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GB 5009.87-2016 English PDF (GB5009.87-2016)

GB 5009.87-2016 English PDF (GB5009.87-2016)

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GB 5009.87-2016: Food safety national standard -- Determination of phosphorus in food

This Standard specifies spectrophotometry and inductively coupled plasma emission spectrum for the determination of phosphorus in foods. Methods 1 and 3 of this Standard are applicable to the determination of phosphorus in various foods. Method 2 is applicable to the determination of phosphorus in foods for infants and young children, milk and milk products.
GB 5009.87-2016
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
National Food Safety Standard -
Determination of Phosphorus in Foods
ISSUED ON. DECEMBER 23, 2016
IMPLEMENTED ON. JUNE 23, 2017
Issued by. National Health and Family Planning Commission of the PRC;
China Food and Drug Administration.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principles ... 4
3 Reagents and materials ... 4
4 Instruments and equipment ... 6
5 Analytical procedures ... 6
6 Analysis results expression ... 8
7 Precision... 9
8 Others ... 9
9 Principles ... 9
10 Reagents and materials... 10
11 Instruments and equipment ... 11
12 Analytical procedures ... 11
13 Analysis results expression ... 12
14 Precision ... 12
15 Others ... 12
National Food Safety Standard -
Determination of Phosphorus in Foods
1 Scope
This Standard specifies spectrophotometry and inductively coupled plasma emission spectrum for the determination of phosphorus in foods.
Methods 1 and 3 of this Standard are applicable to the determination of phosphorus in various foods. Method 2 is applicable to the determination of phosphorus in foods for infants and young children, milk and milk products. Method 1 -- Molybdenum blue spectrophotometry
2 Principles
After the sample is digested, phosphorus, under acidic conditions, is combined with ammonium molybdate to form ammonium phosphomolybdate. This
compound is reduced to blue compound molybdenum blue by hydroquinone,
sodium sulfite, or stannous chloride, hydrazine sulfate. The absorbance value of key blue at 660 nm is directly proportional to the concentration of phosphorus. USE a spectrophotometer to determine the absorbance value of the sample solution; and COMPARE it with standard series to quantify.
3 Reagents and materials
Unless otherwise stated, the reagents used in this method are analytically pure. The water is the Grade III water specified in GB/T 6682.
3.1 Reagents
3.1.1 Sulfuric acid (H2SO4). guaranteed reagent.
3.1.2 Perchloric acid (HClO4). guaranteed reagent.
3.1.3 Nitric acid (HNO3). guaranteed reagent.
3.1.4 Hydrochloric acid (HCl). guaranteed reagent.
3.4.1 Phosphorus standard stock solution (100.0 mg/L). Accurately WEIGH 0.4394 g (accurate to 0.0001 g) of potassium dihydrogen phosphate dried to constant weight at 105 ??C and PLACE it in a beaker; ADD appropriate amount of water to dissolve, and TRANSFER to a 1000 mL volumetric flask; ADD water to dilute to volume and MIX well.
3.4.2 Phosphorus standard use solution (10.0 mg/L). Accurately PIPETTE 10 mL of phosphorus standard stock solution (100.0 mg/L), and PLACE it in a 100 mL volumetric flask; ADD water to dilute to volume and MIX well.
4 Instruments and equipment
4.1 Spectrophotometer.
4.2 Adjustable electric hot plate or adjustable electric heating furnace. 4.3 Muffle furnace.
4.4 Analytical balance. The sensitivity is 0.1 mg and 1 mg.
5 Analytical procedures
5.1 Preparation of samples
During sampling and sample preparation, contamination shall be avoided. 5.1.1 Grain, beans
After removing the dopants, the samples are crushed and stored in plastic bottles.
5.1.2 Vegetables, fruits, fish, meat, and other samples
The samples are washed with water, dried. And the edible part is taken and made into a homogenate, which is stored in a plastic bottle.
5.1.3 Drinks, wine, vinegar, soy sauce, edible vegetable oil, liquid milk, and other liquid samples
SHAKE the samples well.
5.2 Pretreatment for samples
5.2.1 Wet digestion
WEIGH 0.2 g~3 g (accurate to 0.001 g) of the sample or accurately PIPETTE Accurately PIPETTE 2.00 mL of the sample solution and the same amount of blank solution; PLACE them in 25 mL test tubes with stoppers separately; ADD 2 mL of ammonium molybdate solution (50 g/L); SHAKE well and LET stand. ADD 1 mL of sodium sulfite solution (200 g/L) and 1 mL of hydroquinone
solution (5 g/L) and SHAKE well. ADD water to volume and MIX well. After standing for 0.5 h, USE a 1 cm cuvette, at a wavelength of 660 nm, to
DETERMINE the absorbance; and COMPARE it with standard series to quantify. 5.3.2 Stannous chloride, hydrazine sulfate reduction method
5.3.2.1 Making of standard curve
Accurately PIPETTE 0 mL, 0.500 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL, and 5.00 mL of phosphorus standard use solution, equivalent to 0 ??g, 5.00 ??g, 10.0 ??g, 20.0 ??g, 30.0 ??g, 40.0 ??g, and 50.0 ??g of phosphorus content; PLACE them in 25 mL test tubes with stoppers separately; ADD about 15 mL of water, 2.5 mL of sulfuric acid solution (5%), 2 mL of ammonium molybdate solution (50 g/L), and 0.5 mL of stannous chloride-hydrazine sulfate solution; ADD water to 25 mL for each tube and MIX well. After placing at room temperature for 20 min, USE a 1 cm cuvette, at a wavelength of 660 nm, TAKE a zero tube as the
reference, to DETERMINE the absorbance; and based on the absorbance to
phosphorus content, PLOT the standard curve.
5.3.2.2 Determination of sample solution
Accurately PIPETTE 2.00 mL of the sample solution and the same amount of blank solution; PLACE them in 25 mL colorimetric tubes separately; ADD about 15 mL of water, 2.5 mL of sulfuric acid solution (5%), 2 mL of ammonium molybdate solution (50 g/L), and 0.5 mL of stannous chloride-hydrazine sulfate solution; ADD water to 25 mL for each tube and MIX well. After placing at room temperature for 20 min, USE a 1 cm cuvette, at a wavelength of 660 nm, to DETERMINE the absorbance separately; and COMPARE them with standard
series to quantify.
6 Analysis results expression
The phosphorus content in the sample shall be calculated according to the equation (1).
Where.
X - Phosphorus content in the sample, in milligrams per hundred grams or Potassium dihydrogen phosphate (KH2PO4, CAS No.7778-77-0).
Purity>99.99%. Or a phosphorus standard solution of certain concentration which has been certified by the state and awarded a reference material
certificate.
10.4 Preparation of standard solution
Phosphorus standard stock solution (50.00 mg/L). Accurately WEIGH 0.2197 g (accurate to 0.0001 g) of potassium dihydrogen phosphate dried to constant weight at 105 ??C and DISSOLVE it in 400 mL of water; TRANSFER to a 1 L
volumetric flask; ADD water to dilute to volume and MIX well. PLACE in
polyethylene bottle to store it at 4 ??C.
11 Instruments and equipment
Same as those under Chapter 4.
12 Analytical procedures
12.1 Preparation of samples
Same as that under 5.1.
12.2 Pretreatment for samples
Same as that under 5.2.
12.3 Making of standard curve
Accurately PIPETTE 0 mL, 2.50 mL, 5.00 mL, 7.50 mL, 10.0 mL, 15.0 mL of phosphorus standard stock solution in 50 mL volumetric flask; ADD 10 mL of ammonium vanadium molybdate reagent; and USE water to dilute to volume. The mass concentration of phosphorus in this series of standard solutions is 0 mg/L, 2.50 mg/L, 5.00 mg/L, 7.50 mg/L, 10.0 mg/L, and 15.0 mg/L, respectively. Color development at 25 ??C~30 ??C for 15 min. USE a 1 cm cuvette, TAKE a zero tube as the reference, at 440 nm, to DETERMINE the absorbance value. TAKE the absorbance value as the ordinate, the mass concentration of
phosphorus as the abscissa, to make the standard curve.
12.4 Determination of sample solution
Accurately PIPETTE 10 mL of the sample solution and the same amount of
blank solution in a 50 mL volumetric flask; after adding a small amount of water, ADD 2 drops of dinitrophenol indicator (2 g/L); first, USE sodium hydroxide solution (6 mol/L) to adjust to yellow; then, USE nitric acid solution (0.2 mol/L)

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