GB 5009.251-2016National food safety standard - Determination of 1,2-propylene glycol in food (English PDF)

3.1 Reagents

3.1.1 Anhydrous ethanol (C2H5OH).

3.2 Preparation of reagent

3.2.1 N-hexane saturated acetonitrile solution. Take the same volume of

acetonitrile and n-hexane. Place in a separatory funnel. Oscillate. Perform static

layering. Take the lower layer solution.

3.2.2 Acetonitrile saturated n-hexane solution. Take the same volume of

acetonitrile and n-hexane. Place in a separatory funnel. Oscillate. Perform static

layering. Take the upper layer solution.

3.4 Preparation of standard solution

3.4.1 1,2-propylene glycol standard stock solution (10.0 mg/mL). Accurately

weigh 1 g of 1,2-propylene glycol standard sample (to the nearest of 0.0001g).

Use absolute ethanol to dissolve and transfer to a 100mL volumetric flask. Set

volume to the scale. The mass concentration of 1,2-propylene glycol of this

solution is 10.0 mg/mL. Store in a refrigerator at 4°C. It shall be valid for 3

months.

4.1 Gas chromatograph (GC). equipped with hydrogen flame ionization detector

(FID).

4.4 Vortex mixer.

4.5 Cyclotron oscillator.

4.6 Centrifuge. rotating speed>=8000 r/min.

5.1 Preparation of specimen

5.1.1 Pastries, puffed food, cheese, soy products, milk tablets

The specimen is crushed by the mincer. Accurately weigh 5 g of well-mixed

specimen (to the nearest of 0.01g) to a 100mL stoppered conical flask. Add into

50.0 mL of absolute ethanol. Vortex and mix for 2min, then perform oscillation

extraction for 40min. After standing for 1h, use 0.45µm organic phase filter

membrane to filter. The filtrate obtained is put into gas chromatograph for

analysis.

5.1.3 Frozen drinks

A solid specimen is placed in a dry beaker to unfreeze. After melting, use a

glass rod to smash and stir evenly. The liquid specimen is put at room

temperature and shaken evenly.

5.1.4 Liquid milk, vegetable protein drinks

Accurately weigh 10 g of well-mixed specimen (to the nearest of 0.01g) into a

50mL stoppered colorimetric tube. Use absolute ethanol to set volume. Vortex

and mix for 2min. After standing for 1h (centrifuge at 8000 r/min for 5min if

necessary), use 0.45µm organic phase filter membrane to filter. The filtrate

obtained is put into gas chromatograph for analysis.

5.1.5 Milk powder

Accurately weigh 2 g of well-mixed specimen (to the nearest of 0.01g) into a

50mL stoppered colorimetric tube. Use 8 mL of 40°C water to dissolve and well

mix. Use absolute ethanol to set volume. Vortex and mix for 2min. After standing

for 1h (centrifuge at 8000 r/min for 5min if necessary), use 0.45µm organic

phase filter membrane to filter. The filtrate obtained is put into gas

chromatograph for analysis.

5.1.6 Butter, cream

Accurately weigh 2 g of well-mixed specimen (to the nearest of 0.01g) into a

50mL stoppered colorimetric tube. Use 6 mL of hexane to dissolve and well mix.

Add into 20 mL of n-hexane saturated acetonitrile solution.

5.2 Instrument reference conditions

5.2.1 Chromatographic column. bonded/crosslinked polyethylene glycol

stationary phase quartz capillary column, 60m × 0.25mm, 0.25µm, or equivalent

column.

5.2.2 Carrier gas. high purity nitrogen; constant current mode, column flow rate

of 1.0 mL/min.

5.2.3 Use program temperature rise. Column initial temperature is 80°C.

Maintain 1min. Rise temperature to 160°C at 20°C/min. Maintain 2min. Then

rise temperature to 220°C at 15°C/min. Maintain 10min.

5.2.9 Injection method. split injection, split ratio of 10.1.

5.3 Production of standard curve

Inject the standard series working solutions into the gas chromatograph.

Determine the peak area of corresponding 1,2-propylene glycol. The standard

curve is drawn by taking the mass concentration of the standard working

solution as the abscissa and the peak area of the chromatographic peak as the

ordinate.

10.1 Reagents

10.1.1 Anhydrous ethanol (C2H5OH).

10.1.2 Sea sand.

10.1.3 Anhydrous sodium sulfate (Na2SO4). burning 4h at 650°C; store in a

sealed dryer, for use.

10.2 1,2-propylene glycol standard product (CH2OHCHOHCH3)

Purity>=99.9%.

10.3 Preparation of standard solution

11.1 Gas chromatography-mass spectrometry (GC-MS). EI source.

11.2 Analytical balances. resolutions of 0.01g and 0.0001g.

11.3 Mincer.

11.5 Cyclotron oscillator.

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