1 & gt； Test method: oral examination
Intake pattern: 3 16 1 mg/kg.
Test object: rodents-rats.
Type of toxicity: acute
Toxic effect: 1. No detailed information about toxic effects was reported except the toxic dose value.
2> test method: inhalation
Intake pattern: 3248 mg/m3.
Test object: rodents-rats.
Type of toxicity: acute
Toxic effect: 1. No detailed information about toxic effects was reported except the toxic dose value.
3> test method: intraperitoneal injection
Intake mode: 3200 mg/kg.
Test object: rodents-rats.
Type of toxicity: acute
Toxic effect: 1. Sensory organs and special senses (eyes)-tears.
2. Behavior tremor
3. Lung, chest or breath-cyanosis
4> Test method: Not reported
Intake pattern: 6 mg/kg
Test object: rodents-rats.
Type of toxicity: acute
Toxic effect: 1. No detailed information about toxic effects was reported except the toxic dose value.
5> test method: oral examination
Intake pattern: 3296 mg/kg
Test object: rodents-mice
Type of toxicity: acute
Toxic effect: 1. No detailed information about toxic effects was reported except the toxic dose value.
6> test method: intraperitoneal injection.
Intake pattern: 800 mg/kg
Test object: rodents-mice
Type of toxicity: acute
Toxic effect: 1. Sensory organs and special senses (eyes)-tears.
2. Behavior tremor
3. Lung, chest or breath-cyanosis
7> Test method: Not reported
Intake pattern: 1 mg/kg.
Test object: rodents-mice
Type of toxicity: acute
Toxic effect: 1. No detailed information about toxic effects was reported except the toxic dose value.
8> test method: skin administration.
Intake pattern: > 1 mg/kg
Test object: rodent-rabbit
Type of toxicity: acute
Toxic effect: 1. No detailed information about toxic effects was reported except the toxic dose value.
9> test method: oral examination
Intake mode: 21840mg/kg/4w-c.
Test object: rodents-rats.
Toxicity type: multiple doses
Toxic effect: 1. Behavior-food intake (animals)
2. Kidney, ureter, bladder-other changes
3. Nutrition and total metabolism-weight loss or weight gain reduction
10 > test method: oral test.
Intake pattern: 32760mg/kg/13w-c.
Test object: rodents-rats.
Toxicity type: multiple doses
Toxic effect: 1. Kidney, ureter, blade-other changes.
2. Related to chronic data-death
1 1 & gt； Test method: oral examination
Intake pattern: 21mg/kg/14d-c.
Test object: rodents-rats.
Toxicity type: multiple doses
Toxic effect: 1. Kidney, ureter, blade infection, necrosis or blade scar.
2. Nutrition and total metabolism-weight loss or weight gain reduction
12 > test method: inhalation
Air intake mode: 58ug/m3/17w-i.
Test object: rodents-rats.
Toxicity type: multiple doses
Toxic effect: 1. Liver-other changes.
2. Changes of blood-serum components (such as total protein, bilirubin and cholesterol)
3. Biochemical-enzyme inhibition, induction or change at blood or tissue level-transaminase
13 > test method: oral test
Intake mode: 93600 mg/kg/13w-c.
Test object: rodents-mice
Toxicity type: multiple doses
Toxic effect: 1. Kidney, ureter, blade-other changes.
14 & gt； Test method: oral examination
Intake pattern: 50400 mg/kg/14d-c.
Test object: rodents-mice
Toxicity type: multiple doses
Toxic effect: 1. Kidney, ureter, blade infection, necrosis or blade scar.
15 > test method: eye administration.
Intake pattern: 500mg /24H.
Test object: rodent-rabbit
Toxicity type: skin irritation
Toxic effect: 1. mild
16 > test method:
Intake pattern: 78 μ g/hole
Test object: Bacillus-Escherichia coli
Type of toxicity: mutation
Toxic effects:
17 > test method: oral test
Intake pattern: 1 mg/kg.
Test object: rodents-mice
Type of toxicity: mutation
Toxic effects:
18 & gt； Test method: oral examination
Intake pattern:195 mg/kg/2y-c.
Test object: rodents-rats.
Type of toxicity: tumorigenic
Toxic effect: 1. Carcinogenic-carcinogenic according to rtecs standards.
2. Tumors of kidney, ureter and bladder
19 > test method: oral test
Intake pattern:197 mg/kg/2y-c.
Test object: rodents-rats.
Type of toxicity: tumorigenic
Toxic effect: 1. Carcinogenic-carcinogenic according to rtecs standards.
2. Tumors of kidney, ureter and bladder
20 >； Test method: oral examination
Intake pattern:162 mg/kg/2y-c.
Test object: rodents-rats.
Type of toxicity: tumorigenic
Toxic effect: 1. Carcinogenicity-a suspected tumorigenic agent according to rtecs standards.
2. Tumors of kidney, ureter and bladder
2 1 & gt； Test method: inhalation
Intake pattern: 500 μ g/m3, male 17 weeks before mating.
Test object: rodents-rats.
Type of toxicity: reproduction
Toxic effect: 1. Reproduction-paternal effect-spermatogenesis (including genetic material, sperm pathology, motility and counting).
2. Reproductive-reproductive-preimplantation mortality rate (for example, the number of implants per female is reduced; Total number of implants per mechanism
3. Reproduction-Effect on Embryo or Fetus-Fetal Death
[Edit this paragraph] How do families detect whether dairy products contain melamine?
1。 Wash the milk powder with hot water according to the weight thicker than usual, fully stir until there is no solid block, and then put it in the refrigerator to let the milk stand and cool.
2。 Prepare a black cloth and an empty cup. Cover the empty cup with a black cloth as a filter.
3。 Pour the cooled milk on a black cloth and filter.
4。 If the white solid is filtered out, rinse it with clear water several times to remove other soluble substances.
5。 If white crystals are found after washing, you can put the crystals in clean water. If the crystal sinks to the bottom of the water. That's probably melamine. This milk powder can't be used
This method may not be able to detect trace amounts of melamine, but trace amounts of melamine make children less likely to get stones, so at least it can be found out.
The above methods are for reference only.
[Edit this paragraph] Use professional chemical detection methods to detect melamine.
Determination of melamine in animal food by gas chromatography-mass spectrometry
On-line detection of melamine content by spectral quadrupole
Determination of residual melamine in feed by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry
Determination of melamine in feed by RP-HPLC
Determination of melamine in high protein food by high performance liquid chromatography-diode array method
Determination of melamine in feed by high performance liquid chromatography
Determination of melamine in feed by HPLC-quadrupole mass spectrometry
Determination of melamine in pet food by solid phase extraction-high performance liquid chromatography
Analysis of melamine in pet food by liquid chromatography -MSMS
Determination of melamine residues in feed by liquid chromatography-tandem mass spectrometry
Determination of melamine in animal food by gas chromatography-mass spectrometry
1 instruments and conditions
Agilent 1 100 High Performance Liquid Chromatograph (Agilent USA); Diode array detector with detection wavelength of 240nm and column temperature of 40℃.
( 1)agelavenustiltmasb 18(4.6×250mm)； Buffer: 10mM citric acid, 10mM sodium heptane sulfonate; Mobile phase: buffer solution: acetonitrile = 85:15; Flow rate: 1.0 ml/min.
(2)agelavenustiltmasb 8(4.6×250mm)； Mobile phase: buffer: acetonitrile = 85:15; Buffer: 10mM citric acid, 10mM sodium octane sulfonate, adjusted to pH 3.0, flow rate:1.0ml/min;
Ion exchange solid phase extraction column AgelaClearnertTMPCX (Beijing Aigeer Technology Co., Ltd.)
2 reagents and samples
Pet feed samples (provided by the Feed Supply Center of the Ministry of Agriculture); Methanol and acetonitrile are provided by Beijing Aigeer Technology Co., Ltd.; Ammonia, lead acetate and trichloroacetic acid are all purchased from Beijing Chemical Reagent Company. Melamine standard, citric acid and sodium octane sulfonate (Sigma); Methanol is chromatographically pure, while others are chemically pure.
3 experimental methods
3. 1 sample pretreatment method
(1) preparation of standard sample:
Take 50 mg of melamine standard, dissolve it in 20% methanol to 50 ml to obtain 1000ppm standard solution, and dilute it to the required concentration with the extract (0. 1% trichloroacetic acid) when using.
(2) Extraction:
Weigh 5g feed sample, add 50m l 0. 1% trichloroacetic acid extract, mix well, add 2mL2% lead acetate solution, and ultrasonic for 20min.
Then transfer part of the solution to a 10mL centrifuge tube, centrifuge at 8000rpm/min 10min, and take 3mL supernatant to a mixed cation exchange column (PCX).
(3) Purification (PCX column, 60mg/3ml):
A) Activation and equilibrium: 3 ml of methanol and 3 ml of water.
B) Loading: adding 3 ml of extractive solution.
C) Washing: 3 ml of water; 3mL methanol; Discard the eluent and drain the column.
D) Elution: Elute 5 ml of 5% ammoniated methanol (v/v). (Preparation of 5% ammoniated methanol: 5mL ammonia water +95mL methanol).
E) concentration: 50℃, dried with nitrogen, 20% methanol/water to 2mL, and then analyzed by HPLC or GC/MS after derivatization.
3.2 HPLC detection method
3.2. 1 HPLC-UV detection method for melamine
Melamine is a strong polar compound, which is poorly retained on the traditional reversed-phase C 18 chromatographic column. Only by ion pair reagent chromatography can it be well retained and separated. According to the detection method of melamine by the US Food and Drug Administration (FDA) and the melamine detection method published by the Ministry of Agriculture of China, good separation effect can be obtained by using Agela)ASB series hydrophilic chromatographic columns. The analytical chromatogram is as follows:
(a) chromatographic column: venus ilasb 84.6×250mm；; Standard: FDA method; Mobile phase: buffer: acetonitrile = 85:15; Buffer: 10mM citric acid, 10mM sodium octane sulfonate, adjusted to pH 3.0, flow rate:1.0ml/min; Column temperature: 40oC wavelength: 240 nm
(b) chromatographic column: venus ilasb-c184.6× 250 mm; Standard: the standard method promulgated by the Ministry of Agriculture of China; Buffer: 10mM citric acid, 10mM sodium heptane sulfonate; Mobile phase: buffer solution: acetonitrile = 85:15; Flow:1.0ml/min; Column temperature: 40℃; Wavelength: 240 nm
3.2.2 Detection method of melamine by liquid chromatography-mass spectrometry
In the HPLC-UV method published by FDA, ion pair reagents are added to the mobile phase, which limits the use of LC-MS method. However, if there is no ion pair reagent chromatography, the retention of melamine on the traditional C 18 column is poor, and it cannot be separated and quantified well [3].
Based on this problem, Igel Technology Company independently developed a new method, which can effectively retain and separate reagents without ion pairs by using Agela)ASB series hydrophilic chromatographic columns. Therefore, the mobile phase in this method does not contain ion pair reagents and can be used for mass spectrometry detection.
Compared with "Updating the HPLC-UV of Milla developed by DFCC" published by FDA in April FDA2007, this method greatly reduced the minimum detection limit (MSD:0.5 ppm；; Uv: 2 ppm), which improves the detection sensitivity.
The spectrograms obtained by this method in ASB-C 84.6× 250 mm ASB-C184.6× 250 mm are as follows:
Fig. 3 spectrum of melamine detected by liquid chromatography-mass spectrometry
Buffer:10mmh4ac; Mobile phase: buffer:: ACN = 95: 5; Flow:1.0ml/min; Sampling volume: the sample was dissolved with 70% acetonitrile to about 65438 0 mg/ml, diluted with acetonitrile to 0.65438 0 mg/ml, and injected with 65438±00uL；; Column temperature: 40℃; Wavelength: 240 nm
4 Results and discussion
4. 1 cation exchange column (PCX)
Melamine is weakly alkaline (weakly cationic compound), so cation exchange column should be generally selected in the purification process. Mixed cation exchange column (PCX) has two mechanisms of cation exchange and reverse adsorption by bonding sulfonic acid group (-SO3H) to polar polymer polystyrene/divinylbenzene (PEP) adsorbent, and has the following advantages:
A) Two different solutions (water/buffer solution with a certain pH value and organic solvent) can be used to make the sample cleaner and improve the detection sensitivity.
B) Good batch repeatability.
C) High recovery rate and good reproducibility, even if the column is dried.
4.2 Advantages of liquid chromatography-mass spectrometry:
The detection process of (1) is simple: melamine can be well retained and separated without adding ion-pair reagents, thus avoiding the tedious process of preparing ion-pair mobile phase.
(2) detection sensitivity is improved: there is no ion pair reagent, which can be used in mass spectrometry detector, greatly reducing the minimum detection limit (MSD:0.5 ppm；; Ultraviolet: 2ppm).
(3) Reducing the detection cost: No ion-pair reagents are used, and expensive ion-pair reagents are no longer needed to be purchased, thus reducing the detection cost.
(4) Prolonging the service life of the chromatographic column: avoiding the influence of using ions to reduce the service life of the chromatographic column.
(5) The chromatographic column used in this method is universal: regardless of the FDA method, the standard method issued by the Ministry of Agriculture of China, or the LC-MS method developed by our company, good test results can be obtained by using Agela)ASB series hydrophilic chromatographic columns, providing customers with a variety of choices.
A person from the National Food Quality Supervision and Inspection Center said that in the existing national standard milk powder testing, protein, fat, bacteria and other tests are mainly carried out. Melamine is a chemical raw material, which is not allowed to be added to food, so the existing standards will not have corresponding content. In other words, melamine is not a routine test item. Under normal circumstances, few people would think of testing it.
[Edit this paragraph] The number of casualties caused by the melamine incident
Xinhuanet Beijing, September 2 1 Sunday, when the Ministry of Health informed the medical treatment of Sanlu infant formula milk powder incident on September 2 1 day, it pointed out that as of 8: 00 on September 2 1 day, there were 2892 infants 12892 who were hospitalized for eating infant formula milk powder, including 4 severely ill infants 104; 1579 was cured and discharged before.
The circular also pointed out that a total of 39,965 infants were reported to have received outpatient treatment consultation and have basically recovered from eating infant milk powder.
Among all infants treated, infants under 2 years old accounted for 8 1.87%, infants aged 2-3 years old accounted for 17.33%, and infants over 3 years old accounted for 0.8%. According to epidemiological investigation, these treated infants are basically related to eating Sanlu brand infant formula, and no cases related to eating liquid milk have been found.
[Edit this paragraph]/kloc-a method for rapid detection of melamine in 0/5 minutes.
It is understood that it is a complicated process to detect whether melamine is contained in food. At present, domestic testing departments mainly adopt the method of liquid chromatograph instrument analysis, which requires professional operation, takes a long time and costs a lot. 10 10/month 1 day, the Ministry of Science and Technology collected the rapid detection technology and products of melamine in liquid milk and milk powder, and put forward three requirements: the detection limit of melamine is less than or equal to 2 mg/kg/L, which is reproducible; Suitable for on-site rapid detection, the average detection time of each sample is less than 30 minutes (including sample pretreatment time); The cost of technical products or instruments and equipment is low, and the operating cost is low.
Dr Liu Zhiguo, deputy director of the Department of Biological and Pharmaceutical Engineering, introduced that he used the principle of mutual recognition between antigen and antibody in immunology to make antibody test paper which can specifically recognize melamine. Just insert the test paper into the diluted dairy products, and you can detect whether the dairy products contain melamine. This method is fast, sensitive and can be mastered without special technical training. The detection time can be controlled within 10 minute, the detection limit can be as low as microgram, and the cost is easy to control.
Dr. Yang Ming, director of the Department of Chemistry and Environmental Engineering in our school, mainly focuses on the determination of melamine in milk powder with chemical kits, and quantitative analysis by ultraviolet-visible spectrophotometry according to the characteristic coefficient of melamine. This method also meets the three requirements put forward by the Ministry of Science and Technology.
It is reported that the rapid detection method of melamine developed by Wuhan University of Technology has now entered the national patent application procedure.
Lanzhou University gave a reagent for detecting melamine for 20 minutes.
A chemical reagent that can quickly detect whether food contains melamine has recently appeared in Lanzhou University. According to Chen Baohua, one of the researchers, a professor at the School of Chemistry and Chemical Engineering of Lanzhou University and a doctoral supervisor, adding this chemical reagent to milk and other foods can quickly determine whether the food contains melamine through the color change of the food.
According to Chen Baohua, it is a complicated process to detect whether there is melamine in food. At present, domestic testing departments mainly use liquid chromatography for analysis, which requires professional operation, takes a long time and costs a lot. In order to achieve the purpose of rapid detection of melamine in food, the products of food enterprises were inspected in batches. Entrusted by the relevant departments of Gansu Province, the College of Chemistry and Chemical Engineering of Lanzhou University set up a scientific research team headed by three professors, Chen Baohua, Huang Guosheng and Zhang Haixia. After repeated experiments, the research group successfully developed a chemical reagent for rapid detection of melamine in only four days.
It is understood that using this chemical reagent to detect food has the characteristics of simplicity, rapidity, easy operation and low detection cost. Ordinary dairy farmers can master this technology after simple training. Taking the detection of melamine in milk as an example, it takes only 20 minutes to detect the result by adding this chemical reagent to milk.
On the 28th, Tu, vice president of the School of Chemistry and Chemical Engineering of Lanzhou University, said in an interview that the research group is further improving the technology of rapid detection of chemical reagents. After reaching the required standards for qualitative and quantitative detection of substances, it was made into a simple and portable kit for popularization and application to farmers and food enterprises. According to Gansu Daily.
Announcement No.25, 2008 of the Ministry of Health of the People's Republic of China, the Ministry of Industry and Information Technology of the People's Republic of China, the Ministry of Agriculture of People's Republic of China (PRC), the State Administration for Industry and Commerce and the General Administration of Quality Supervision, Inspection and Quarantine.
Melamine is neither a food raw material nor a food additive. It is forbidden to artificially add it to food. Anyone who artificially adds melamine to food shall be investigated for legal responsibility according to law. Melamine, as a chemical raw material, can be used to produce plastics, coatings, adhesives and food packaging materials. Data show that melamine can enter food from the environment and food packaging, and the content is very low. In order to protect human health and ensure the quality and safety of milk and dairy products, the temporary management limit value of melamine in milk and dairy products (hereinafter referred to as the limit value) is formulated. The announcement is as follows:
1. The limit value of melamine in infant formula milk powder is 1mg/kg, and products higher than 1mg/kg are not allowed to be sold.
2. The limit value of melamine in liquid milk (including raw milk), milk powder and other formula milk powder is 2.5mg/kg, and products higher than 2.5mg/kg shall not be sold.
3. The limit value of melamine in other foods with milk content above 15% is 2.5mg/kg, and products with milk content above 2.5mg/kg shall not be sold.
The above provisions shall come into force as of the date of promulgation. June 7, 2008 +65438.
Melamine is not allowed to be added to any food, so there can be no standard. To answer your question directly, there has never been any standard before. This time, I want to take this opportunity to emphasize that we are a temporary management limit or limit level for supervision and management, which is used for supervision and management, not a standard.