GB 1886.15-2015National food safety standard - Food additives - Phosphoric Acid (English PDF)

2.1 Molecular formula

H3PO4

2.2 Relative molecular mass

97.99 (according to international relative atomic mass in 2007)

3.1 Sensory requirements

The sensory requirements shall meet the requirements of Table 1.

Table 1 -- Sensory Requirements

Item Requirements Test Methods

Color Colorless, transparent, or with slight light color

Take an appropriate amount of sample and

place it in a clean, dry colorimetric tube, and

visually observe its color and state under

natural light State Viscous liquid

Appendix A

Test Methods

A.1 Safety tips

Some reagents used in this test method are toxic, corrosive and flammable. Operators

should be careful. Rinse immediately with water if splashed on the skin, and treat

immediately, if injured severely. When using flammable materials, it is strictly prohibited

to use open flames for heating.

A.2 General provisions

The reagents and water used in this Standard refer to analytical reagents and Grade-

III water specified in GB/T 6682 when no other requirements are specified. The

standard solutions used in the test, the standard solutions for the determination of

impurities, preparations and products shall be prepared in accordance with GB/T 601

and GB/T 602, and GB/T 603 when no other requirements are specified. When the

solution used in the test is not specified with which solvent, it refers to an aqueous

solution.

A.3 Identification test

A.3.1 Reagents and materials

A.3.2 Identification method

Take about 1g of the sample; put it in a 100mL beaker; add 10mL of water, a drop of

phenolphthalein indicator solution; adjust to neutral by sodium hydroxide solution; add

silver nitrate solution drop-by-drop; form the yellow precipitate; and the precipitate can

be dissolved in diluted nitric acid (5%) or ammonia.

A.4 Determination of phosphoric acid (H3PO4) content

A.4.1 Weight method (Arbitration method)

A.4.1.1 Method summary

In the hydrochloric acid medium, the specimen and the added quimociac precipitant

produce quinoline phosphomolybdate to precipitate. After filtering, washing, drying and

weighing, the phosphoric acid content was determined.

A.4.1.2 Reagents and materials

A.4.1.2.1 Hydrochloric acid.

A.4.1.2.2 Preparation of quimociac solution

A.4.1.3 instruments and equipment

A.4.1.3.1 Glass sand crucible. filter plate pore size 5µm~15µm.

A.4.1.3.2 Electric oven. the temperature can be controlled at 180°C±5°C or

250°C±10°C.

A.4.1.4 Analysis procedures

A.4.1.4.3 Determination

Pipette 10mL of test solution and blank test solution into 250mL beakers respectively;

add water to a total volume of about 100mL; add 50mL of quimociac solution; cover

the watch glass; and heat in the water bath until the contents of the beaker reach

75°C±5°C, keep it for 30s (in the process of adding reagents and heating, open flames

shall not be used, and stirring shall not be performed to avoid condensation and

agglomeration). Take it out and cool to room temperature. Stir for 3~4 times during

cooling. Filter in a glass sand crucible with a constant weight made at 180°C±5°C or

250°C±10°C.

A.4.1.5 Calculation of results

The mass fraction, w1, of phosphoric acid (H3PO4) content is calculated according to

Formula (A.1).

A.4.2 Capacity method

A.4.2.1 Method summary

According to the nature of phosphoric acid, take the thymol phthalein as the indicator

liquid; directly titrate by and the sodium hydroxide standard titration solution to

determine the phosphoric acid content.

A.4.2.2 Reagents and materials

A.4.2.2.1 Sodium hydroxide standard titration solution. c(NaOH) = 1 mol/L.

A.4.2.2.2 Thymol phthalein indicator liquid. 1 g/L.

A.4.2.3 Analysis procedures

A.5 Determination of fluoride (by F)

A.5.1 Method summary

Under neutral conditions, take a saturated calomel electrode as a reference electrode;

and use a fluoride ion selective electrode to directly measure the electrode potential of

the solution. The standard curve method was used to determine the fluorine content.

A.5.2 Reagents and materials

A.5.2.1 Hydrochloric acid solution. 1+1.

A.5.2.5 Bromocresol green indicator liquid. 1 g/L.

A.5.2.6 Fluoride standard solution. 1mL of such solution contains 2µg of fluorine (F).

Prepare just before use. Pipette 2mL of the fluoride standard solution prepared

according to GB/T 602; place it in a 100mL volumetric flask; dilute with water to the

mark; and shake well.

A.5.3 Instruments and equipment

A.5.3.1 Fluoride ion selective electrode.

A.5.4 Analysis procedures

A.5.4.1 Drawing of working curve

Pipette 0.00mL, 1.00mL, 3.00mL, 5.00mL, 7.00mL, 10.00mL of fluoride standard

solutions into the 50mL volumetric flasks, respectively; add 1mL hydrochloric acid

solution, 5 drops of citric acid - trisodium citrate buffer solution and 2 drops of

bromocresol green indicator liquid; adjust the solution to blue by sodium hydroxide

solution;

A.5.4.2 Preparation of test solution

Take about 10g of specimen, accurate to 0.01g; put in a 100mL beaker; dilute with a

small amount of water; adjust to neutral by sodium hydroxide solution; transfer to a

100mL volumetric flask, dilute to the mark by water; and shake well.

A.5.4.3 Determination

Pipette 10 mL of the test solution into a 50 mL volumetric flask; add 1 mL of hydrochloric

acid solution, 5 drops of citric acid - trisodium citrate buffer solution, and 2 drops of

bromocresol green indicator solution; use sodium hydroxide solution to make the

solution blue, and then use nitric acid solution to make the solution just yellow. Add

20mL of citric acid - trisodium citrate buffer solution; dilute with water to the mark; and

mix well. Pour the solution into a 50mL dry beaker; place it on an electromagnetic

stirrer; insert a fluoride ion selective electrode and a saturated calomel electrode;

connect the potentiometer; stir for a while; adjust the potentiometer to zero point; then

measure, and record the potential at equilibrium value. Find the logarithm of the value

of the corresponding fluoride (by F) mass from the standard curve; and check the

inverse logarithm to get the value of the fluoride (by F) mass.

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