GB 31631-2014National Food Safety Standard -- Food Additives -- Ammonium chloride (English PDF)

2.2 Relative molecular mass

53.49 (according to 2011 international relative atomic mass)

3.1 Sensory requirements

Shall comply with the requirements in Table 1.

Table 1 Sensory requirements

Project requires test methods Color status white or a crystalline powder Proper amount of sample is placed in a 50mL beaker, under natural light Concept Color and state police

3.2 Physical and Chemical Indicators

Shall be in accordance with Table 2.

Table 2. Physical and chemical indicators

Item Index Test Method Ammonium chloride (NH4Cl) content (dry basis, w) /% >= 99.5 Appendix A A.4 Loss on drying (w) /% <= 0.5 A.5 Residue on ignition (w) /% <= 0.4 A.6 Lead (Pb)/(mg/kg) <= 2 GB 5009.12 Inorganic arsenic (As)/(mg/kg) <= 2 GB 5009.11 or GB 5009.76 Clarity through test A.7 Appendix A Testing method A.1 Warning Reagents used in the present test method is corrosive, the operator should be careful as splashed on the skin immediately wash with water, Yan in severe cases should be treated immediately.

A.2 General Provisions this standard reagents and water, in the absence of other requirements specified, refer to three predetermined water analytical reagents and GB/T 6682 in.

Used in the test standard titration solution, standard solution, the determination of impurities, products and preparations, in the absence of other requirements specified, are by GB/T 601, GB/T 602, GB/T 603 specified prepared. When used in a solution prepared with a solvent which is not specified, refer to an aqueous solution.

A.3 Identification Test A.3.1 Reagents and materials A.3.1.1 nitric acid.

Ammonia solution A.3.1.2. 23.

A.3.1.3 silver nitrate solution. 42g/L.

Sodium hydroxide solution A.3.1.4. 40g/L.

A.3.1.5 red Shi Rui paper.

A.3.2 identification method A.3.2.1 Identification of chloride ions Take a sample of about 0.2g, was added 20mL of water to dissolve, i.e. silver nitrate solution was added to produce a white precipitate, this precipitate insoluble in nitric acid, dissolved in an excess of Ammonia solution.

A.3.2.2 Identification of ammonium Take a sample of about 0.2g, was added 20mL of water was dissolved by adding sodium hydroxide solution, the release of a pungent gas, the humidified gas can Red Shi Rui paper turns blue.

Determination A.4 ammonium chloride (NH4Cl) content (dry basis) of A.4.1 Reagents and materials Sodium hydroxide solution A.4.1.1. 400g/L.

Sulfuric acid solution A.4.1.2. c ( 2H2SO4 ) = 0.5mol/L.

A.4.1.3 sodium hydroxide standard titration solution. c (NaOH) = 0.5mol/L.

A.4.1.4 methyl red - Methylene Blue mixed indicator solution.

A.4.1.5 wide pH test paper.

A.4.1.6 ammonia-free water.

A.4.2 Instruments and Equipment A.4.2.1 distillation apparatus. distillation apparatus according to Figure A.1 equipment, or other device with the same distillation Nitrogen distillation capacity, the instrument port grinding Grease sealed connection should be painted.

In millimeters

Description.

A --- retort;

B --- splash ball bottle;

--- C condenser tube (7 goals);

D --- absorption bottle;

E --- draft tube.

Figure A.1 distillation apparatus of FIG.

A.4.2.2 heating means Distillation. 1000W ~ 1500W electric furnace, placed on lifting the carriage, the height can be adjusted. Electric thermostat can also be used Furnace or other form capable of adjusting the intensity of the heating source.

A.4.2.3 proof Boiling particles. zeolite or glass capillary.

A.4.3 Analysis step

Weigh about 0.9g sample, accurate to 0.0002g, placed in a distillation flask. No ammonia was added 300mL of water, swirling the sample was dissolved. Join Boiling a few grains of explosion particles, connected to the distillation flask to the distillation apparatus. Absorbent flask with 50.0mL pipetted into the sulfuric acid solution was added 4 drops ~ 5 drops of methyl red - Methylene Blue mixed indicator solution, add water, the outlet flow conduit is located about 1.5cm at the absorption liquid surface.

Sodium hydroxide solution was added 20mL distilled off from the bottle, immediately splash plug tube. Opening of cooling water, the heating means is turned on distillation, boiling when adjusting the heating intensity depending on the degree of foam generated, to avoid overflow of foam or droplets out. After distilling off the at least 150mL distillate, widely used Check pH paper effluent droplets, such as the end of the distillation was not alkaline. Rinsed with a small amount of water to the lower end of the draft tube, remove the absorption bottle.

The absorption flask was titrated with standard sodium hydroxide solution was titrated to end point was grayish green.

At the same time a blank test. Blank test (excluding standard titration solution) kind and amount of addition of reagents and other operations except that no sample addition the same assay.

A.4.4 calculation results Ammonium chloride (NH4Cl) content (dry basis) by the mass fraction w1 of formula (A.1) is calculated.

V0-V1 () × c × M

m × (1-w2) × 1000 ×

100% (A.1)

Where.

V0 standard titration volume of sodium hydroxide consumed --- blank test solution, in milliliters (mL);

Standard titration volume Vl --- NaOH solution consumed titration solution in milliliters (mL);

C --- sodium hydroxide concentration standard titration solution in units of moles per liter (mol/L);

--- M ammonium chloride molar mass in grams per mole (g/mol) [M (NH4Cl) = 53.49];

--- m sample mass in grams (G);

--- w2 of mass loss on drying measured A.5 fraction;

1000 --- conversion factor.

The test result to the arithmetic mean of replicates results. Obtained in two independent determination results under repeatability conditions of absolute difference Value is not more than 0.3%.

Determination of loss on drying A.5 A.5.1 Instruments and Equipment A.5.1.1 electric oven. 100 °C ~ 105 °C.

A.5.1.2 weighing bottle. phi50mm × 30mm.

A.5.2 Analysis step

Weigh about 5g sample, accurate to 0.0002g, previously placed in the electric oven 100 °C ~ 105 °C dried to constant mass Given a weighing bottle at 100 °C ~ 105 °C dried to constant mass.

A.5.3 calculation results Loss on drying of the mass fraction w2 by the formula (A.2) is calculated.

m1-m2

m × 100%

Where.

M1 --- weighing bottle and the sample mass before the drying units of grams (G);

--- M2 weighing bottle and the sample after drying mass in grams (G);

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

The test result to the arithmetic mean of replicates results. Obtained in two independent determination results under repeatability conditions of absolute difference is not greater than 0.05%.

Determination of residue on ignition A.6 A.6.1 Instruments and Equipment A.6.1.1 porcelain evaporating dish. a volume of 50mL.

A.6.1.2 temperature furnace. to control the temperature of 500 °C ~ 600 °C.

A.6.2 Analysis step

It weighs about 10g sample to the nearest 0.01g, placed in a constant ignition advance to quality porcelain evaporator on a high temperature oven 500 °C ~ 600 °C in Dish, dye-sublimation placed on a hotplate until no white smoke up, in a high temperature oven 500 °C ~ 600 °C to constant mass in burning.

A.6.3 calculation results Ignition residue content of w3 according to formula (A.3) is calculated.

m1-m2

m × 100%

Where.

After evaporating mass M1 --- porcelain dish and calcined residue, in grams (G);

--- M2 mass porcelain evaporating dish in grams (G);

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

The test result to the arithmetic mean of replicates results. Obtained in two independent determination results under repeatability conditions of absolute difference is not greater than 0.1%.

A.7 Clarity test

A.7.1 Reagents and materials Turbidity standard stock solution A.7.1.1 Weigh 105 °C 1.00g was dried to constant mass of hydrazine sulfate, add water dissolved, if necessary, can be warmed in a water bath at 40 °C Dissolved, transferred to a 100mL volumetric flask, dilute to the mark with water, shake for 4h ~ 6h. Of this solution with an equal volume of hexamethylene Tetraamine solution (100g/L) were mixed shake at 25 °C ± 1 °C dark standing 24h, turbidity standard stock solution was prepared. The solution was placed in a A cool, dark place, use a period of two months, Shake well before using.

A.7.1.2 turbidity standard stock Pipette with a pipette 15.0mL turbidity standard stock solution, set 1000mL volumetric flask, dilute to volume with water and shake. Take appropriate solvent 1cm was placed in a cuvette, using a visible spectrophotometer, zero water, the absorbance was measured at a wavelength of 550 nm of the solution, the absorbance Degree should be between 0.12 to 0.15. The solution should be used within 48h, shake well before using.

A.7.1.3 water

Water used in this test are freshly boiled water and allowed to cool to three GB/T 6682 provisions.

A.7.2 Instruments and Equipment Colorimetric tube. the volume of 100mL, an inner diameter of 15mm ~ 16mm, flat, colorless, should be higher than a height of the glass tube and the color of the color scorelines the same.

A.7.3 Analysis step

Turbidity standard solution A.7.3.1 Preparation of Pipette with a pipette 5.0mL turbidity standard stock solution, put 100mL, diluted with water cuvette to the scale, shake for 5min.

The solution just before use, shake well before using.

A.7.3.2 Determination 10.00g ± 0.01g sample is weighed, placed in a cuvette, add water dissolved, diluted with water to the mark. On a black background, in diffuse light, comparing observed from a horizontal direction, turbidity standard solution was less than the turbidity of sample solution turbidity that is produced by test.

NOTE. Determination should be completed within 5min after the preparation of the sample solution.