GB/T 21703-2008National food safety standard -- Determination of benzoic acid and sorbic acid in milk and milk products (English PDF)

Foreword

This revised standard adopts the International Dairy Federation standard IDF 139. 1987 Milk, dried milk, yogurt and other fermented milks-Determination of benzoic and sorbic acid.

Appendix A of this standard is an informative annex.

This standard replaces the standards previously issued as follows.

--GB/T 21703-2008.

National Food Safety Standard Milk and milk products Determination of benzoic acid and sorbic acid

1 Scope

This standard specifies the method for determination of milk and dairy products benzoic acid and sorbic acid content.

This standard applies to milk and dairy products Determination of benzoic acid and sorbic acid content.

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 Apply to this standard. For undated references, the latest edition (including any amendments) applies to this standard.

Principle 3

Removal of fat and protein in the sample, diluted with methanol, filtered by reverse-phase liquid chromatography separation and determination.

4 Reagents and materials

Unless otherwise specified, the reagents used in this method are analytically pure water GB/T 6682 provided a water use.

4.1 methanol (CH3OH). chromatography.

4.2 potassium ferrocyanide solution (92 g/L). Weigh potassium ferrocyanide [K4Fe (CN) 6 · 3H2O] 106 g, was dissolved in 1000 mL of water capacity Flask, dilute to the mark and mix.

4.3 zinc acetate solution (183 g/L). Weigh zinc acetate [Zn (CH3COO) 2 · 2H2O] 219 g, was added 32 mL of acetic acid was dissolved in water 1000 mL volumetric flask, dilute to the mark and mix.

4.4 phosphate buffer (pH = 6.7). Weigh 2.5 g of potassium dihydrogen phosphate (KH2PO4) and 2.5 g potassium phosphate dibasic (K2HPO4 · 3H2O) in 1000 mL volumetric flask, dilute to the mark with water and mix, filtered through a membrane filter (4.9) alternate.

4.5 sodium hydroxide solution (0.1 mol/L). Weigh 4 g of sodium hydroxide (NaOH), was dissolved in 1000 mL volumetric flask with water, the volume to the mark and mix.

4.6 sulfuric acid solution (0.5 mol/L). Pipette 30 mL of concentrated sulfuric acid (H2SO4) to 500 mL of water was added slowly with stirring, cooled After cooling to room temperature, transferred to a 1000 mL volumetric flask, dilute to the mark and mix.

Aqueous methanol 4.7. volume fraction of 50%.

5 Apparatus

5.1 high performance liquid chromatography with UV detection.

5.2 Balance. a sense of the amount of 0.1 mg, 0.01 g.

6 Step, Analysis

7 Expression analysis

Sample benzoic acid, sorbic acid content in accordance with the formula (1) is calculated.

VcA

Where.

X - a sample of benzoic acid, sorbic acid content in milligrams per kilogram (mg/kg);

A-- sample solution of benzoic acid, sorbic acid peak area;

As - standard solution of benzoic acid, sorbic acid peak area;

cs - the concentration of standard solution, in micrograms per milliliter (µg/mL);

V - the final volume of the sample, in milliliters (mL);

m - sample mass, in grams (g).

The arithmetic mean of two under the same condition of independent determination results indicated that the results to three significant figures.

8 Precision

Two independent determination results under the absolute difference in repeatability condition must not exceed 10% of the arithmetic mean.

9 Other

The benzoic acid, sorbic acid detection limits were 1 mg/kg.

Appendix A

(Informative)

Benzoate, sorbic typical chromatogram Determination A.1 HPLC benzoic acid, sorbic typical chromatogram Determination of benzoic acid, sorbic typical chromatogram shown in Figure A.1.

Figure A.1 benzoic acid, sorbic acid, typical chromatogram