How to inactivate new coronavirus-types and functions of various disinfectants.

Views:64     Author:Site Editor     Publish Time: 2020-02-03      Origin:https://post.smzdm.com/p/a5kl4e27/?send_by=5060342220

TongJi Hospital Affiliated to TongJi Medical College of Huazhong University of Science and Technology (hereinafter referred to as "Tongji Hospital") on the 22nd released the "Quick Guide for the Diagnosis and Treatment of New Coronavirus Pneumonia" formulated by the expert group of the hospital. And diagnosis and treatment.

According to the research on SARS-CoV and MERS-CoV, the coronavirus is sensitive to heat. It can effectively inactivate the virus within 30 minutes at 56 , ether, 75% ethanol, chlorine-containing disinfectant, peracetic acid and chloroform. Chlorhexidine has not been effective in inactivating the virus.

 

1. Chlorine-containing disinfectant

All disinfectants that are soluble in water and produce hypochlorous acid are collectively referred to as chlorine-containing disinfectants. It is an ancient disinfectant, but it is still an excellent disinfectant to this day. Generally speaking, the available chlorine in the chlorine-containing disinfectant does not refer to the content of chlorine, but the oxidizing capacity of the disinfectant, which is equivalent to how much chlorine has the oxidizing capacity. The disinfectant is divided into chloramine-based organic chlorine and hypochlorous acid-based inorganic chlorine. The former has a slow bactericidal effect but stable performance, while the latter has a fast bactericidal effect but unstable performance.

 

Common disinfectant formulations:

Liquid chlorine with a chlorine content greater than 99.5% (V / V);

Bleaching powder: containing 25% of available chlorine (W / W);

Bleach powder: containing 80% of available chlorine (W / W);

 

Three in two, containing 56% of available chlorine (W / W);

Sodium hypochlorite, industrially prepared containing 10% of available chlorine (W / W);

Sodium dichloroisocyanurate, containing 60% of available chlorine (W / W);

Trichloroisocyanuric acid, containing 85-90% of available chlorine (W / W);

 

 Trisodium chloride phosphate, containing 2.6% of available chlorine (W / W).

Sterilization principle: The sterilization mechanism of chlorine-containing disinfectant has three points:

Hypochloric acid oxidation: Hypochlorous acid is a small neutral molecule, which can diffuse to the surface of negatively charged bacteria and penetrate through the cell wall to the inside of the bacteria to play an oxidizing role, which destroys the phosphate removal of bacteria Catalase, imbalance of sugar metabolism and bacterial death;

The role of new ecological oxygen, the decomposition of hypochlorous acid to form new ecological oxygen, oxidizing bacteria protein;

Chlorination. Chlorine combines with cell membrane proteins to form nitrogen and chlorine compounds, which interferes with cell metabolism and eventually causes the death of bacteria.

The main advantages and disadvantages:

advantage:

Broad bactericidal spectrum, rapid action and reliable sterilization effect;

Low toxicity;

Easy to use and inexpensive.

Cons:

Unstable, easy to lose effective chlorine;

It has a bleaching effect on the fabric;

Corrosive;

Easily affected by organic matter, pH, etc.

 

Bactericidal effects: It can usually kill bacteria, viruses, fungal spores and bacterial spores.

How to use Common disinfection methods include soaking, wiping, spraying and dry powder disinfection.

Soaking method: Put the items to be disinfected or sterilized in a container containing a chlorine-containing disinfectant solution, and cover it. For disinfection of bacterial propagule-contaminated articles, soak with disinfectant containing effective chlorine 200mg / L for more than 10 minutes; for disinfection of hepatitis virus and Mycobacterium tuberculosis-contaminated articles, soak for more than 30 minutes with disinfectant containing effective chlorine 2000mg / L; To disinfect bacterial spore-contaminated items, soak them in a disinfectant containing 2000 mg / L of effective chlorine for 30 minutes.

Wiping method: Use the wiping method to sterilize large items or other items that cannot be sterilized by soaking. Refer to the soaking method for the concentration and duration of the drug used for disinfection.

Spraying method: uniformly spray 1000mg / L disinfectant solution (wall surface: 200mL / m2; cement floor: 350mL / m2, soil floor, 1000mL / m2) on general contaminated surface for more than 30 minutes; For disinfection of Mycobacterium tuberculosis-contaminated surfaces, spray evenly with a disinfecting solution containing 2000 mg / L of effective chlorine (the spraying amount is the same as above) for more than 60 minutes.

Dry powder disinfection method: To disinfect fecal matter, use bleach powder and other chlorine-containing disinfectants at 1/5 of the amount of fecal matter. Stir it a little and stir for 2-6 hours. The dry powder is added to the sewage at a dosage of 50mg / L of effective chlorine and stirred evenly, and is discharged after 2 hours.

Factors affecting sterilization

 

A. Concentration and action time The general rule is that the higher the drug concentration, the longer the action time, the better the bactericidal effect. However, as the concentration of bleaching powder and tri-medicine increases, the pH value of the solution also rises, and sometimes it takes prolonged action time to sterilize;

B. The lower the pH value, the stronger the bactericidal effect. The bactericidal effect of chlorine-containing disinfectants mainly depends on the concentration of undecomposed hypochlorous acid in the solution, and the lower the pH value of the solution, the more undecomposed hypochlorous acid, and as the pH value increases, more and more hypochlorous acid Acid decomposes into hydrogen and hypochlorite ions without losing bactericidal effect;

C. Temperature Increasing temperature can strengthen the bactericidal effect. But do not heat the sodium hypochlorite solution, otherwise it will cause its decomposition and reduce the sterilization effect;

D. Organic matter The presence of organic matter can deplete the available chlorine and affect its bactericidal effect. The effect on the low-concentration disinfectant is obvious. The effect of starch, fat and alcohol is small (methanol has a synergistic effect on sodium hypochlorite), but organic matter has a smaller effect on sodium dichloroisocyanurate;

E. Reducing substances Reducing substances such as thiosulfate, ferrous salt, sulfide, and amino-containing compounds can also reduce their bactericidal effect. Pay attention when disinfecting sewage;

 

F. water hardness The hardness is less than 400mg / L, which has little effect on its sterilization effect.

 

6. precautions for use

It should be stored in a covered container and replaced in time;

Do not use for disinfection and sterilization of surgical instruments;

When soaking and disinfecting, do not bring too much moisture into the items;

Do not use for disinfection of the surface contaminated by blood, pus, feces and other organic matter. Before disinfecting the articles, remove the organic matter adhered to the surface;

Do not use for sterilization of surgical sutures;

When disinfecting textiles with chlorine disinfectant, rinse immediately with water after disinfection.


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