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Aflatoxin harm:
Aflatoxins are toxic metabolites of a class of fungi such as Aspergillus flavus and Aspergillus parasiticus, which are highly carcinogenic and are found mainly in cereals, nuts, cottonseed, and in products related to human blood and animal feed. Its toxicity is much higher than that of cyanide, arsenide and organic pesticides, among which B 1 is the most toxic. When a person consumes a large amount, acute poisoning may occur, and acute hepatitis, hemorrhagic necrosis, hepatic steatosis, and bile duct hyperplasia may occur. When the trace is continuously ingested, it can cause chronic poisoning, growth disorders, and cause fibrous lesions, resulting in fibrous tissue hyperplasia.
National attention:
In recent years, the state has developed a number of methodological standards for the detection of aflatoxins, and at the same time introduced a limited amount of aflatoxin in food and feed, showing the great harm of aflatoxin, using an effective method to detect aflatoxin, thereby controlling toxic Food is vital to the harm of animals and humans. As the earliest high-tech enterprise engaged in the detection of mycotoxins in China , Huaan McKee also has a profound exploration and research on aflatoxin detection. Let us share with you our practice.
Current detection method for aflatoxin
Detection method
Guideline
advantage
Disadvantage
High performance liquid chromatography (HPLC)
GB/T 18979
High specificity and high sensitivity
More expensive equipment
Thin layer chromatography (TLC)
GB/T 8381
Simple and easy to popularize
Sample handling is cumbersome and harmful to people
Enzyme linked immunosorbent assay (ELISA)
GB/T 17480
Strong specificity, high sensitivity and low cost
There are a few false positive results
Colloidal gold immunochromatography
Strong specificity and low cost
Qualitative detection
How to choose the detection method and the unfamiliar instrument detection method is plagued by many testers. This time, I mainly introduce the relatively high cost performance of the instrument method, which is also the high-performance liquid chromatography (HPLC) commonly used by many testers:
ã€principle】:
The sample is extracted with methanol-water, the extract is filtered, diluted, and the filtrate is purified by immunoaffinity column chromatography containing aflatoxin-specific antibody . The aflatoxin is cross-linked to the antibody in the chromatographic medium, and the antibody is against Aspergillus flavus. The toxins B 1 , B 2 , G 1 and G 2 have specificity, and the impurities on the immunoaffinity column are removed by water, eluted with methanol through an immunoaffinity column, and then derivatized by a photochemical derivatization column to improve detection accuracy. Sex.
[Main reagents and consumables]:
ToxinFast ® air control operating frame : air pump
ToxinFast ® aflatoxin immunoaffinity column 1ml or 3ml
ToxinFast ® Photochemical Derivatives
ToxinFast ® glass microfiber filter paper : diameter 11cm, aperture 1.5μm
ToxinFast ® glass test tube : 12mm in diameter, 75mm in length, no fluorescence
ToxinFast ® syringe : 10ml, 20ml
[Detection steps]:
Sample pulverization - extraction - eluent injection, affinity column purification - chemical derivation - detection of values ​​(all of these steps are known in the liquid phase, here is a brief mention, mainly why the gas is used The control frame and chemical derivative are explained below!)
Instructions for use of the air control operating frame:
After the sample is pulverized, it needs to be cleaned by the affinity column, which is how to facilitate the operation of the affinity column. The air control operation frame can effectively improve the working efficiency of this link (very convenient operation), as shown in the figure:
1 Connect the assembled air control frame to connect the immunoaffinity column and the syringe syringe to the air control operating frame.
2 loading the treated solution;
3 adjust the air pump knob to control the flow rate, so that the sample liquid flows out at a speed of 1-2d/s;
4, the sample solution is completely drained, washed twice with deionized water or distilled water at a flow rate of 2-3d / s, each time 10ml;
5. After the liquid is completely drained, place the vial under the affinity column and load 1 ml of methanol to flow out at 1 d/s until it is completely drained.
The above steps are the necessary steps for the detection of aflatoxin by the immunoaffinity column-high-performance liquid phase method. If the gas-controlled operation frame is used, the affinity column can be well fixed and operated at a controlled flow rate, which is both efficient and capable. Minimize operational errors.
Chinese An Maike ToxinFast ® pneumatic operating frame having six controllable tributaries can effectively detect a plurality of samples simultaneously, is also applicable to
1ml and 3ml immunological affinity columns of various specifications.
Why use a photochemical derivative?
Due to its strong UV absorption and fluorescence-generating properties, Aspergillus flavus can be subjected to HPLC-ultraviolet or fluorescence detection, but at the same time, B 1 and G 1 in aflatoxin are prone to fluorescence quenching due to their presence in the aqueous mobile phase. Therefore, in many experiments, a derivative method is used to determine aflatoxin.
There are also many methods of derivatization: pre-column, post-column, in-line, pre-column derivatization is generally derived from trifluoroacetic acid (TFA), post-column derivatization is generally carried out by iodination or bromination, and online photochemical derivatization is used. The advantages of online derivative are discussed with you ( no need for any chemical reagents, no harm to personnel; no need for direct operation by personnel, avoiding errors; no need to worry about derivative liquid corrosion detector )
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