"Buy toothpaste, please pay attention to the color strip at the bottom of the toothpaste tube! Today, I know that the original color bar also has meaning. When buying, try to choose green and blue. Go back and check the color of the reverse side of your toothpaste tube. 4 kinds: green, blue, red, black. Green, pure natural; blue, natural + drug; red, natural + chemical composition; black, purification." This recently spread on the Internet, "toothpaste science", Many consumers have messed up. Some people immediately threw the toothpaste on the bottom of the house with black strips. They ran to the supermarket and opened the toothpaste box to see the color bars. After throwing away the black toothpaste that is being used, the citizen Tang Lei still does not trust: "I have used this toothpaste for many years, will it cause harm to the body?" Is the statement in "Toothpaste Science Press" accurate? Our reporter recently entered the Basic Research Laboratory for New Hazardous Chemicals Assessment and Accident Identification of the State Administration of Work Safety of the School of Science, Beijing University of Chemical Technology, and asked the researchers to verify. Experimental preparation: Purchase 5 color strip toothpaste The reporter purchased toothpastes of different color strips in three supermarkets. In addition to green, blue, red and black, the reporter also found white toothpaste that was not mentioned on the Internet. In the supermarket, blue strips and black strips of toothpaste are more common. Red strip toothpaste is mostly children's toothpaste. Green strip toothpaste is mostly made of drug toothpaste and bamboo salt toothpaste. White strip toothpaste is the least. The reporter found a dimension. C toothpaste. It seems that the bottom of the reverse side of the toothpaste tube does have different color bars. The online statement seems to have a certain degree of credibility. Experimental principle: Ion Chromatography Laboratory experimenter Wang Linan and Peng Zuomao designed and led the experiment. They told reporters that the focus of this experiment is to detect whether the toothpaste contains chemicals, the main detection direction is set to the most common fluoride ion concentration in toothpaste. "Fluorine can prevent dental caries, it is used in most toothpastes, and fluorine is a chemical. If fluoride is detected in all toothpaste samples, it at least proves that the green toothpaste on the Internet is pure natural. The statement is incorrect. It is not reliable to divide the toothpaste according to the color bar." Wang Linan said. Experimental steps: Five types of toothpaste for fluoride concentration The experimental staff Wang Linan used the five kinds of color toothpastes to weigh 200 mg each with a precision balance, and placed them in five centrifuge tubes marked with green, blue, red, black and white. Subsequently, Wang Linan added 40 ml of ultrapure water to each centrifuge tube. In order to reduce the error, he used a pipetting gun to extract 5 ml of ultrapure water each time and inject 40 ml of ultrapure water in 8 times. In order to fully dissolve the soluble substances in the toothpaste into ultrapure water, Wang Linan placed five centrifuge tubes containing toothpaste and ultrapure water in a centrifuge for centrifugation and added a centrifuge containing only ultrapure water. The tube keeps the centrifuge running. After the centrifuge was run at 2000 rpm for 10 minutes, the experimenter took out the centrifuge tube. Next, you need to make a sample. The experimenter used a disposable needle tube equipped with a microporous membrane at the front end, and extracted 6 ml of the upper layer from each centrifuge tube, and the larger particles were filtered by the microporous membrane. Finally, the 6 tubes containing the sample were placed in an ion chromatograph autosampler, waiting for the fluoride ion concentration detection results of 6 samples. Experimental results: 5 toothpastes contain chemicals After an hour, a detection map appeared on the computer. Peng Zuomao and Wang Linan analysis results: fluoride ions were detected in all toothpaste samples. From the concentration point of view, the concentration of fluoride ion in green toothpaste and blue toothpaste solution is relatively low, only sixty to seventy milligrams per kilogram of toothpaste, red The concentration of fluoride ion in the toothpaste and black toothpaste solution is high, about 10 times that of the first two, while the concentration of fluoride ion in the white toothpaste solution is the highest, containing 914 mg of fluoride per kilogram of toothpaste. Fluoride ions were not detected in the blank contrasted ultrapure water. Therefore, the saying on the Internet that the use of color strips to select pure natural toothpaste is untenable. However, Wang Linan specifically stated that according to relevant national standards, the fluoride content of adult toothpaste should not exceed 0.15%, that is, the fluorine content per kilogram of toothpaste should not exceed 1500 mg; the fluoride content of children's toothpaste should not exceed 0.11%, that is, each The fluoride content of kilograms of toothpaste should not exceed 1100 mg. All toothpastes sent for inspection did not exceed national standards and were within safe limits. Cashmere Modal Scarf,Modal Wool Scarf,Modal Scarf,Plain Modal Wool Scarf INNER MONGOLIA CASHMERE PRODUCTS CO., LTD. , https://www.grpashmina.com