Rapid on-site detection of nitrite
（Instructions for use of nitrite rapid measuring tube）
1. Scope of application: this rapid measuring tube is suitable for rapid identification of nitrite and rapid determination of nitrite content in food or water. Detection limit: 0.05mg/l. Linear range: 0.05 ~ 5.0 mg / L.
2. Rapid detection of nitrite in table salt and rapid identification of table salt and nitrite: Take 1 flat spoon of table salt with a small spoon attached to the bag, add it to the detection tube, add distilled water or purified water to the 1ml scale, cover the cover, shake the solid part, and compare it with the standard color plate after 10 minutes. The value on the color plate multiplied by 10 is the content of nitrite in table salt, mg / kg. When the sample appears blood red and precipitates or quickly fades to yellow, it can be determined that the nitrite content is quite high, or the sample itself is nitrite.
3. Liquid sample detection: directly add 1ml of clarified liquid sample into the detection tube, cover the cover, shake and dissolve the reagent, compare it with the standard color plate after 10 minutes, and find out the color scale that is the same as the color of the solution in the detection tube. The value on the color scale is the content of nitrite (calculated as NaNO2) in the sample, mg / L. If the content of nitrite is calculated in nitrogen (n) (such as drinking water or source water), read the value on the color scale and divide it by 5. If the content of nitrite is calculated by nitrite (NO2 -) (such as mineral water, bottled purified drinking water, etc.), read the value on the color scale and divide it by 3.28.
4. Detection of turbid sample: 1ml of milk and bean paddle can be directly added to the detection tube, cover it, shake and dissolve the reagent, compare it with the standard color plate after 10 minutes, and find out the color scale that is the same as the color of the solution in the detection tube. The value on the color scale multiplied by 2 is the approximate content of nitrite in the sample, mg / L.
5. Detection of solid or semi-solid samples: take 1.0g or 1.0ml to 10ml of uniformly crushed sample into the colorimetric tube, add distilled water or deionized water (purified water) to the scale, shake it sufficiently and place it. Take 1.0ml of supernatant (or supernatant obtained by filtration or centrifugation) and add it into the detection tube, cover it, shake and dissolve the reagent, and compare it with the standard color plate after 10 minutes. The value on the color plate multiplied by 10 is the content of nitrite in the sample, mg / kg, L (calculated as NaNO2). If the test result exceeds the maximum value on the color plate, it can be measured after quantitative dilution and multiplied by the dilution multiple when calculating the result (for example, take 1.0ml from 10ml colorimetric tube and transfer it to another 10ml colorimetric tube, add water to the scale, and add 1.0ml from it to the detection tube for determination. The test result multiplied by 100 (dilution multiple) is the content of nitrite in the sample.
6.1 when the nitrite content is high, the reagent will turn yellow soon after it turns red. Dilute the yellow solution and put it into another new rapid test tube, it will turn red again, so as to distinguish between nitrite and edible salt.
6.2 when the color of the sample after reaction is greater than the 2.00mg/l color scale of the standard color plate, the sample shall be diluted and then measured, and the dilution multiple shall be multiplied when calculating the result.
6.3 nitrite often exists in domestic drinking water and should not be used as diluent for determination.
6.4 the reagent shall be stored at room temperature and away from light, and the validity period is 24 months.
1. 适用范围：本速测管适用于亚硝酸盐的快速辨别及食物或水中亚硝酸盐含量的快速测定。检出限：0.05mg/L。线性范围：0.05～5.0 mg/L。
2. 食盐中亚硝酸盐的快速检测及食盐与亚硝酸盐的快速鉴别：用袋内附带小勺取食盐1平勺，加入到检测管中，加入蒸馏水或纯净水至1ml刻度处，盖上盖，将固体部分摇溶，10分钟后与标准色板对比，该色板上的数值乘上10即为食盐中亚硝酸盐的含量mg/ kg，（国标规定食盐（精盐）中亚硝酸盐的限量卫生标准应≤2 mg/kg）。当样品出现血红色且有沉淀产生或很快退色变成黄色时，可判定亚硝酸盐含量相当高，或样品本身就是亚硝酸盐。
以N-计： 生活饮用水 ≤1mg/L（约为≤5mg/L NaNO2 ）
以NO2-计： 矿泉水≤0.1 mg/L （约为≤0.15mg/L NaNO2 ）；
包装饮用水以≤0.005 mg/L（约为≤0.008mg/L NaNO2 ）
图像1. 水中的亚硝酸盐 图像2.牛乳中的亚硝酸盐