Detail of GB 5009.251-2016

Introduction of GB 5009.251-2016

1 Scope This standard specifies the methods for the determination of 1,2-propanediol in foods by gas chromatography and gas chromatography - mass-spectrography. The first method of this standard is applicable to the determination of 1,2-propanediol content in cakes, puffed foods, cream, cheese, bean products, milk tablets, raw and wet flour products, frozen drinks, liquid milk, vegetable protein drinks, milk powder, butter and cream. The second method is suitable for the determination of 1,2-propanediol in pastry, puffed foods, cheese, bean products, milk tablets and raw and wet flour products. Method I Gas chromatography 2 Principle The 1,2-propanediol in the sample shall be extracted with absolute ethanol, and the extract shall be filtered and determined by gas chromatography. The extract shall be qualified as per retention time and quantified by the external standard method. 3 Reagents and materials Unless otherwise specified, analytically-pure reagents and Grade II water specified in GB/T 6682 are adopted for the purpose of this method. 3.1 Reagents 3.1.1 Anhydrous ethanol (C2H5OH). 3.1.2 Sea sand. 3.1.3 Acetonitrile (CH3CN). 3.1.4 n-hexane [CH3(CH2)4CH3]. 3.2 Preparation of reagents 3.2.1 N-hexane saturated acetonitrile solution: Take the same volume of acetonitrile and n-hexane, put them in a separating funnel and oscillate. Left the solution to stratify and take the lower-layer solution. 3.2.2 Acetonitrile saturated n-hexane solution: Take the same volume of acetonitrile and n-hexane, put them in a separating funnel and oscillate. Left the solution to stratify and take the upper-layer solution. 3.3 1,2-propanediol standard (CH2OHCHOHCH3) Purity: ≥ 99.9%. 3.4 Preparation of standard solutions 3.4.1 1,2-propanediol standard stock solution (10.0 mg/mL): Accurately weigh 1 g of 1,2-propanediol standard sample (accurate to 0.0001 g), dissolve it in anhydrous ethanol, transfer the solution to a 100 mL volumetric flask, and dilute the solution with water to the scale. The mass concentration of 1,2-propanediol in this solution is 10.0 mg/mL. Store the solution in a refrigerator at 4°C, with a validity period of three months. 3.4.2 1,2-propanediol standard series working solution: Accurately pipette 1,2-propanediol standard working solution, dilute step by step with anhydrous ethanol to prepare the 1,2-propanediol standard series solution with mass concentrations of 0.00 μg/mL, 2.00 μg/mL, 5.00 μg/mL, 10.0 μg/mL, 20.0 μg/mL and 50.0 μg/mL. Prepare the solution immediately before use. 4 Instruments and apparatus 4.1 Gas chromatograph (GC): equipped with a hydrogen flame ionization detector (FID). 4.2 Analytical balance: with the sensitivity of 0.01 g and 0.0001 g. 4.3 Pulverizer. 4.4 Vortex mixer. 4.5 Orbital shaker. 4.6 Centrifuge: with a rotating speed ≥ 8,000 r/min.

Contents of GB 5009.251-2016

Foreword i 1 Scope 2 Principle 3 Reagents and materials 4 Instruments and apparatus 5 Analytical procedures 6 Expression of analysis results 7 Precision 8 Other requirements 9 Principle 10 Reagents and materials 11 Instruments and apparatus 12 Analytical procedures 13 Expression of analysis results 14 Precision 15 Other requirements Annex A Gas chromatogram of 1,2-propanediol standard sample solution Annex B Selective ion flow diagram and ion mass spectrogram of 1,2-propanediol