[Answer "epidemic" to solve confusion]

  ◎Our reporter Chen Xi

  Although sodium azide is contained in the sample extract of the COVID-19 antigen detection kit produced by some manufacturers in order to prevent corrosion, it is extremely harmful because it has been highly diluted and the content is very low.

Furthermore, there is no explosion hazard when sodium azide is in an aqueous state.

  ——Zhang Yan, Professor, School of Pharmacy, Tianjin University

  Take out the swab, collect the sample, immerse the sample into the test tube, take out the test card, drop the sample, read the result... The new crown antigen detection kit known as "test results can be obtained in 15 minutes" has received widespread attention since its inception .

  However, "people" are popular, and various rumors about it will appear on the Internet every once in a while.

It was the sampling swab that started to "get hit", and recently it was the turn of the sample extract.

  According to the Internet, "the extraction tube for antigen testing contains highly toxic sodium azide, which is easy to explode".

Although the public is very unfamiliar with sodium azide, the words "highly toxic" and "explosive" still make many people anxious.

They worry about the harm to the body after touching the liquid, and some people worry about the safety hazard when discarding the antigen test waste.

  "These statements are all alarmist." Zhang Yan, a professor at the School of Pharmacy of Tianjin University, said in an interview with a reporter from Science and Technology Daily that although some manufacturers have produced new crown antigen detection kit sample extracts that contain sodium azide in order to prevent corrosion, due to its It has been highly diluted and the content is very low, so the hazard is minimal.

Furthermore, there is no explosion hazard when sodium azide is in an aqueous state.

  Web-borne Substance is a Preservative

  "Most new crown antigen detection kits are mainly composed of three parts, namely sampling swab, sample extraction solution and sample extraction tube. In addition, the box will also contain instructions, test cards, biosafety bags, etc." Zhang Yan introduced , in which the function of the sample extract is to split the virus, so that the antigen is fully released.

  The components of various sample extracts are roughly the same, and generally contain biological buffer solutions, surfactants, purified water and preservatives.

Among them, the function of the biological buffer solution is to maintain the environmental conditions to ensure the integrity of the biologically active substances, that is, the integrity of the sampling sample.

The main function of surfactants is to lyse viruses to release antigens.

  "In order to ensure that the sample extract can be stored for a long time without deterioration, manufacturers will add preservatives to it, and sodium azide is one of the preservatives." Zhang Yan introduced that sodium azide is also known as three Sodium nitride, an inorganic compound, does have some toxicity, but when it is added to the sample extract, it is highly diluted, so the level is very low.

If this solution accidentally comes into contact with skin or eyes, rinse immediately with plenty of water.

  Although sodium azide is not flammable, it is explosive.

Sodium azide in solid form can decompose and explode at temperatures above its melting point or under severe vibration.

There is also an explosion hazard when it forms azides with metals, acids and chlorinated solvents.

"But in the extraction tube of the new crown antigen detection, sodium azide is in an aqueous state, and there is no risk of explosion at this time." Zhang Yan said.

  Pay attention to proper handling and proper disposal

  Zhang Yan introduced that the use details of the new crown antigen detection kits produced by different manufacturers will be slightly different, but they are generally the same, and the basic process is "three steps"——

  The first step is to prepare for the self-test.

Wash your hands with running water or disinfectant first, then carefully read the instruction manual of the antigen detection reagent and the precautions related to antigen detection, check whether the antigen detection reagent is within the shelf life, and check whether the contents such as the nasal swab are missing or damaged. Expired or missing reagent contents should be replaced in time.

Finally, during the detection process, the indoor temperature needs to be kept between 14 and 30 degrees Celsius, and the product storage temperature should be between 2 and 30 degrees Celsius.

  The second step of sample collection.

Blow your nose with toilet paper, tilt your head slightly, and then unpack the nasal swab, but avoid touching the swab head with your hands.

At this time, pay special attention to entering the swab with the tail of the swab in one hand and sticking to the side of the nostril, along the bottom of the lower nasal passage, and slowly go back 1 to 1.5 cm, and then rotate it at least 4 times in the nasal cavity (the residence time is not less than 15 seconds) .

Subsequently, the same procedure is repeated for the other nasal cavity using the same swab.

Those over 14 years old can perform nasal swab sampling by themselves; those aged 2 to 14 years old should be sampled by an adult.

  The third step is antigen detection.

Put the nasal swab after collecting the sample into the sampling tube immediately, rotate the swab head in the sample extraction solution for at least 30 seconds, and squeeze the swab head at least 5 times across the outer wall of the sampling tube.

After the liquid from the swab head is squeezed dry, the swab is discarded.

After capping the sampling tube, drop the liquid vertically into the sample hole of the test card.

Finally, wait for 15 minutes to observe and display the results, and use a mobile phone to take pictures and save them in time. The results displayed after 30 minutes have no clinical significance.

  For waste disposal, whether the antigen test results of the quarantine observers are negative or positive, all tested items after use must be put into biosafety bags, sealed and handed over to professional managers for processing.

For non-isolated observers, if the antigen test result is negative, the test items can be put into a sealed bag and disposed of as general garbage; if the antigen test result is positive, the used sampling tubes, test cards and other items should be removed. It is handed over to medical institutions for disposal as medical waste when people are transported.

  Zhang Yan reminded the public that when using the new crown antigen detection kit, they must strictly follow the steps indicated in the instructions.

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