Related toxicity tests
1> Test method: Oral
Ingestion method: 3161 mg/kg
Test subject: Rodent - rat
Toxicity type: acute
Toxic effects: 1.Details of toxic effects not reported other than lethal dose value
2> Test method: Inhalation
p>Ingestion method: 3248 mg/m3
Test subject: Rodent - rat
Toxicity type: acute
Toxic effects: 1.Details of toxic effects not reported other than lethal dose value
3> Test method: Intraperitoneal
Ingestion method: 3200 mg/kg
Test subject: Rodent - rat
Toxicity type: acute
Toxic effects: 1.Sense Organs and Special Senses (Eye) - lacrimation
2.Behavioral - tremor
3.Lungs, Thorax, or Respiration - cyanosis
4> Test method: Unreported
Ingestion method: 6 mg/kg
Test subjects :Rodent - rat
Toxicity type: acute
Toxic effects: 1.Details of toxic effects not reported other than lethal dose value
5> Test method: Oral
Ingestion method: 3296 mg/kg
Test subject: Rodent - mouse
Toxicity type: acute
Toxic effects: 1.Details of toxic effects not reported other than lethal dose value
6> Test method: Intraperitoneal
Ingestion method: 800 mg/kg
Test subject :Rodent - mouse
Toxicity type: acute
Toxic effects: 1.Sense Organs and Special Senses (Eye) - lacrimation
2.Behavioral - tremor< /p>
3.Lungs, Thorax, or Respiration - cyanosis
7> Test method: Unreported
Ingestion method: 1 mg/kg
Test object: Rodent - mouse
Toxicity type: acute
Toxic effects: 1.Details of toxic effects not reported other than lethal dose value
8&g
t; Test method: Administration onto the skin
Ingestion method: >1 mg/kg
Test object: Rodent - rabbit
Toxicity type: acute < /p>
Toxic effects: 1.Details of toxic effects not reported other than lethal dose value
9> Test method: Oral
Ingestion method: 21840 mg/kg /4W-C
Test subject: Rodent - rat
Toxicity type: MultipleDose
Toxic effects: 1.Behavioral - food intake (animal)
2.Kidney, Ureter, Bladder - other changes
3.Nutritional and Gross Metabolic - weight loss or decreased weight gain
10> Test method: Oral
Ingestion method: 32760 mg/kg/13W-C
Test subject: Rodent - rat
Toxicity type: MultipleDose
Toxic effects: 1.Kidney, Ureter, Bladder - other changes
2.Related to Chronic Data - death
11> Test method: Oral
Ingestion method: 21 mg/kg/14D-C
Test subject: Rodent - rat
Toxicity type: MultipleDose
Toxic effects: 1.Kidney, Ureter, Bladder - inflammation , necrosis, or scarring of bladder
2.Nutritional and Gross Metabolic - weight loss or decreased weight gain
12> Test method: Inhalation
Ingestion method : 58 ug/m3/17W-I
Test subject: Rodent - rat
Toxicity type: MultipleDose
Toxic effects: 1.Liver - other changes< /p>
2.Blood - changes in serum composition (e.g. TP, bilirubin, cholesterol)
3.Biochemical - Enzyme inhibition, induction, or change in blood or tissue levels - transaminases
13> Test method: Oral
Ingestion method: 93600 mg/kg/13W-C
Test subject: Rodent - mouse
Toxicity Type: MultipleDose
Toxic effects: 1.Kidney, Ureter, Bladder - other changes
14&g
t; Test method: Oral
Ingestion method: 50400 mg/kg/14D-C
Test object: Rodent - mouse
Toxicity type: MultipleDose < /p>
Toxic effects: 1. Kidney, Ureter, Bladder - inflammation, necrosis, or scarring of bladder
15> Test method: Administration into the eye
Ingestion Method: 500 mg/24H
Test object: Rodent - rabbit
Toxicity type: SkinEyeIrrition
Toxicity effect: 1.Mild
16> Test method:
Ingestion method: 78 ug/well
Test object: Bacteria - Escherichia coli
Toxicity type: Mutation
< p> Toxic effects:17> Test method: Oral
Ingestion method: 1 mg/kg
Test subject: Rodent - mouse
Toxicity type: Mutation
Toxic effect:
18> Test method: Oral
Ingestion method: 195 mg/kg/2Y-C < /p>
Test subject: Rodent - rat
Toxicity type: Tumorigenic
Toxic effects: 1. Tumorigenic - Carcinogenic by RTECS criteria
2. Kidney, Ureter, Bladder - tumors
19> Test method: Oral
Ingestion method: 197 mg/kg/2Y-C
Test subject: Rodent - rat
Toxicity type: Tumorigenic
Toxic effects: 1.Tumorigenic - Carcinogenic by RTECS criteria
2.Kidney, Ureter, Bladder - tumors
20> Test method: Oral
Ingestion method: 162 mg/kg/2Y-C
Test subject: Rodent - rat
Toxicity Type: Tumorigenic
Toxic effects: 1.Tumorigenic - equivocal tumorigenic agent by RTECS criteria
2.Kidney, Ureter, Bladder - tumors
21> Test method :Inhalation
Ingestion method: 500 ug/m3, male 17 week(s) pre-mating
Test subject: Rodent - rat
Toxicity type: Reproductive
Toxic effects: 1.Reproductive - Paternal Effects - spermatogenesis (incl. genetic material, sperm morphology, motility
, and count)
2.Reproductive - Fertility - pre-implantation mortality (e.g. reduction in number of implants per female; total number of implants per corporalutea)
3.Reproductive - Effects on Embryo or Fetus - fetal death
[Edit this paragraph] How do families test whether dairy products contain melamine
1. Pour the milk powder into a thicker-than-usual amount with hot water, stir thoroughly until no solid lumps appear, then put it in the refrigerator and wait for the milk to cool down.
2. Prepare a black cloth and an empty cup. Put a black cloth over the mouth of the empty cup to serve as a filter.
3. Pour the cooled milk over a black cloth and strain.
4. If there is white solid filtered out, rinse it with clean water several times to eliminate other soluble matter.
5. If you find white crystals after rinsing, you can put the crystals into clean water. If the crystals sink to the bottom of the water. Then it is most likely melamine, and this milk powder cannot be used.
This method may not be able to detect trace amounts of melamine, but trace amounts of melamine make the possibility of children getting stones much lower, at least it can be a check.
The above methods are for reference only.
[Edit this paragraph] Professional chemical detection method to test melamine
GC-MS method to determine melamine in animal food
Spectra-Quad realizes online melamine content Detection
Ultra-high performance liquid chromatography_electrospray tandem mass spectrometry to determine the residual melamine in feed
Reversed-phase high performance liquid chromatography to determine the content of melamine in feed
< p> High-performance liquid chromatography-diode array method for determination of melamine in high-protein foodsHigh-performance liquid chromatography (HPLC) for determination of melamine in feed
High-performance liquid chromatography- Quadrupole mass spectrometry coupled to determination of melamine content in feed
Solid phase extraction coupled with high performance liquid chromatography for determination of melamine in pet food
Liquid chromatography tandem mass spectrometry (LC-MSMS )Analysis of melamine in pet food
Determination of melamine residues in feed by liquid chromatography-tandem mass spectrometry
Determination of melamine in animal food by GC-MS
1 Instruments and conditions
Agilent1100 high performance liquid chromatograph (Agilent Company, USA); diode array detector (DAD), detection wavelength 240nm, column temperature: 40°C.
(1) AgelaVenusilTMASBC18 (4.6×250mm); buffer: 10mM citric acid, 10mM sodium heptanesulfonate; mobile phase: buffer solution: acetonitrile=85:15; flow rate: 1.0mL/min.
(2) AgelaVenusilTMASBC8 (4.6×250mm); mobile phase: buffer: acetonitrile=85:15; buffer: 10mM citric acid, 10mM sodium octane sulfonate, adjust pH to 3.0; flow rate: 1.0mL/min;
Ion exchange solid phase extraction column AgelaClearnertTMPCX (Beijing Agela Technology Co., Ltd.)
2 Reagents and samples
Pet feed sample ( (provided by the Feed Supply Center of the Ministry of Agriculture); methanol and acetonitrile were provided by Beijing Aijer Technology Co., Ltd.; ammonia, lead acetate, and trichloroacetic acid were all purchased from Beijing Chemical Reagent Company; melamine standard, citric acid, and sodium octane sulfonate (Sigma Company); methanol is chromatographically pure, and everything else is chemically pure.
3 Experimental methods
3.1 Sample pretreatment method
(1) Standard sample preparation:
Take 50 mg of melamine standard, and Dissolve 20% methanol and adjust the volume to 50mL to obtain a 1000ppm standard solution. When used, dilute to the desired concentration with extraction solution (0.1% trichloroacetic acid).
(2) Extraction:
Weigh 5g of the feed sample, add 50ml of 0.1% trichloroacetic acid extract, mix thoroughly, add 2mL of 2% lead acetate solution, and sonicate for 20 minutes.
Then transfer part of the solution to a 10mL centrifuge tube, centrifuge at 8000rpm/min for 10min, and take 3mL of the supernatant and pass it through a mixed cation exchange column (PCX).
(3) Purification (PCX cartridge, 60mg/3mL):
a) Activation and equilibrium: 3mL methanol, 3mL water
b) Sample loading : Add 3mL of extraction solution
c) Elute: 3mL water; 3mL methanol; discard the eluent and drain the column.
d) Elution: 5mL 5% ammoniated methanol (v/v) for elution. (Preparation of 5% ammoniated methanol: 5mL ammonia water + 95mL methanol).
e) Concentration: 50°C, blow dry with nitrogen, dilute to 2 mL with 20% methanol/water, analyze by HPLC or GC/MS after derivatization.
3.2HPLC detection method
3.2.1 Melamine HPLC-UV detection method
Melamine is a highly polar compound that is retained on traditional reversed-phase C18 columns. Very poor. It requires ion pair reagent chromatography to achieve good retention and separation. According to the melamine detection method of the US Food and Drug Administration (FDA) and the melamine detection method published by the Ministry of Agriculture of China, Agela ASB is used. A series of hydrophilic chromatographic columns can achieve good separation results. The analysis chromatogram is as follows:
(a) Chromatographic column: VenusilASBC84.6×250mm; standard: FDA method; mobile phase: buffer: acetonitrile= 85:15; Buffer: 10mM citric acid, 10mM sodium octane sulfonate, adjust pH to 3.0; flow rate: 1.0mL/min; column temperature: 40oC; wavelength: 240nm
(b) Chromatographic column : VenusilASB-C184.6×250mm; Standard: Standard method issued by the Ministry of Agriculture of China; Buffer: 10mM citric acid, 10mM sodium heptanesulfonate; Mobile phase: Buffer solution: acetonitrile=85:15; Flow rate: 1.0mL/min ; Column temperature: 40°C; Wavelength: 240nm
3.2.2 Melamine LC-MS detection method
Due to the HPLC-UV method published by the FDA, an ion pair reagent is added to the mobile phase , thus limiting the use of liquid mass spectrometry methods; however, without using ion pair reagent chromatography, melamine is poorly retained on the traditional C18 column and cannot obtain better separation and quantification [3].
Based on this problem, Agela Technology Company independently developed a new method, using Agela ASB series hydrophilic chromatography columns, which can achieve effective retention and separation without ion pair reagents. Therefore, the mobile phase in the method does not contain ion pairing reagents and can be used for mass spectrometry detection.
Compared with the "UpdatedFCC Developmental Melamine Quantitation (HPLC-UV)" announced by the FDA in April 2007, this method greatly reduces the minimum detection limit (MSD: 0.5ppm; UV: 2ppm) and improves the detection sensitivity.
The spectra obtained by this method at ASB-C84.6×250mmASB-C184.6×250mm are as follows:
Figure 3 Spectrum of melamine detected by LC-MS method
p>Buffer: 10mM NH4AC; Mobile phase: Buffer::ACN=95:5; Flow rate: 1.0mL/min; Injection volume: The sample is first dissolved with 70% ACN to about 1mg/mL, and then dissolved with ACN Dilute to 0.1mg/mL, add 10uL; column temperature: 40℃; wavelength: 240nm
4 Results and discussion
4.1 Cation exchange column (PCX)
Melamine is weakly alkaline (weakly cationic compound), and a cation exchange column should generally be selected for the purification process. The hybrid cation exchange column (PCX) has two types of cation exchange and reversed-phase adsorption by bonding the sulfonic acid group (-SO3H) to the polar polymer polystyrene/divinylbenzene (PEP) adsorbent. mechanism, and has the following advantages:
a) The sample can be made cleaner and the sensitivity of the detection improved by washing with two different solutions (water/buffer solution with a certain pH value and organic solvent).
b) Good batch repeatability.
c) The recovery rate is high and the reproducibility is good. Even if the column runs dry, a high recovery rate can be obtained.
4.2 LC-MS method advantages:
(1) The detection process is simple: without adding ion pair reagents, melamine can be well retained and separated, avoiding the preparation of ion pair flow complex process of phase.
(2) Improved detection sensitivity: no ion pair reagent, can be used in mass spectrometry detectors, greatly reducing the minimum detection limit (MSD: 0.5ppm; UV: 2ppm).
(3) Reduced detection costs: Without ion-pairing reagents, there is no need to buy more expensive ion-pairing reagents, thus reducing detection costs.
(4) Extend the service life of the chromatographic column: avoid the impact of using ion pair reagents to reduce the service life of the chromatographic column.
(5) The chromatographic column used in this method is universal: whether it is the FDA method, the standard method issued by the Ministry of Agriculture of China, or the LC-MS method developed by our company, Agela )ASB series hydrophilic chromatography columns can obtain a good detection result, thus providing customers with a variety of choices.
Relevant persons from the National Food Quality Supervision and Inspection Center said that in the existing national standard milk powder testing, protein, fat, bacteria, etc. are mainly tested. Melamine is a chemical raw material and is not allowed to be added to food, so the existing standards will not include corresponding content. In other words, melamine is not a routine testing item. Under normal circumstances, few people would think of testing it.
[Edit this paragraph] The number of casualties caused by the melamine incident
It pointed out that as of 8:00 on September 21, various places reported that 12,892 infants and young children were being hospitalized for treatment due to consumption of infant milk powder, including 104 infants and young children with severe symptoms; 1,579 people had been cured and discharged.
The report also pointed out that a total of 39,965 infants and young children reported to have received outpatient treatment and consultation due to consumption of infant formula and have basically recovered.
Among all infants and young children receiving treatment, 81.87% were under 2 years old, 17.33% were between 2 and 3 years old, and 0.8% were over 3 years old. According to epidemiological investigations, these infants and young children who received treatment were basically related to the consumption of Sanlu brand infant formula milk powder, and no cases related to the consumption of liquid milk were found.
[Edit this paragraph] A rapid method that can detect melamine in 15 minutes
It is understood that testing whether food contains melamine is a complex process. At present, domestic testing departments mainly The method of analysis using liquid chromatography equipment requires professional operations, takes a long time, and is expensive to detect.
On October 1, the Ministry of Science and Technology solicited technologies and products for rapid detection of melamine in liquid milk and milk powder, and put forward three requirements: accurate detection of melamine, a detection limit less than or equal to 2 mg per kilogram per liter, and reproducibility. ; Suitable for on-site, rapid testing, the average testing time for each sample is less than 30 minutes (including sample pre-processing time); the cost of technical products or instruments and equipment is low, and the operating costs are low.
Dr. Liu Zhiguo, deputy director of the Department of Biological and Pharmaceutical Engineering of the school, said that he used the principle of mutual recognition between antigens and antibodies in immunology to produce antibody test strips that can specifically recognize melamine. By inserting it into diluted milk products, you can detect whether the milk products contain melamine. This method is fast and sensitive and does not require special technical training to master. The detection time can be controlled within 10 minutes, the detection limit can be as low as microgram level, and the cost is easy to control.
The main research direction of Dr. Yang Ming, director of the Department of Chemistry and Environmental Engineering of the school, is to detect melamine in milk powder, using chemical kits to determine the presence or absence of melamine in the sample, using ultraviolet-visible light Method, quantitative analysis based on the characteristic coefficients of melamine. This method also meets the three requirements set by the Ministry of Science and Technology.
According to reports, the rapid detection method for melamine developed by Wuhan Institute of Technology has now entered the national patent application process.
A 20-minute melamine detection reagent was launched at Lanzhou University
A chemical reagent that can quickly detect whether food contains melamine was recently launched at Lanzhou University. According to Chen Baohua, one of the researchers, a professor and doctoral supervisor at the School of Chemistry and Chemical Engineering of Lanzhou University, adding this chemical reagent to milk and other foods can quickly determine whether the food contains melamine substances through the color change of the food.
According to Chen Baohua, testing whether food contains melamine is a complicated process. At present, domestic testing departments mainly use liquid chromatography instrument analysis, which requires professional operations and takes a long time. Testing is expensive. In order to achieve the goal of rapid detection of melamine in food and conduct "batch inspection" of products from food companies, entrusted by the relevant departments of Gansu Province, the School of Chemistry and Chemical Engineering of Lanzhou University established a special research group, led by Chen Baohua, Huang Guosheng, and Zhang Haixia Professors take the lead and carry out scientific research. After repeated experiments, the research team successfully developed a chemical reagent for rapid detection of melamine in just 4 days.
It is understood that the use of this chemical reagent to test food is simple, fast, easy to operate and low-cost. After simple training, ordinary dairy farmers can master this technology. Take the detection of whether milk contains melamine as an example. Adding the chemical reagent to the milk can detect the result in just 20 minutes.
On the 28th, Tu Silong, deputy dean of the School of Chemistry and Chemical Engineering of Lanzhou University, said in an interview that the research team is further improving the technology of rapid detection chemical reagents to meet the requirements for qualitative and quantitative detection of substances. After the standard is established, a simple and easy-to-carry test kit will be made to promote application to farmers and food companies. According to Gansu Daily
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 the People’s Republic of China, the State Administration for Industry and Commerce, Announcement of the General Administration of Quality Supervision, Inspection and Quarantine, No. 25, 2008.
Melamine is neither a food raw material nor a food additive. It is prohibited to artificially add it to food. Anyone who artificially adds melamine to food will be held legally responsible. As a chemical raw material, melamine can be used in the production of plastics, coatings, adhesives, and food packaging materials. Data show that melamine can enter food from the environment, food packaging and other channels, and its content is very low. In order to ensure 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 has been specially formulated (hereinafter referred to as the limit value). 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 2.5 mg/kg. Products above 2.5 mg/kg are not allowed to be sold.
3. The limit value of melamine in other foods containing more than 15% milk is 2.5mg/kg. Products above 2.5mg/kg shall not be sold.
The above provisions shall be implemented from the date of issuance. October 7, 2008.
Melamine is not allowed to be added to any food, so there is no standard. To answer your question directly, there were no standards before. This time I take this opportunity to emphasize that we are conducting supervision and management with a temporary management limit value or limit level. It is used for supervision and management, not a standard.