Nitrite test paper

Beijing Huakesheng Fine Chemical Products Trading Co., Ltd. produces and sellsNitrite test paper:<span background-color:#f5f5f5; '='' style='padding: 0px; margin: 0px; list-style: none; font-family: 'Noto Sans SC'; color: rgb(51, 51, 51); Citric acid (CA), also known as citric acid, has the molecular formula C? H? O?, It is an important organic weak acid, which is a colorless crystal, odorless, easily soluble in water, and has an acidic solution. In biochemistry, it is an intermediate in the citric acid cycle (tricarboxylic acid cycle), which occurs in all aerobic organisms. Citric acid is widely used as an acidity regulator (GB27602014), flavoring agent, and chelating agent.

Nitrite test paperPrinciple: Under hydrochloric acid acidification conditions, nitrite undergoes diazotization reaction with p-aminobenzenesulfonic acid, and then combines with N-1-naphthalenedioic acid hydrochloride to form a rose red dye. By visually comparing the sample after color reaction with a standard color solution of known concentration, the nitrite content in food can be estimated. Operation: 1. Prepare a 4mg/mL solution of p-aminobenzenesulfonic acid: Weigh 0.4g of p-aminobenzenesulfonic acid and dissolve it in 100mL of hydrochloric acid with a mass fraction of 20%. Store in the dark. N-1-naphthylethylenediamine hydrochloride solution with a mass concentration of 2mg/mL: Weigh 0.2g of N-1-naphthylethylenediamine hydrochloride and dissolve it in 100mL of water. Store in the dark. Sodium nitrite solution with a mass concentration of 5 μ g/mL: Weigh 0.10g of sodium nitrite dried in a silica gel dryer for 24 hours, dissolve it in water and make up to 500mL, then transfer 5mL of the solution to a 200mL volumetric flask and make up to 200mL. Extraction agent: Weigh 50g of cadmium chloride and 50g of barium chloride, dissolve them in 1000mL of distilled water, and adjust the pH to 1 with concentrated hydrochloric acid. The concentration of aluminum hydroxide lotion and substance is 2.5 mol/L * solution. 2. Prepare standard colorimetric solution by pipetting 0.20mL, 0.40mL, 0.60mL, 0.80mL, 1.00mL, and 1.50mL of sodium nitrite solution (equivalent to 1ug, 2 μ g, 3 μ g, 4 μ g, 5 μ g, and 7.5 μ g of sodium nitrite) into 50mL colorimetric tubes, and then take another colorimetric tube as a blank control. Add 2.0mL of p-aminobenzenesulfonic acid solution to each tube, mix well, let it stand for 3-5 minutes, then add 1.0mL of N-1-naphthylethylenediamine hydrochloride solution to each tube, add distilled water to make the total volume inside each colorimetric tube 50mL, mix well, and observe the gradient change in color of the sodium nitrite solution.