GB 25581-2010National food safety standards of food additives potassium ferrocyanide (potassium ferrocyanide) (English PDF)

Foreword

Appendix A of this standard is a normative appendix.

National Food Safety Standard Food additive potassium ferrocyanide (potassium ferrocyanide)

1 Scope

This standard applies to food additive potassium ferrocyanide (potassium ferrocyanide).

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 this applies 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

K4Fe (CN) 6 · 3H2O

4 Technical Requirements

4.1 Sensory requirements. comply with Table 1.

Table 1 Sensory requirements

Project requires test methods Pale yellow color take appropriate sample is placed in a beaker 50mL watch in natural light Observing the color and texture. State organization crystalline particles or powder

4.2 Physical indicators. to comply with Table 2.

Table 2. Physical and chemical indicators

Item Index Test Method Potassium ferrocyanide [K4Fe (CN) 6 · 3H2O], w /% >= 99.0 Appendix A A.4 Chloride (Cl dollars), w /% <= 0.3 A.5 in Appendix A Water-insoluble, w /% <= 0.02 A.6 in Appendix A Sodium (Na), w /% <= 0.2 A.7 Appendix A Arsenic (As)/(mg/kg) <= 1 Appendix A A.8 Cyanide by examining Appendix A, A.9 Hexacyanoferrate (III) salt by test A.10 in Appendix A Appendix A (Informative) Testing method A.1 Warning Reagents and samples of the standard test methods use toxic or corrosive, the operation should be cautious as splashed on skin should immediately wash with water, severe cases should be treated immediately.

A.2 General Provisions the standard test methods used in the reagents and water in the absence of other specified requirements, refer to analytically pure reagents and GB/T 6682-2008 Three water regulations. Impurities used in the test standard solution, preparations and products, did not indicate when the other requirements, according to HG/T 3696.2, HG/T 3696.3 regulations of preparation.

A.3 Identification Test A.3.1 Reagents and materials A.3.1.1 ammonia.

A.3.1.2 perchloric acid solution. 110.

A.3.1.3 sulfuric acid solution. 18.

A.3.1.4 sodium hydroxide solution. 10g/L.

A.3.1.5 ferric chloride solution. 5g/L.

A.3.2 Analysis step

A.3.2.1 Identification of ferrocyanide Take 10mL10g/L of the sample solution, ferric chloride solution was added 1mL generated dark blue precipitate was filtered and the filtrate make the following experiment.

Take the above filtrate was neutralized with ammonia water to neutral, and concentrated to one-third, add 2 drops of perchloric acid solution that is a white precipitate, hydroxide Soda solution or water insoluble, can be dissolved in sulfuric acid solution.

A.3.2.2 Identification of potassium ions Take a platinum wire wetted with hydrochloric acid, the colorless to colorless flame, burning the sample dipped in a colorless flame, fire in cobalt glass Flame was purple.

A.4 Determination of potassium ferrocyanide A.4.1 Method summary in acidic medium, with zinc sulfate standard titration solution titrated with hexacyanoferrate acid tripotassium and diphenylamine as indicator for the end of mixing.

A.4.2 Reagents and materials A.4.2.1 sulfuric acid solution. 18.

A.4.2.2 hexacyanoferrate acid tripotassium solution. 10g/L (using now).

A.4.2.3 ammonia - ammonium chloride buffer solution (A). pH~10.

A.4.2.4 disodium edetate (EDTA) standard titration solution. c (EDTA) = 0.03mol/L.

A.4.2.5 zinc sulfate standard titration solution. c (ZnSO4) = 0.03 mol/L;

Preparation and calibration. weigh 9.0g zinc sulfate heptahydrate dissolved in water 1000mL, shake. Pipette 30.00mL ~ 35.00mL preparation Good zinc sulfate solution and placed in 250mL conical flask, add 70mL water, 10mL ammonia - ammonium chloride buffer solution, add 5 drops of chrome black T directions Washed with disodium edetate (EDTA) titration standard solution titration solution from purple to pure blue. Make a blank test simultaneously.

Blank test. Measure 100mL ~ 105mL of water, placed in 250mL conical flask, add 10mL ammonia - ammonium chloride buffer solution (A), from "Add 5 drops of chrome black T indicator solution" Start with the calibration while the same operation.

Zinc sulfate (ZnSO4) standard titration solution concentration c by the formula (A.1) Calculated.

cVV

c 101

Where.

Numerical standard titration solution volume V1-- titration zinc sulfate solution consumed edetate disodium (EDTA), in units of milli L (mL of);

Numerical standard titration solution volume V0-- titrate blank solution consumed edetate disodium (EDTA), milliliters (ML of);

c1-- disodium edetate (EDTA) Standard Solution accurate value in units of moles per liter (mol/L);

Pipette value V-- zinc sulfate solution volume in milliliters (mL).

A.4.2.6 chrome black T indicator solution. 5g/L.

A.4.2.7 diphenylamine indicator solution. 10g/L.

The 1g diphenylamine was dissolved in 100mL of concentrated sulfuric acid.

A.4.3 Analysis step

Weigh about 5g samples, accurate to 0.000 2g, set 500mL flask, dissolved in water and diluted to the mark. This solution Solution as the test solution A, this solution is used potassium ferrocyanide, chloride, cyanide and hexacyanoferrate (III) salts measurement and testing.

Pipette 25.00mL test solution A, placed in 500mL conical flask, add 20mL sulfuric acid solution, 3 drops to 5 drops of diphenylamine indicator solution, 3 drops to 5 drops hexacyanoferrate acid tripotassium solution, add water to 100mL, under vigorous stirring, zinc sulfate standard titration solution titration solution from yellow to green to blue to purple end.

A.4.4 Calculation Results Potassium ferrocyanide to potassium ferrocyanide [K4Fe (CN) 6 · 3H2O] mass fraction w1 and its value is expressed in%, according to formula (A.2) Calculated.

() 01000500251 ××× = m VcMw (A.2) where.

Numerical zinc sulfate standard titration V-- titration solution consumed volume in milliliters (mL);

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

Numerical m-- sample mass, expressed in grams (g);

Numerical M-- potassium ferrocyanide [2/3K4Fe (CN) 6 · 3H2O] molar mass in grams per mole (g/mol) (M = 281.6).

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 0.3%.

A.5 Determination of chloride A.5.1 Reagents and materials with GB/T Chapters 4 and zinc nitrate solution in 3051-2000. 150g/L.

A.5.2 Instruments and Equipment with GB/T 3051-2000 of Chapter 5.

A.5.3 Analysis step

With 100 mL pipette twice totaling 200.00 mL test solution A (A.4.3), placed in 250 mL volumetric flask, add nitric acid Zinc solution to the mark. Place stratified, with a slow dry filter paper, discard the initial filtrate, Pipette 100mL filtrate was placed in 300mL Erlenmeyer flask, add 3 drops of bromophenol blue indicator solution, nitric acid solution was dropped to just yellow, then 5 drops of excess. Add 1mL diphenylcarbazone hydrazide Indicator solution, the use of micro-burette with 0.05mol/L nitrate mercury standard titration solution titration solution from yellow to purple.

Blank test. 100mL water is placed 300mL conical flask, from "add 3 drops of bromophenol blue indicator solution" Start with the sample at the same time the same operation.

The waste collected after titration, according to the provisions of GB/T 3051-2000 Appendix D treatment.

A.5.4 Calculation Results Chloride content quality chlorine (Cl) scores w2 and its value is expressed in%, according to formula (A.3) Calculated.

() () 01000250100500200 ) (0 2 ×××× - = cMVV w (A.3) where.

Numerical nitrate mercury standard titration solution consumed V-- titration solution volume in milliliters (mL);

V0 - Numerical mercury nitrate standard solution titration solution consumed blank titration volume in milliliters (mL);

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

m - A.4.3 said the value of the quality of the sample taken in units of grams (g);

M-- value chlorine (Cl) molar mass of the units of grams per mole (g/mol) (M = 35.45).

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 0.03%.

A.6 Determination of insoluble matter A.6.1 Reagents and materials Ammonium ferric sulfate solution. 50g/L.

A.6.2 Instruments and Equipment A.6.2.1 sintered glass crucible. filter plate pore size of 5 µm ~ 15 µm.

A.6.2.2 electric oven. the temperature can be controlled at 105 °C ~ 110 °C.

A.6.3 Analysis step

It weighs about 50g sample, accurate to 0.1g, placed in 500mL beaker, add 100mL ~ 150mL water, stirred and heated to Sample End Totally dissolved, was used at 105 °C ~ 110 °C drying to constant quality glass sand crucible filtered hot, washed with hot water until dissolved ammonium ferric sulfate Fluid test, no blue appears. The glass sand crucible together with insolubles be transferred to the electric oven at 105 °C ~ 110 °C Dried to a constant mass.

A.6.4 Calculation Results Water-insoluble mass fraction w3 and its value is expressed in%, according to formula (A.4) Calculated.

0213 × - = m

mmw (A.4)

Where.

m1-- sand glass crucible together with the quality of insolubles values in grams (g);

Numerical m2-- sintered glass crucible mass in grams (g);

m-- sample mass value in grams (g).

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 0.005%.

Determination A.7 Sodium A.7.1 Reagents and materials A.7.1.1 sodium standard solution. 1mL solution of sodium (Na) 0.01mg.

Preparation. Pipette 1.00mL sodium standard solution according to HG/T 3696.2 prepared, placed in 100mL volumetric flask, dilute to the mark with water, shake uniform.

A.7.1.2 two water. in line with GB/T 6682-2008 requirements.

A.7.2 Instruments and Equipment Atomic absorption spectrometer (flame emission having a working mode) or flame spectrophotometer.

A.7.3 Analysis step

Weigh about 0.5g sample, accurate to 0.001g, placed in 100mL volumetric flask, add water to the mark. Pipette 2.00mL respectively the solution was placed in four 100mL flask, then were added 0.00 mL, 2.00 mL, 4.00mL, 8.00mL sodium standard solution, Add water to the mark. By flame atomic absorption spectrometry or flame emission spectrophotometer to work at 589.0nm wavelength, Air - acetylene flame measured the absorbance of each solution.

To the quality of the sodium standard solution of sodium (mg) as abscissa and the corresponding absorbance for the vertical axis, draw the curve, reverse curve extended Intersects with the abscissa, the quality of the solution of sodium intersection is measured.

A.7.4 Calculation Results Sodium content of sodium (Na) mass fraction w4 and its value is expressed in%, according to formula (A.5) Calculated.

() 01002

mw (A.5)

Where.

Quality m1-- value from the working curve Richard sodium in milligrams (mg);

m-- sample mass value in grams (g).

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 0.02%.

A.8 Determination of Arsenic Weigh 2.00 g ± 0.01g sample was placed in a conical flask arsenic measuring device, add approximately 40mL dissolved in water, the following according to GB/T 5009.76-2003 Chapter 11 was measured.

Limits formulated solution. Pipette 2.00mL arsenic standard solution [1mL solution containing 1.0µg arsenic (As)], and the same sample at the same time Sample processing.

A.9 cyanide test

A.9.1 Reagents and materials A.9.1.1 ammonia solution. 14.

A.9.1.2 copper sulfate solution. 1g/L;

0.1g of copper sulfate dissolved in 100mL ammonia.

A.9.2 Analysis step

The copper sulfate solution with a wet filter paper, placed in a stream of hydrogen sulfide, filter paper was brown, 1 drop of solution A test on filter paper (A.4.3) does not produce white qualified.

A.10 hexacyanoferrate (III) acid test A.10.1 reagents and materials A.10.1.1 lead nitrate solution. 10g/L.

A.10.1.2 benzidine saturated acetic acid solution. benzidine was dissolved in (17) to a saturated solution of acetic acid.

A.10.2 Analysis steps the test solution A (A.4.3) was diluted 10-fold, dropping 1 drop test plate, add 1 drop of a solution of lead nitrate, lead acetate plus a few drops of solution, no blue or blue precipitate appears acceptable.