is 7.4.
Said monoclonal antibody can also be taked following method preparation: the Balb/c mouse peritoneal is only injected sterilization paraffin oil 0.4mL/, 7 days pneumoretroperitoneum injection trimeric cyanamide monoclonal antibody hybridoma cell strain MAL 5 * 10
5Individual/as only, to gather ascites after 7 days.Carry out purifying with sad-saturated ammonium sulphate method, the ascites behind the purifying is put into-20 ℃ of environment and is preserved.
Four, Polyclonal Antibody Preparation
Adopt new zealand white rabbit as immune animal, with compound shown in the formula II is immunogen, immunizing dose is 1.5mg/kg, Freund's complete adjuvant with immunogen and equivalent when head exempts from is mixed and made into emulsifying agent, the subcutaneous multi-point injection of nape portion, getting the same dose immunogen 3~4 weeks adds equivalent Freund's incomplete adjuvant mixing and emulsifying at interval, and booster immunization is once, immunity is 5 times altogether, does not add adjuvant for the last time.Serum antibody titer is measured in last immunity blood sampling after 10 days, and heart is taken a blood sample, and obtains the polyclonal antibody of purifying with ammonium sulfate precipitation.
Five, trimeric cyanamide monoclonal antibody effect
Utilize chessboard method to carry out the mensuration that monoclonal antibody is tired, the result shows that tiring of trimeric cyanamide monoclonal antibody is 2.8 * 10
6, lowest detectable limit (LOD value) is that 5 μ g/L are and half amount of suppression (IC
50) be 10.6 μ g/L.
The enzyme linked immunological kit of embodiment 2, detection trimeric cyanamide
One, enzyme linked immunological kit is made up of following substances:
1, trimeric cyanamide coating antigen; As described in example 1 above.
2, enzyme plate;
3, trimeric cyanamide monoclonal antibody: by deposit number is that the trimeric cyanamide monoclonal antibody hybridoma cell strain MAL secretion of CGMCC No.3394 produces;
4, trimeric cyanamide standard substance: standard solution concentration is respectively 0 μ g/L, 5 μ g/L, 20 μ g/L, 100 μ g/L, 500 μ g/L and 2500 μ g/L; The trimeric cyanamide standard substance are available from Sigma Aldrich company; CAS number: 108-78-1; Be diluted to above-mentioned each concentration with sample diluting liquid;
5, anti-with the sheep anti mouse two of horseradish peroxidase-labeled;
6, substrate colour developing liquid: be made up of A liquid and B liquid, A liquid is the aqueous solution of 2% urea peroxide, and B liquid is the aqueous solution of 1% tetramethyl benzidine;
7, stop buffer: the 2mol/L vitriolic aqueous solution or 2mol/L aqueous solution of hydrochloric acid;
8, washings: contain the 0.01M phosphate buffered saline buffer of 0.8%~1.2% polysorbas20 and 0.5% sodiumazide, pH 7.4;
9, the phosphate buffered saline buffer of sample diluting liquid: 20 * 0.04mol/L.
Two, the preparation of each component in the test kit
1, is coated with the preparation of the enzyme plate of conjugate
Be cushioned trimeric cyanamide that liquid makes step 1 and the conjugate of carrier proteins is diluted to 10.0 μ g/mL with bag, every hole adds 100 μ L, 37 ℃ of incubation 2h, the coating buffer that inclines dilutes 20 times of after scouring 3 times with washings, each 30s, pat dry, in every hole, add 200 μ L confining liquids, 37 ℃ of incubation 2h then, the liquid in the hole that inclines, preserve with the vacuum-sealing of aluminium film dry back.
Bag is cushioned the sodium citrate buffer solution of liquid: pH9.6,0.01~0.1mol/L;
Confining liquid: phosphate buffered saline buffer: contain 0.5% horse serum, 1 ‰ sodiumazide, 3% caseic phosphate buffered saline buffer.
2, the anti-preparation of the sheep anti mouse two of horseradish peroxidase-labeled
2.1, two anti-preparation process
Sheep anti mouse two is anti-: as immune animal, is that immunogen to pathogen-free domestic goat carry out immunity with mouse source antibody with goat, and it is anti-to obtain sheep anti mouse two;
Goat-anti rabbit two is anti-: as immune animal, is that immunogen to pathogen-free domestic goat carry out immunity with rabbit source antibody with goat, and it is anti-to obtain goat-anti rabbit two.
2.2, enzyme labelling sheep anti mouse two is anti-
Carry out coupling with horseradish peroxidase (HRP) with sheep anti mouse two is anti-, the method for employing is the sodium periodate method of improvement, and method is as follows:
A, 8mg horseradish peroxidase are dissolved in the 2mL distilled water.
The 100mmol/L NaIO of b, the existing preparation of adding
4Solution 0.4mL, stirring at room reaction 20min.
C, usefulness 1mmol/L acetate buffer are removed unnecessary NaIO in 4 ℃ of dialysed overnight
4, make self link coupled enzyme reduction simultaneously.
D, adding phosphate buffered saline buffer (pH8.6,0.5mol/L) 40 μ L and phosphate buffered saline buffer (pH 8.6, the 5mol/L) 2.0mL that contains IgG 16mg, stirring at room reaction 4 hours.
The NaBH of e, the existing preparation of adding
4The aqueous solution (1mol/L) 0.1mL is 4 ℃ of reactions 4 hours, with reduction Schiff alkali.
F, purification storage.
Three, with the trimeric cyanamide in the enzyme linked immunological kit test sample
(1) detection method
1, sample pre-treatments
(1) with the trimeric cyanamide be the treatment step of the milk-product sample (milk, milk powder) of foodstuff additive:
The acquisition of milk powder test sample solution: get 1g milk powder and be dissolved in the dilution of 10mL sample liquid, mix, 4 ℃, the centrifugal 10min of 4000r/min get 50 μ L and are used for detecting.
The acquisition of milk detecting sample solution: fresh milk directly with detecting after the sample liquid dilution, got 50 μ L and be used for detecting according to 1: 10 by ratio.
(2) with the trimeric cyanamide be the treatment step of the food samples (eggs, pet food, feed, gluten) of foodstuff additive:
The acquisition of egg test sample solution: get the 1g sample and add in the 10mL extraction solution, and thermal agitation.Ultrasonic extraction 1min, whirlpool mixing 1min leaves standstill 5min then, make sample layering cooling after, the centrifugal 10min of 5000r/min gets supernatant liquor, and supernatant liquor is collected in the clean tube,, gets 50 μ L and analyzes 10 times of supernatant liquor dilutions with sample diluting liquid.
The acquisition of pet food test sample solution: get the equal quality sample of 2g and add in the 10mL extraction solution, and thermal agitation.Ultrasonic extraction 1min, whirlpool mixing 1min leaves standstill 5min then, after making sample layering cooling, behind the centrifugal 5min of 3000r/min room temperature, get supernatant liquor, and supernatant liquor is collected in the clean tube,, get 50 μ L and analyze 20 times of supernatant liquor dilutions with sample diluting liquid.
The acquisition of wheat gluten test sample solution: get the good sample of 0.2g homogeneous and add in the 10mL extraction solution, and thermal agitation.Ultrasonic extraction 1min, whirlpool mixing 1min leaves standstill 5min then, make sample layering cooling after, behind the centrifugal 5min of 3000r/min room temperature, get the supernatant liquor note and make supernatant liquor I; With sample diluting liquid according to 1: 10 volume ratio dilution supernatant liquor I after, the centrifugal 10min of 10000r/min gets the supernatant liquor note and makes supernatant liquor II; And supernatant liquor II is collected in the clean tube,, get 50 μ L and analyze 20 times of supernatant liquor II dilutions with sample diluting liquid.
The acquisition of feed test sample solution: get the 1g sample and add in the 10mL extraction solution, and thermal agitation.Ultrasonic extraction 1min, whirlpool mixing 1min leaves standstill 5min then, after making sample layering cooling, behind the centrifugal 5min of 3000r/min room temperature, get supernatant liquor, and supernatant liquor is collected in the clean tube,, get 50 μ L and analyze 20 times of supernatant liquor dilutions with sample diluting liquid.
Extract consisting of of solution:.
2. detect with test kit
2.1 the making of typical curve
In the enzyme plate micropore that is coated with conjugate described in the embodiment 1, add trimeric cyanamide standard solution 50 μ L, add trimeric cyanamide monoclonal antibody working fluid 50 μ L again, with cover plate film shrouding, react 30min in 37 ℃ of thermostat containers, pour out liquid in the hole, every hole adds 250 μ L washingss, pours out liquid in the hole behind the 30s, so repetitive operation is washed plate 5 times altogether, pats dry with thieving paper.The sheep anti mouse two anti-working fluid 100 μ L that add horseradish peroxidase-labeled, react 30min in 37 ℃ of thermostat containers, pour out liquid in the hole, the repeated washing step, every hole adds substrate colour developing liquid A liquid urea peroxide, substrate colour developing liquid B liquid tetramethyl benzidine (TMB), the mixing that vibrates gently, 37 ℃ of thermostat container lucifuge colour developing 15min, every hole adds the 2mol/L stop buffer vitriolic aqueous solution 50 μ L, the mixing that vibrates is gently used microplate reader, measures every hole absorbance.
With the absorbancy mean value (B) of the standard solution of each concentration absorbance (B divided by first standard solution (0 standard)
0) multiply by 100% again, obtain the percentage absorbance.Semilog value with trimeric cyanamide standard substance concentration (μ g/L) is an X-axis, and the percentage absorbance is a Y-axis, the drawing standard graphic representation.The typical curve that obtains as shown in Figure 3.
Percentage absorbance (%)=(B/B
0) * 100%
2.2 the mensuration of melamine concentration in the sample
In the enzyme plate micropore that is coated with conjugate described in the embodiment 1, add test sample solution 50 μ L, add trimeric cyanamide monoclonal antibody working fluid 50 μ L again, with cover plate film shrouding, react 30min in 37 ℃ of thermostat containers, pour out liquid in the hole, every hole adds 250 μ L washingss, pours out liquid in the hole behind the 30s, so repetitive operation is washed plate 5 times altogether, pats dry with thieving paper.The sheep anti mouse two anti-working fluid 100 μ L that add horseradish peroxidase-labeled, react 30min in 37 ℃ of thermostat containers, pour out liquid in the hole, the repeated washing step, every hole adds substrate colour developing liquid A liquid urea peroxide, substrate colour developing liquid B liquid tetramethyl benzidine (TMB), the mixing that vibrates gently, 37 ℃ of thermostat container lucifuge colour developing 15min, every hole adds the 2mol/L stop buffer vitriolic aqueous solution 50 μ L, the mixing that vibrates is gently used microplate reader, measures every hole absorbance.
With the absorbancy mean value (B) of each test sample solution absorbance (B divided by first standard solution (0 standard)
0) multiply by 100% again, obtain the percentage absorbance.The percentage absorbance of corresponding each test sample solution, the residual quantity that then can read the trimeric cyanamide the test sample solution from typical curve.
(2) detection of enzyme linked immunological kit effect
1, standard substance precision test
Prepare test kit according to method described in the embodiment 1, respectively extract 10 test kits (i.e. 10 enzyme plates) and experimentize from the test kit of 3 different batches, each enzyme plate is extracted 20 micropores out, measures the absorbance of 20 μ g/L standardized solution, calculate the variation coefficient, the results are shown in Table 1.
The method of calculation of the variation coefficient: the variation coefficient (the CV)=standard deviation of measurement result and the per-cent of its mean value.
Table 1 standard substance Precision test result (CV%)
Can draw by above-mentioned test-results, every batch of test kit measured 10 standard substance variation coefficient between 4.8% ~ 10.2%, meets precision and is less than or equal to 20% regulation.
2, sample precision test
In the sample that does not contain trimeric cyanamide (milk, milk powder, cat grain, egg and feed), add trimeric cyanamide, make the final concentration of trimeric cyanamide in sample be respectively 0.16mg/L, 2.0mg/kg, 10.0mg/kg, 20.0mg/kg, 50.0mg/kg; Sample after adding is carried out pre-treatment according to method described in the embodiment 2 respectively, obtain test sample solution.
Respectively extract 3 test kits and detect from the test kit of three different batches, each experiment repeats 5 times, calculates the variation coefficient respectively.The result sees Table 2-table 6 respectively.
The method of calculation of plate within variance coefficient: certain sample (being generally medium level) replication number of times gained result's the variation coefficient in plate within variance coefficient=same same block of plate of once measuring.
The method of calculation of variation within batch coefficient: the variation within batch coefficient=variation coefficient of each parallel samples in once measuring together.
The method of calculation of interassay coefficient of variation: interassay coefficient of variation=same sample is got its mean value in the variation coefficient of different batches measurement result.
The Precision test result of table 2, milk (adding concentration 0.16mg/L)
Table 3, powdered milk sample precision test (adding concentration 2.0mg/kg)
Table 4, cat grain sample precision test (adding concentration 10.0mg/kg)
Table 5, egg sample precision test (adding concentration 20.0mg/kg)
Table 6, feed sample precision test (adding concentration 50.0mg/kg)
The result shows that this test kit adds sample to above 5 kinds, and the plate within variance coefficient is less than 10%, and the variation within batch coefficient is less than 15%, and interassay coefficient of variation satisfies the regulation of test kit precision less than 20%.
3, sample recovery test
In the sample that does not contain trimeric cyanamide (milk, milk powder, cat grain, egg and feed), add the trimeric cyanamide standard substance of different concns respectively, carry out pre-treatment, obtain sample solution, detect again according to method described in the embodiment 2.Each concentration do 5 parallel, calculate recovery rate (rate of recovery=measured value/interpolation value) respectively.
The results are shown in Table 7, table 8.
The sample determination of recovery rates (1) of table 7, test kit
The sample determination of recovery rates (2) of table 8, test kit
From table, can find out that the interpolation rate of recovery of milk sample is between 72.1% ~ 94.1%; The interpolation rate of recovery of milk powder and cat grain sample is between 66.2% ~ 99.8%; The interpolation rate of recovery of egg and feed sample is 62.4% ~ 95.8%, meets the bioassay standard of accuracy.
4, cross reacting rate test:
Select and the compound of the similar structure of trimeric cyanamide and the representative veterinary drug of clinical use, measure cross reacting rate.Obtain its 50% inhibition concentration respectively by various typical curves.Calculate the cross reacting rate of test kit with following formula to other analogue.
The result is as shown in table 9.
The specificity of table 9, test kit
Title |
Cross reacting rate (%) |
Trimeric cyanamide |
100.0 |
Tricyanic acid |
<10 |
Cyanuramide |
<0.1 |
Cyanurodiamide |
<0.1 |
Other triazines analogues |
<0.1 |
Tsiklomitsin |
<0.1 |
Gentamicin |
<0.1 |
Penbritin |
<0.1 |
Experiment shows that test kit of the present invention is good to the specificity of trimeric cyanamide, and test kit promptly of the present invention can detect trimeric cyanamide.
5, test kit preservation period test
The test kit preservation condition is 2-8 ℃, and through 12 months mensuration, the maximum absorbance value (zero standard) of test kit, 50% inhibition concentration, trimeric cyanamide added the practical measurement value all within normal range.Consider in transportation and the use, have improper preservation condition and occur, test kit was placed 8 days that carry out the accelerated deterioration experiment, the result shows that every index of this test kit meets the requirements fully under the condition of 37 ℃ of preservations.Consider that the freezing situation of test kit takes place, test kit was put into-20 ℃ of refrigerators freezing 8 days, measurement result shows that also the every index of test kit is normal fully.Can draw test kit from above result can preserve more than 12 months at least at 2-8 ℃.