GB/T 5413.24-1997National food safety standard -- Determination of chlorine in foods for infants and young children, milk and milk products (English PDF)
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Issued by
Ministry of Health of the People's Republic of China
Level / Type
National · Recommended
Issue date
March 26, 2010
Implementation date
June 1, 2010
Scope
GB/T 5413.24-1997 (National food safety standard -- Determination of chlorine in foods for infants and young children, milk and milk products) is available as an English-translated PDF.
GB/T 5413.24-1997 — This standard specifies the infant food and dairy products Determination of chlorine. This standard applies to food and dairy products Determination of chlorine in infants.
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Document preview — GB/T 5413.24-1997
National Standard of the People's Republic of China
- ICS
- 67.100.10
- Classification
- C 53;X82
- Replacing
- GB/T 5413.24-1997
Issued by: Ministry of Health of the People's Republic of China
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 4 Reagents and materials
- 4.8 Protein precipitant
- 4.11 Standard silver nitrate titration solution (0.02 mol/L)
- 5 Apparatus
- 6 Step, Analysis
- 6.1 Preparation of test solution
- 6.2 Analysis Steps
- 7 Expression analysis
- 7.1 Calculation Results
- 8 Precision
- 10 Reagents and materials
- 11 Instruments and equipment
- 12 Analysis steps
- 13 Analysis results presentation
- 14 Precision
Foreword
This standard replaces GB/T 5413.24-1997 "infant formula and milk powder - Determination of chlorine." this standard replaces the standards previously issued as follows.
--GB 5413-1985, GB/T 5413.24-1997.
National Food Safety Standard Determination of infant foods and dairy products of chlorine
1 Scope
This standard specifies the infant food and dairy products Determination of chlorine.
This standard applies to food and dairy products Determination of chlorine in infants.
2 Normative references
The standard file referenced in the application of this standard is essential. For dated references, only the edition date of the note Apply to this standard. For undated references, the latest edition (including any amendments) applies to this standard.
The first potentiometric titration method Principle 3 Samples treated by acidification, acetone was added to the glass electrode as the reference electrode, silver electrode as indicator electrode with standard silver nitrate titration solution Titration test solution of chloride ions, according to the potential of the "jump" to determine the titration end point. Press the consumption standard silver nitrate titration solution, calculation test the chlorine content of the sample.
4 Reagents and materials
Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provisions of secondary water.
4.1 potassium ferrocyanide (K4Fe (CN) 6 - 3H2O).
4.2 zinc acetate (Zn (CH3CO2) 2).
4.3 Glacial acetic acid (CH3COOH).
4.4 nitric acid (HNO3).
4.5 acetone (C3H6O).
Sodium chloride 4.6 standard (NaCl).
4.7 standard silver nitrate (AgNO3).
4.8 Protein precipitant
4.8.1 precipitant I. Weigh 106 g of potassium ferrocyanide (4.1), dissolved in water and transferred to a 1000 mL volumetric flask, dilute with water to Scale.
4.8.2 precipitant II. Weigh 220 g zinc acetate (4.2), dissolved in water and added to 30 mL of glacial acetic acid (4.3), transfer to a 1000 mL Volumetric flask, dilute to the mark.
4.9 nitric acid solution (13). 1 by volume nitric acid (4.4) with 3 volumes of water and mix.
4.10 sodium chloride standard solution (0.01 mol/L). Weigh 0.5844 g after 500 °C ± 50 °C drying to constant weight sodium chloride standard (4.6), in 100 mL beaker with a small amount of water dissolved and transferred to a 1000 mL volumetric flask, dilute to the mark.
4.11 Standard silver nitrate titration solution (0.02 mol/L)
4.11.1 preparation. Weigh 3.40 g (accurate to 0.01 g) of silver nitrate standard (4.7), in 100 mL beaker with a small amount of water to dissolve After the transfer to a 1000 mL volumetric flask with water to volume, shake, dark storage, or transferred to a brown volumetric flask.
4.11.2 Calibration (second derivative). lessons 10.00 mL sodium chloride standard solution (4.10) in 50 mL beaker, was added 0.2 mL Nitric acid (4.4) and 25 mL of acetone (4.5). The glass electrode and a silver electrode immersed in the solution, start the magnetic stirrer.
V dropped ml standard silver nitrate titration solution (90% of the required amount) from the burette, the solution was measured potential value (E). Continue to trickle Standard silver nitrate titration solution, each solution was measured immediately dropped 1 mL potential value (E). Close to the end and after the end of each solution of 0.1 mL Solution potential measured value (E). Continue to trickle standard silver nitrate titration solution until the solution is no longer the potential value change significantly. Table 1 Example Format recording volume value and potential value of the standard silver nitrate titration solution per instillation.
4.11.3 titration end point is determined. according to titration record (4.11.2), by volume, value (V) standard silver nitrate titration solution and the potential Value (E), by way of the list in Table 1 illustrates the calculation of deltaE, deltaV, a derivative and secondary derivative value included in the table.
Example 1 table records the standard silver nitrate titration solution of sodium chloride standard solution titration VE deltaEa deltaVb first derivative (deltaE/deltaV) two derivative 400 0.00 70 18 4.00 470 4.00 twenty two 20 0.5 40 4.50 49060 10 100 0.1 4.60 50050 15 0.1 150 4.70 51550 20 200 0.1 4.80 535 650 85 0.1 850 4.90 620-350 50 500 0.1 5.00 670-300 20 200 0.1 5.10 690-100 10 100 0.1 5.20 700 - - - -Potential changes in the value of a corresponding.
b continuous trickle standard silver nitrate titration solution volume increase value.
Potential changes in the value of c per unit volume of standard silver nitrate titration solution caused that deltaE and deltaV ratio.
d difference values of adjacent first derivative equivalent.
When the first derivative maximum, when two derivative equal to zero, is the titration end point, when according to formula (1) calculate the standard silver nitrate titration endpoint titration solution Volume (V1) solution.
)delta- = Vba
aVV a1 (1)
Where.
1V - value consumed titration end point standard silver nitrate titration solution volume in milliliters (mL);
aV - consumption volume of the standard silver nitrate titration solution at a time, in milliliters (mL);
a-- two two derivative zero before;
b-- two two derivative value is zero after;
Numerical Vdelta --a and b, in milliliters (mL).
Example.
Find the first derivative maximum value from the table 850, the secondary derivative equal to zero should be between 650 and -350, so a = 650, b =-350, V = 4.8 mL, Vdelta = 0.10mL.
() 87.4065.08.410.0350650 6508.41 = = ]] ][[ [ × - = ((())))delta- = Vba aVV a (mL) that is when the titration end point, the amount of the standard silver nitrate titration solution of 4.87 mL.
(2) Calculation 4.11.4 standard silver nitrate titration solution concentration according to the formula.
10cc
Where.
The exact value of c2-- standard silver nitrate titration solution, expressed in moles per liter (mol/L);
C1-- exact concentration of sodium chloride solution reference value, in units of moles per liter (mol/L);
Numerical consumed V1-- titration end point standard silver nitrate titration solution volume in milliliters (mL).
5 Apparatus
5.1 pH meter. accuracy of 0.1.
5.2 glass electrode.
5.3 silver electrode.
5.4 magnetic stirrer.
5.5 Burette. 10 mL.
5.6 Balance. a sense of the amount of 0.1 mg, 1 mg.
6 Step, Analysis
6.1 Preparation of test solution
Weigh about 20 g (accurate to 0.001 g) sample in 250 mL conical flask, 100 mL70 °C hot water after boiling for 15 min, and continue to shake. Remove, cool to room temperature, followed by adding 4 mL precipitant I (4.8.1) and 4 mL precipitant II (4.8.2). Each After adding fully shake at room temperature for 30 min. The Erlenmeyer flask contents were all transferred to 200 mL volumetric flask, dilute with water to Mark and shake. Filtered with filter paper, discard the first portion of the filtrate.
6.2 Analysis Steps
10 mL of test solution (6.1), in 50 mL beaker, add 5 mL solution of nitric acid (13) (4.9) and 25 mL of acetone (4.5).
The following steps in section 4.11.2, 4.11.4 calculated according to consumption at the end of the titration to the standard silver nitrate titration solution volume value (V2).
7 Expression analysis
7.1 Calculation Results
The chlorine content in the sample to the mass fraction X1 and its value is expressed in milligrams per hundred grams (mg/100 g) said, according to the formula (3) Calculated.
1005.35
twenty two
fVcX (3)
Where.
X1-- chlorine content of the sample, the unit is milligram per hundred grams (mg/100 g);
35.5-- and 1.00 mL standard silver nitrate titration solution [c (AgNO3) = 1.000 mol/L] equivalent to the chlorine value in mg (Mg);
Volume consumed V2-- titration sample standard silver nitrate titration solution in milliliters (mL);
f-- dilution;
m1-- sample mass, in grams (g);
The exact value of c2-- standard silver nitrate titration solution, expressed in moles per liter (mol/L).
7.2 The results are shown the arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures.
8 Precision
The absolute difference between two independent test results obtained under repeatability conditions does not exceed 5% of the arithmetic mean.
The second method precipitation titration Principle 9 Organic acids precipitated proteins in the sample with a solution of silver nitrate titration of chloride ions in the sample, generate precipitation of silver chloride; excess silver nitrate and potassium chromate indicator reaction solution was made of silver chromate is orange titration end. Chlorine in the sample is calculated from the consumption of silver nitrate solution content.
10 Reagents and materials
Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provisions tertiary water.
10.1 Sodium hydroxide (NaOH).
10.2 Potassium chromate (K2CrO4).
10.3 sodium chloride standard (NaCl). purity >=99%.
10.4 silver nitrate (AgNO3).
10.5 trichloroacetic acid solution (500 g/L). Weigh 500 g of trichloroacetic acid dissolved in 1000 mL of water.
10.6 sodium hydroxide solution (50 g/L). Weigh 25g sodium hydroxide dissolved in 500 mL of water.
10.7 nitric acid solution (0.1 mol/L). draw 6 mL of nitric acid, dilute with water to 1000 mL.
10.8 potassium chromate solution (50 g/L). Weigh 5 g of potassium chromate was dissolved in 100 mL of water.
10.9 sodium chloride standard solution (0.1 mol/L). says learn 500 °C ± 50 °C drying to constant weight of 5.8440 g sodium chloride standard in 1000 mL volumetric flask, and dissolved in deionized water to volume.
10.10 silver nitrate solution (0.05 mol/L). Weigh 8.50 g (accurate to 0.01 g) of silver nitrate standard (10.4), in 100 mL burn Cup with a small amount of water transferred to a 1000 mL volumetric flask and dissolved in water to volume, shake, dark storage, or transfer to a volumetric flask brown in.
10 mL of sodium chloride standard solution (10.9) to 125 mL volumetric flask, add 10 drops of potassium chromate solution (10.8), the above-mentioned nitric acid Silver solution titration, according to the volume of silver nitrate solution consumed, according to (4) to calculate the actual concentration of silver nitrate solution.
c 101.0 × = (4)
Where.
C-- actual concentration of silver nitrate solution, expressed in moles per liter (mol/L);
V-- volume of silver nitrate solution, in milliliters (mL);
0.1-- concentration of sodium chloride standard solution, unit mole per liter (mol/L);
Volume 10-- sodium chloride standard solution, in milliliters (mL).
10.11 phenolphthalein indicator ethanol (10 g/L). Weigh 1 g phenolphthalein dissolved in 100 mL of ethanol (95%).
11 Instruments and equipment
11.1 balance. a sense of the amount of 0.1 mg.
11.2 flasks. 100 mL.
11.3 flasks. 125 mL.
11.4 Brown Buret. 10 mL.
12 Analysis steps
12.1 Weigh mixed sample 10 g (accurate to 0.0001 g) in a small beaker, add 50 mL of water and dissolved moved into 100 mL capacity Bottle, add trichloroacetic acid solution (10.5) 10 mL volume and mix and let stand for about 1 min and filtered.
12.2 draw filtrate 10 mL to 125 mL Erlenmeyer flask, add three drops of phenolphthalein (10.11), (10.6) adjusted with sodium hydroxide solution Section to reddish. Callback with nitric acid solution (10.7) to the red just receded. Plus 10 drops of potassium chromate solution (10.8) after silver nitrate solution (10.10) titration to orange within 1 min does not fade, it is the end, when the titration put a white paper at the bottom, and more easy to identify the end. with when the blank test.
13 Analysis results presentation
The chlorine content of the sample according to equation (5) Calculated.
X2 = () 53 4 3
10035.5 VV V c
Where.
X2-- chlorine content of the sample, the unit is milligram per hundred grams (mg/100 g);
V3 - the volume of the titration sample solution consumed silver nitrate solution, in milliliters (mL of);
V4-- blank solution volume consumed by the silver nitrate solution, in milliliters (mL);
c3 - the concentration of silver nitrate solution, expressed in moles per liter (mol/L);
V5-- sample solution volume in milliliters (mL of);
V6-- draw filtrate volume in milliliters (mL);
m2 - mass of the sample in grams (g).
The arithmetic mean of two under the same condition of independent determination results indicated that the results to two significant figures.
14 Precision
The absolute difference between two independent test results obtained under repeatability conditions does not exceed 5% of the arithmetic mean.
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