GB 25574-2010National food safety standards of food additives sodium hypochlorite (English PDF)

Foreword

Appendix A of this standard is a normative appendix.

National Food Safety Standard Food additive sodium hypochlorite

1 Scope

This standard applies to food additives, sodium hydroxide and chlorine reaction of food additive sodium hypochlorite.

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.

3 Formula and relative molecular mass

Formula 3.1

NaClO

4 Technical Requirements

4.1 Sensory requirements. comply with Table 1.

Table 1 Sensory requirements

Project requires test methods Color colorless or pale yellow proper amount of sample placed in 50mL plastic beaker, Natural light to observe the color and texture. Liquid state organization

4.2 Physical indicators. to comply with Table 2.

Table 2. Physical and chemical indicators

Item Index Test Method Available chlorine (based on Cl), w /% >= 5.0 Appendix A A.4 the free base (NaOH in dollars), w /% 0.2 ~ 1.0 in Appendix A A.5 Iron (Fe)/(mg/kg) <= 50 Appendix A A.6 Heavy metals (Pb)/(mg/kg) <= 10 Appendix A A.7 Arsenic (As)/(mg/kg) <= 1 Appendix A A.8 Appendix A (Normative) Testing method A.1 Warning the standard test methods Reagents toxic or corrosive, the operation should be careful! As should be immediately washed with water splashed on the skin Wash, severe cases should be treated immediately.

A.2 General Provisions the standard test methods used in the reagents and water, did not indicate when the other requirements, refer to analytically pure reagents and GB/T 6682-2008 Three water regulations. Test with the standard titration solution, impurity standard solution, preparations and products, did not indicate when the other requirements, according GB/T 601, GB/T 602, GB/T 603 provisions of the preparation.

A.3 Identification Test A.3.1 Reagents and materials A.3.1.1 phosphate buffer solution. pH~8.0.

Solution I. Weigh 23.8g of anhydrous disodium hydrogen phosphate, dissolved in water and diluted to 1000mL;

Solution II. Weigh 9.07g potassium phosphate crystals, soluble in water, dilute to 1000mL;

The solution I II mixed solution of 50 parts and 7 parts, respectively, or a solution I II solution was adjusted to pH of the mixture was about 8.0.

A.3.1.2 litmus paper.

A.3.2 Identification method A.3.2.1 The samples with sodium hypochlorite reaction and response.

A.3.2.2 amount of 1mL sample was diluted with water to 25mL. 4mL amount of the above test solution was added 100mL of phosphate buffer solution, the Solution has maximum absorption at a wavelength of 291nm ~ 294nm place.

A.3.2.3 The samples were immersed in red litmus paper turns blue when litmus paper, then fade.

A.4 Determination of available chlorine A.4.1 Method summary in acidic medium, hypochlorite and potassium iodide, iodine deposited in starch indicator solution, and the solution with sodium thiosulfate standard titration drops Set to disappear as the blue end. Reaction is as follows.

2H ClO- 2I- = I2 Cl- H2O I2 2S2O32- = S4O62 - 2I-A.4.2 Reagents and materials A.4.2.1 potassium iodide solution. 100g/L.

A.4.2.2 sulfuric acid solution. 3 + 100.

A.4.2.3 sodium thiosulfate standard titration solution. c (Na2S2O3) = 0.1mol/L.

A.4.2.4 starch indicator solution. 10g/L.

A.4.3 Analysis step

A.4.3.1 Preparation of sample solution Weighed approximately 20mL sample, placed in a built about 20mL of water and has weighed (accurate to 0.01g) in 100mL beaker, weighed (accurate to 0.01g), then all moved into 500mL volumetric flask, dilute to the mark, shake. This solution as the test solution A, containing active chlorine for Amount, determination of free alkali content, iron content, heavy metals, arsenic content.

A.4.3.2 Determination Pipette 10.00mL sample solution A, placed in a built 50mL water 250mL iodometric flask, 10mL and 10mL sulfuric acid solution of potassium iodide Solution quickly after the stopper seal tightly, allowed to stand in the dark for 5min. Standard titration with sodium thiosulfate solution titration to pale yellow, add 2mL starch Indicator solution and continue titration to the disappearance of the blue is the end.

A.4.4 Calculation Results Chlorine content of chlorine (Cl) mass fraction w1 and its value is expressed in%, according to formula (A.1) Calculated.

() 050 010

cMVw (A.1)

Where.

Accurate c- sodium thiosulfate standard titration solution concentration value in units of moles per liter (mol/L);

Numerical sodium thiosulfate standard titration V- titration solution consumed volume in milliliters (mL);

Quality m1- sample value in units of grams (g);

M1- value chlorine (Cl) molar mass of the units of grams per mole (g/mol) (M1 = 35.453).

Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 0.2%.

A.5 Determination of the free base A.5.1 Method summary Hypochlorite decomposition of hydrogen peroxide, as phenolphthalein indicator solution, titration with hydrochloric acid standard solution titration to pale red to end. The reaction scheme under.

ClO- H2O2 = Cl- O2 H2O OH- H = H2O A.5.2 Reagents and materials A.5.2.1 hydrogen peroxide solution. 1 + 5.

A.5.2.2 hydrochloric acid standard titration solution. c (HCl) = 0.1mol/L.

A.5.2.3 phenolphthalein indicator solution. 10g/L.

A.5.2.4 starch - iodide test paper.

A.5.3 Analysis step

Pipette 50.00mL sample solution A, placed in 250mL Erlenmeyer flask, was added dropwise a solution of hydrogen peroxide to hypochlorous acid until the free (not to precipitate Powder - iodide test paper turns blue), add 2 drops to 3 drops of phenolphthalein indicator solution, titration with hydrochloric acid standard solution titration to pale red to end.

A.5.4 Calculation Results the free base with sodium hydroxide (NaOH) mass fraction w2 and its value is expressed in%, according to formula (A.2), said.

() 050 050

cMVw (A.2)

Where.

Accurate c- hydrochloric acid standard titration solution concentration value in units of moles per liter (mol/L);

Numerical hydrochloric acid standard titration solution consumed V- titration volume in milliliters (mL);

Quality m2- sample value in units of grams (g);

Numerical M2- sodium hydroxide (NaOH) molar mass in grams per mole (g/mol) (M2 = 40.00).

Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 0.04%.

A.6 Determination of iron A.6.1 Method summary in a medium free of hypochlorite, hydroxylamine hydrochloride to Fe3 reduced to Fe2, in pH4 ~ 4.5 buffer solution system, Fe2 with 1,10 Phen generated orange-red complex, the absorbance was measured with a spectrophotometer. Reaction is as follows.

4Fe3 NH2OH = 4Fe2 N2O H2O + 4H Fe2 3C12H8N2 = [Fe (C12H8N2) 3] 2 A.6.2 Reagents and materials A.6.2.1 hydrogen peroxide solution. 1 + 5.

A.6.2.2 acetic acid - sodium acetate buffer solution. pH~4.5.

A.6.2.3 hydroxylamine hydrochloride solution. 10g/L.

A.6.2.4 Weigh 1g of hydroxylamine hydrochloride, dissolved in water and diluted to 100mL.

A.6.2.5 iron standard solution. 1mL solution containing iron (Fe) 0.1mg.

A.6.2.6 iron standard solution. 1mL solution containing iron (Fe) 0.01mg.

Pipette 25.00mL iron standard solution (A.6.2.5), placed in 250mL flask, diluted with water to the mark. The solution was active Now equipped.

A.6.2.7 1,10- phenanthroline solution. 2g/L.

A.6.2.8 starch - iodide test paper.

A.6.3 Instruments and Equipment Spectrophotometer.

A.6.4 Analysis step

A.6.4.1 curve plotted A.6.4.1.1 Pipette iron standard solution (A.6.2.6) 0.00mL, 1.00mL, 2.00mL, 3.00mL, 4.00mL, 6.00mL, 8.00mL, 10.00mL were placed in eight 100mL flask, were added to each flask hydroxylamine hydrochloride solution 5mL, 10mL acetic acid - sodium acetate Dilution buffer and 5mL1,10- Phen solution to the mark with water, shake and let stand 10min.

A.6.4.1.2 without iron standard solution with the blank solution to adjust the zero spectrophotometer, at a wavelength of 510nm at the choice of the appropriate cuvette, Absorbance was measured.

A.6.4.1.3 to 100mL standard colorimetric solution iron content (mg) as abscissa and the corresponding absorbance vertical axis, the work Curve or linear regression equation.

A.6.4.2 blank test

Without the sample solution, using the same sample solution and measured analysis steps, and the amount of reagent blank test.

A.6.4.3 Determination Pipette 50.00mL sample solution A, placed in 100mL flask, a solution of hydrogen peroxide solution to free up hypochlorite (not to precipitate Powder - iodide test paper turns blue), then added hydroxylamine hydrochloride solution 5mL, 10mL acetic acid - sodium acetate buffer solution and 5mL1,10- phenanthroline solution, Diluted with water to the mark, shake and let stand 10min. The following were prescribed according to A.6.4.1.2.

A.6.5 Calculation Results Iron content of iron (Fe) mass fraction w3 and its value in mg/kg according to formula (A.3) Calculated.

3 1050050 - ×× = m

mw (A.3)

Where.

Quality m3- sample value in units of grams (g);

Numerical test compound iron quality m4- by the work of Richard curve or linear regression equation calculated in milligrams (mg).

Take the parallel determination results as the arithmetic mean of the results of the report, the results of two parallel determination of the absolute difference is not more than 10 mg/kg.

A.7 Determination of Heavy Metals A.7.1 Method summary Under weakly acidic (pH3 ~ 4) conditions, heavy metal ions and sulfide ions generated brown-black precipitate of lead standard solution with the same treatment of Compare, for a limited test.

A.7.2 Reagents and materials A.7.2.1 hydrochloric acid.

A.7.2.2 hydrogen peroxide solution. 1 + 5.

A.7.2.3 acetic acid - sodium acetate buffer solution. pH~3.

A.7.2.4 saturated solution of hydrogen sulfide.

The hydrogen sulphide-free carbon dioxide gas into water, up to saturation. This solution is using now.

A.7.2.5 Lead standard solution. 1mL solution containing lead (Pb) 0.1mg.

A.7.2.6 Lead standard solution. 1mL solution containing lead (Pb) 0.01mg.

Pipette 10.00mL lead standard solution (A.7.2.5), placed in 100mL flask, diluted with water to the mark. The solution was active Now equipped.

A.7.2.7 phenolphthalein indicator solution. 10g/L.

A.7.2.8 starch - iodide test paper.

A.7.3 Instruments and Equipment Nessler colorimetric tube. 50mL.

The glassware with 10% to 20% nitric acid soak for more than 24h, repeatedly washed with tap water, and finally rinse with water.

A.7.4 Analysis step

A.7.4.1 A tube. Pipette 1.00mL lead standard solution (A.7.2.6) into 50mL Nessler colorimetric tube, add water to 25mL, add 5mL of acetic acid - Sodium acetate buffer solution, shake. spare.

A.7.4.2 B Tube. A tube and take a supporting Nessler colorimetric tube, pipette 25.00mL A sample solution, placed in 50mL Nessler colorimetric tube, Add water to 25mL, solution of hydrogen peroxide solution, free of hypochlorite to date (not the starch - iodide test paper turns blue). Add 1 drop of phenolphthalein indicator Washed with hydrochloric acid to reddish, plus 5mL of acetic acid - sodium acetate buffer solution, shake. spare.

A.7.4.3 C Tube. take one with A, B tube supporting 50mL Nessler colorimetric tube, add the same sample solution and the same amount of tube B, then add A tube with an equal volume of lead standard solution (A.7.2.6), add water to 25mL, titration solution of hydrogen peroxide, hypochlorite to free up (not to precipitate Powder - iodide test paper turns blue). Add 1 drop of phenolphthalein indicator solution, adjusted with hydrochloric acid to a reddish color, then add 5mL of acetic acid - sodium acetate buffer solution, shake uniform. spare.

A.7.4.4 each tube was added a saturated solution of hydrogen sulfide freshly prepared 10mL, 50mL, add water to volume, and mix in a dark place 5min.

Observation on white background, B can not be deeper than the color tube A tube of color, C color shall A tube tube color tube equal to or deeper than the A chromaticity.

A.8 Determination of Arsenic A.8.1 Method summary in the presence of potassium iodide and stannous chloride, high arsenic reduced to trivalent arsenic, nascent hydrogen trivalent arsenic and zinc particles and acid generator generates arsenide Hydrogen, sulfide is removed interference regenerated by lead acetate cotton and mercuric bromide paper yellow to orange spots, and do relatively limited standard Gutzeit the amount of testing.

A.8.2 Reagents and materials A.8.2.1 hydrochloric acid.

A.8.2.2 hydrogen peroxide solution. 1 + 5.

A.8.2.3 potassium iodide solution. 150g/L;

Weigh 15.0g of potassium iodide, dissolved in water and diluted with water to 100mL.

A.8.2.4 solution of stannous chloride. 400g/L.

A.8.2.5 arsenic standard solution. 1mL solution containing arsenic (As) 0.1mg.

A.8.2.6 arsenic standard solution. 1mL solution of arsenic (As) 1.0µg.

Pipette 1.00mL arsenic standard solution (A.8.2.5), placed in 100mL volumetric flask, dilute to 100mL, shake. The solution is using now.

A.8.2.7 Lead acetate cotton.

A.8.2.8 mercuric bromide paper.

A.8.2.9 starch - iodide test paper.

A.8.2.10 zinc particles.

A.8.3 Instruments and Equipment Arsenic instrument given in Figure A.1.

Millimeters

a-100mL flasks;

b- absorption tube;

c- absorption tube cap.

Figure A.1 given arsenic meter schematic

A.8.4 Analysis step

A.8.4.1 Pipette 1.00mL arsenic standard solution (A.8.2.6) into a given arsenic instrument Erlenmeyer flask, add 5mL hydrochloric acid, add water to 30mL, plus 5mL potassium iodide solution and 5 drops of stannous chloride solution, shake and let stand 10min.

A.8.4.2 Pipette 25.00mL A sample solution of arsenic placed in a given instrument Erlenmeyer flask, a solution of hydrogen peroxide solution, free of hypochlorite to date (not the starch - iodide test paper turns blue). Sample solution was neutralized with hydrochloric acid and to neutrality, and 5mL excess hydrochloric acid, water was added to 30mL, plus 5mL iodide Potassium solution and 5 drops of stannous chloride solution, shake and let stand 10min.

A.8.4.3 to each of the respective conical flask add 2g zinc tablets, has been installed immediately lead acetate cotton and mercuric bromide paper absorption tube connected, to 25 °C, dark place for 1h.

A.8.4.4 Remove Gutzeit, the sample solution can not be deeper than Gutzeit arsenic limits Gutzeit. Each determination should also be prepared using standard Gutzeit.