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GB 5009.277-2016 English PDF (GB5009.277-2016)

GB 5009.277-2016 English PDF (GB5009.277-2016)

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GB 5009.277-2016: Determination of sodium hydrogen diacetate in foods -- High performance liquid chromatography method

This Standard specifies the liquid chromatography for the determination of sodium hydrogen diacetate in foods. This Standard applies to the determination of sodium hydrogen diacetate in dried tofu, dried tofu products, unprocessed grains, tapioca pearls, pastries, premade meat products, cooked meat products, cooked aquatic products (edible directly), solid compound seasonings and puffed foods. This Standard does not apply to the determination of seasonings, liquid compound seasonings and food added with acetic acid.
GB 5009.277-2016
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
National food safety standard -
Determination of sodium hydrogen diacetate in foods
ISSUED ON. DECEMBER 23, 2016
IMPLEMENTED ON. JUNE 23, 2017
Issued by. National Health and Family Planning Commission of the
PEOPLE Republic of China;
China Food and Drug Administration.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents and materials ... 4
4 Apparatus ... 5
5 Analytical procedures ... 6
6 Expression of analytical results ... 7
7 Precision ... 8
8 Others ... 8
Annex A Liquid chromatogram of sodium hydrogen diacetate standard
solution ... 9
Annex B Method for the determination of acetic acid background in foods . 10 Foreword
This Standard replaces GB/T 23383-2009, Determination of sodium hydrogen diacetate in foods ?€? High performance liquid chromatography method.
Compared with GB/T 23383-2009, the major technical changes of this Standard are as follows.
-- it changes the name of the standard into ?€?National food safety standard ?€? Determination of sodium hydrogen diacetate in foods?€?;
-- it changes the applicable scope of the standard.
National food safety standard -
Determination of sodium hydrogen diacetate in foods
1 Scope
This Standard specifies the liquid chromatography for the determination of sodium hydrogen diacetate in foods.
This Standard applies to the determination of sodium hydrogen diacetate in dried tofu, dried tofu products, unprocessed grains, tapioca pearls, pastries, premade meat products, cooked meat products, cooked aquatic products (edible directly), solid compound seasonings and puffed foods. This Standard does not apply to the determination of seasonings, liquid compound seasonings and food added with acetic acid.
2 Principle
Sodium hydrogen diacetate in sample is acidized transforming into acetic acid; it is extracted on an ultrasonic water bath or distilled by steam; then it is collected before adjustment of pH, determined through high performance liquid chromatography and quantitated using the external method.
3 Reagents and materials
Unless specified otherwise, all reagents used in this Method are analytically pure; the water used for chromatography is grade one water as specified in GB/T 6682 and the water used for others is grade three water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Phosphoric acid (H3PO4).
3.1.2 Diammonium hydrogen phosphate [(NH4)2HPO4].
3.1.3 Silicone oil [(C2H6OSi)n].
3.2 Preparation of reagents
3.2.1 Phosphoric acid solution (1 mol/L). add 53.5 mL of phosphoric acid into 500 mL of water; after mixing up, add water to make up to 1,000 mL.
3.2.2 Diammonium hydrogen phosphate (1.5 g/L). weigh 1.5 g of diammonium hydrogen phosphate; add water to dissolve and make up to 1,000 mL.
3.3 Standard substance
Sodium hydrogen diacetate standard substance [(CH3COO)2HNa, CAS no.. 126-96-5]. purity ??? 99%.
3.4 Preparation of standard solutions
3.4.1 Standard stock solution (10 mg/mL). Accurately weigh 1 g (accurate to 0.000 1 g) of sodium hydrogen diacetate standard substance; use water to make up to 100 mL. The standard stock solution is stored in a refrigerator at 0??C ~ 4??C; the storage life is 3 months.
3.4.2 Standard working solution. accurately absorb 5.0 mL of standard stock solution to pour into a volumetric flask of 50 mL; use water to dilute to scale; prepare a standard working solution of concentration 1.0 mg/mL. The standard working solution is stored in a refrigerator at 0??C ~ 4??C; the storage life is 1 month.
4 Apparatus
4.1 High performance liquid chromatograph (HPLC). equipped with an ultraviolet detector or a diode array detector.
4.2 Analytical balance. sensitivities 0.000 1 g and 0.01 g.
4.3 Blender.
4.4 Steam distillation apparatus. 500 mL.
4.5 Centrifugal machine. rotational speed ??? 4,000 r/min.
4.6 Stoppered plastic centrifugal tubes. 50 mL.
4.7 Ultrasonic cleaner.
4.8 pH meter.
4.9 Aqueous phase micropore filter membranes of 0.45 ??m.
4.10 Precise pH test paper. pH 0.5 ~ 5.0.
5 Analytical procedures
5.1 Sample preparation
In case of solid sample, take 500 g before using a blender to mix up for use; or in case of liquid sample, shake up for use.
5.2 Sample treatment
5.2.1 The distillation method
Accurately weigh 25 g (accurate to 0.01 g) of sample; place in a distillation flask of 500 mL; add 100 mL of water; use 50 mL of water to rinse the container; transfer to the distillation flask; add 20 mL of phosphoric acid solution (1 mol/L); 2 drops ~ 3 drops of silicone oil; carry out steam distillation; place a volumetric flask of 250 mL in the water bath as the absorption liquid receiver; take out when about 240 mL is distilled; place aside for 30 min at room temperature; use phosphoric acid solution of 1 mol/L to adjust the pH to be about 3; add water to make up; shake up; after filtering through aqueous phase micropore filter membranes of 0.45 ??m, carry out liquid chromatographic determination.
5.2.2 The direct extraction method (apply only to steamed buns and steamed twisted rolls)
Accurately weigh 5 g (accurate to 0.01 g) of sample to place into a beaker of 100 mL; add 20 mL of water; add 0.5 mL of phosphoric acid solution of 1 mol/L; mix up; after ultrasonic extraction for 10 min, use phosphoric acid solution (1 mol/L) to adjust the pH to about 3; transfer sample to a volumetric flask of 50 mL; use water to make up to scale; shake up. Transfer all sample into a stoppered plastic centrifugal tube of 50 mL; carry out centrifugation for 10 min at not lower than 4,000 r/min; take liquid supernatant; after filtering through aqueous phase micropore filter membranes of 0.45 ??m, carry out liquid chromatographic determination.
5.3 Apparatus reference conditions
a) chromatographic column. C18 column, column length 250 mm, internal diameter 4.6 mm and grain diameter 5 ??m, or equivalent;
b) column temperature. 25??C;
c) moving phase. use phosphoric acid solution (1 mol/L) to adjust the pH of diammonium hydrogen phosphate solution (1.5 g/L) to 2.7 ~ 3.5 (prepare
immediately prior to use) and filter using aqueous phase micropore filter membranes of 0.45 ??m;
d) flow rate. 1.0 mL/min;
e) wavelength. 214 nm;
f) volume of sample. 20 ??L;
g) reference conditions for the cleaning of chromatographic column. after test is completed, use methanol 10% to clean for 1 h; then use methanol 100% to clean for 1 h.
5.4 Plotting of standard curve
5.4.1 The distillation method
Accurately absorb 1.0 mL, 2.5 mL, 5.0 mL, 7.5 mL, 10.0 mL and 12.5 mL of sodium hydrogen diacetate standard stock solution to pour into distillation flasks of 500 mL; other operations are as in 5.2.1. The final concentrations of sodium hydrogen diacetate standard solution are respectively 0.04 mg/mL, 0.1 mg/mL, 0.2 mg/mL, 0.3 mg/mL, 0.4 mg/mL and 0.5 mg/mL. Inject them into the liquid chromatograph after filtering through aqueous phase micropore filter membranes of 0.45 ??m; measure the corresponding peak areas; plot the standard curve using the concentrations of standard working solutions as the abscissa and the peak areas as the ordinate.
5.4.2 The direct extraction method
Accurately absorb 0.5 mL, 1.0 mL, 2.0 mL, 3.0 mL, 4.0 mL and 5.0 mL of standard working solution to pour into volumetric flasks of 10 mL; add 0.2 mL of phosphoric acid solution (1 mol/L) respectively; use water to make up to 10 mL. The concentrations of sodium hydrogen diacetate are respectively 0.05 mg/mL, 0.1 mg/mL, 0.2 mg/mL, 0.3 mg/mL, 0.4 mg/mL and 0.5 mg/mL. Inject them into the liquid chromatograph after filtering through aqueous phase micropore filter membranes of 0.45 ??m; measure the corresponding peak areas; plot the standard curve using the concentrations of standard working solutions as the abscissa and the peak areas as the ordinate. 5.5 Determination of sample solution
Inject sample solution into the liquid chromatograph to obtain the peak area; then obtain the concentration of sodium hydrogen diacetate in solution to be tested from the standard curve. For the liquid chromatogram of sodium hydrogen diacetate standard solution see Figure A.1.
6 Expression of analytical results
The content of sodium hydrogen diacetate in sample is calculated in accordance with Equation (1).
where.
X ?€? the content of sodium hydrogen diacetate in sample, in g/kg;
?? ?€? the concentration of sodium hydrogen diacetate in sample solution which is obtained from the standard curve, in mg/mL;
V ?€? the final volume of sample solution made up to, in mL;
1,000 ?€? the conversion coefficient;
m ?€? the mass of sample, in g;
f ?€? the dilution ratio.
The result of calculation is rounded off to three significant digits.
NOTE. If sodium hydrogen diacetate is detected in foods to which sodium hydrogen diacetate is not added as specified in GB 2760 or that the detected value in foods exceeds the limitations to which sodium hydrogen diacetate is added as specified in GB 2760, then the background value of acetic acid in the food sample needs to be determined; the specific operations shall be as specified in Annex B. When the content of sodium hydrogen diacetate in foods is calculated, the content of acetic acid background shall be deducted.
7 Precision
The absolute difference between two results measured independently under repeatable conditions shall not be greater than 10% of their arithmetic mean value. 8 Others
8.1 Limit of detection of the distillation method
When the weight of sample is 25.0 g and the final volume is 250 mL. the limit of detection of the method is 0.030 g/kg; the limit of quantitation of the method is 0.100 g/kg.
8.2 The direct extraction method
When the weight of sample is 5.0 g and the final volume is 50 mL. the limit of detection of the method is 0.015 g/kg; the limit of quantitation of the method is 0.05 g/kg. Annex A
Liquid chromatogram of sodium hydrogen diacetate standard solution
For the liquid chromatogram of sodium hydrogen diacetate standard solution see Figure A.1.
Figure A.1 ?€? Liquid chromatogram of sodium hydrogen diacetate standard
solution
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eti
c a
cid
Annex B
Method for the determination of acetic acid background in foods
B.1 Analytical procedures
B.1.1 Sample preparation
See 5.1.
B.1.2 Sample treatment (the distillation method)
Accurately weigh 25 g (accurate to 0.01 g) of sample; place in a distillation flask of 500 mL; add 100 mL of water; use 50 mL of water to rinse the container; transfer to the distillation flask; 2 drops ~ 3 drops of silicone oil; carry out steam distillation; place a volumetric flask of 250 mL in the water bath as the absorption liquid receiver; take out when about 240 mL is distilled; place aside for 30 min at room temperature; use phosphoric acid solution of 1 mol/L to adjust the pH to be about 3; add water to make up; shake up; after filtering through aqueous phase micropore filter membranes of 0.45 ??m, carry out liquid chromatographic determination.
B.1.3 Apparatus reference conditions
See 5.3.
B.1.4 Plotting of standard curve
See 5.4.1.
B.1.5 Determination of sample solution
See 5.5.
B.2 Expression of analytical results
The content of acetic acid background in sample is calculated in accordance with Equation (2).
where.
X1 ?€? the content of acetic acid background in sample, in g/kg;
??1 ?€? the concentration of acetic acid in sample solution which is obtained from the standard curve, in mg/mL;
V1 ?€? the final volume of sample solution made up to, in mL;
1,000 ?€? the conversion coefficient;
m1 ?€? the mass of sample, in g;
f1 ?€? the dilution ratio.
B.3 Precision
See Clause 7.

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