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Introduction to test paper for residual chlorine in water

by:BOQU     2023-03-29
【Introduction】Chlorine-containing preparations are the earliest and most widely used drinking water disinfectants, which are of great significance to the implementation of disinfection and to ensure the disinfection effect. The available chlorine in drinking water chlorine preparation is a method to characterize the oxidation ability of chlorine-containing disinfectant with chlorine gas as the standard. The higher the effective chlorine content in the disinfectant, the stronger the disinfection ability and the more thorough the killing of microorganisms. Residual chlorine refers to the residual chlorine content in water after the disinfectant has been used for a certain period of time. After the water is chlorinated and disinfected, if sufficient residual chlorine is maintained, it means that not only the disinfection effect is reliable, but also the disinfection effect is continuous. This speed test paper is a broad-spectrum chlorine detection test paper, which is used to judge whether the effective chlorine content in the disinfectant solution reaches the disinfection application value, whether the residual chlorine content in the water can ensure the disinfection effect, and whether the concentration is too high to affect the sensory properties of the water or even cause Secondary chemical pollution. [Detection principle] This quick test box uses the principle of visual colorimetry for semi-quantitative detection. The drug block on the test paper is in contact with the sample for color reaction, and the content of available chlorine and residual chlorine in the sample is determined according to the color of the test paper. Attached is the Hygienic Standards for Catering Industry and Collective Dining Distribution Units (Wei Jianfa [2005] No. 260) Supplementary 'Technical Specifications for Hygienic Quality of Bleach Powder and Bleaching Powder Disinfectants (Trial)', the concentration and use of disinfectants. [Testing steps] 1. Determination of available chlorine in disinfectant solution: Remove 1ml of the venom sample, add 4ml of water, shake well (the dilution factor is 5), soak all the test paper pieces in the sample solution and take them out immediately, wipe off the excess liquid on the edge of the test paper, and place the test paper pieces facing Place it horizontally, compare it with the color card in 40 seconds, and read the result. When the color of the test paper is too dark to exceed the range of the color card, the sample can be diluted and measured; 2. Determination of residual chlorine in water: take an appropriate amount of sample in a clean and dry container, immerse the test paper block in the sample solution and take it out immediately, wipe off the excess chlorine on the edge of the test paper. For liquid, put the test paper block upwards and place it horizontally, compare it with the color card in 40 seconds, and read the result. [Result Judgment] 1. The concentration of available chlorine in the diluted sample is equal to the reading value of the colorimetric card multiplied by the dilution factor, and the concentration of residual chlorine in water is equal to the reading value of the colorimetric card; 2. Comparing the detected value with the above standard, the concentration of available chlorine The value greater than or equal to the required value of the corresponding disinfection object is qualified, and the value less than the required value is unqualified; the domestic drinking water meets the requirements of GB/T 5750.11-2006 as qualified, and the non-conformity is unqualified. 【Detection limit】5mg/L. [Notes] 1. The test paper is easily affected by moisture, light and heat, and the working environment temperature is required to be 15°C~35°C, and the relative humidity should be ≤75%. 2. Do not touch the reaction area of ​​the test paper with your hands, and do not take out the desiccant. The taken out test paper strips should be used immediately, and each test paper can only be used once. 3. This test paper is not suitable for the detection of available chlorine of chlorine dioxide. [Storage conditions and validity period] The test paper should be stored in a dry environment at room temperature and away from light, and should not be placed in the refrigerator. Valid for 12 months.
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