This standard specifies the determination method of chlorine. This standard is applicable to the determination of chlorine in infant formula and milk powder. GB/T 5413.24-1997 Determination of chlorine in infant formula and milk powder GB/T5413.24-1997 Standard download decompression password: www.bzxz.net

GB/T5413.24—1997
This standard provides two methods. Method 1 is to adopt the method in Chapter 3 of GB/T12457-90 "Determination of Sodium Chloride in Food". Method 2 is the potassium chromate indicator method.
This series of standards will replace GB5413-85 from the date of implementation. This standard is proposed by the China Light Industry Federation.
This standard is under the jurisdiction of the National Dairy Standardization Center. The responsible drafting unit of this standard: National Dairy Quality Supervision and Inspection Center. Participating drafting units of this standard: Food Hygiene Supervision and Inspection Institute of the Ministry of Health, Zhejiang Light Industry Research Institute, Harbin Morinaga Dairy Co., Ltd., Nestle (China) Investment Service Co., Ltd. The main drafters of this standard: Wang Yun, Jiang Jindou, Shuai Shuo, Tian Jian. 319
National Standard of the People's Republic of China
Infant formula and milk powder
Determination of chlorine
Milk powder and formula foods for infant and young children-Determination of chlorine
This standard specifies the determination method of chlorine.
This standard applies to the determination of nitrogen in infant formula and milk powder. 2 Referenced standards
GB/T5413.24--1997
Replaces GB5413-85
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T12457-90 Determination of sodium chloride in food Method-Potentiometric titration
Same as Chapter 3 of GB/T12457--90.
Method Potassium dichromate indicator method
3 Method summary
Organic acid precipitates the protein in the sample, and the chloride ions in the sample are titrated with silver nitrate solution to generate silver chloride precipitation. The excess silver nitrate reacts with the indicator potassium chromate to generate silver chromate, which makes the solution orange-red, which is the titration end point. The chlorine content in the sample is calculated from the consumption of silver nitrate solution.
4 Reagents
All reagents, if the specifications are not specified, are analytically pure. All experimental water, if no other requirements are specified, refers to grade tertiary water. 4.1 Trichloroacetic acid solution: 500g/L.
4.2 Standard sodium fluoride solution: c(NaCl) is 0.1mol/L. Accurately weigh 5.8440g of sodium chloride dried (130℃) for 2h in a 1000mL volumetric flask, dissolve and make up to volume with deionized water. 4.3 Potassium chromate solution: c(KCrO,) is 50g/L, used as indicator. 4.4 Silver nitrate solution: c(AgNO.) is 0.05mol/L. Calibration: Take 10mL of standard sodium fluoride solution (4.2) in a 125mL volumetric flask, add 10 drops of potassium chromate indicator (4.3), titrate with the above silver nitrate solution, and calculate the actual concentration of the silver nitrate solution based on the volume of silver nitrate solution consumed. 4.5 Sodium hydroxide solution: c(NaOH) 50g/L. 4.6 Phenol butter ethanol indicator: 10g/L ethanol. Approved by Guohao Technical Supervision Bureau on May 28, 1997 320
Implemented on September 1, 1998
4.7 Nitric acid solution: c(HNO,) 0.1mol/L. 5 InstrumentsbZxz.net
Common laboratory instruments and:
5.1 Analytical balance.
5.2 Volumetric flask, 100mL.
5.3 Erlenmeyer flask, 125mL.
5.4 Brown burette, 10mL.
6 Operation steps
GB/T 5413. 24--1997
6.1 Accurately weigh 10.0000g of sample into a small beaker, add 50mL of water to dissolve, then transfer to a 100mL volumetric flask (5.2), add 10mL of trichloroacetic acid solution (4.1), mix well and make up to volume, let stand for about 1min and filter. 6.2 Pipette 10mL of filtrate into a 125mL Erlenmeyer flask (5.3), add three drops of phenol anhydride indicator (4.6), and adjust to a slightly reddish color with sodium hydroxide solution (4.5). Adjust to red with nitric acid solution (4.7) until the red color just fades. Add 10 drops of potassium chromate indicator (4.3) and then titrate with silver nitrate solution (4.4) until the orange color does not fade within 1 minute. This is the end point. Place a piece of yellow paper at the bottom during titration to make it easier to identify the end point. Perform a blank test at the same time.
7 Expression of analysis results
Chlorine content in sample (mg/100g) (VV.)×c×35.5×Where: V—Volume of silver nitrate solution consumed by titrating sample solution, mL, V.
Volume of silver nitrate solution consumed by blank solution, mL; -Concentration of silver nitrate solution, mol/L;
V,—Volume of sample solution, mL;
V2--—Volume of filtrate absorbed, mL
Mass of sample, g.
Calculate the result to the second decimal place. 8 Allowable plasticity
The difference between two measured values ​​of the same sample shall not exceed 5% of the average value of the two measurements. V
（4）
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