GB 5413.36-2010National food safety standard - Determination of Trans Fatty Acids in Foods for Infants and Young Children (English PDF)

4.1 Petroleum ether. boiling range 30°C ~ 60°C.

4.2 Diethyl ether (C4H10O).

4.3 Ethyl alcohol (C2H6O). volume fraction 95%.

4.4 Normal hexane (C6H14). chromatographically pure.

4.5 Ammonium hydroxide (NH3·H2O). 25% ~ 28%.

4.6 Potassium hydroxide (KOH).

4.7 Methyl alcohol (CH4O).

4.8 Amylase. unit of activity. 1.5 U/mg, adjust its use level in accordance with the

active unit size.

4.9 Anhydrous sodium sulphate (Na2SO4).

4.10 Potassium hydroxide-methyl alcohol solution (4 mol/L). weigh 26.4 g of

potassium hydroxide to dissolve in about 80 mL of methyl alcohol. Cool to room

temperature; use methyl alcohol to add dropwise to 100 mL; add about 5 g of

anhydrous sodium sulphate (4.9); fully stir before filtering; keep the filtrate.

4.11 Fatty acid methyl ester standard substance. methyloctadecanoate (C18.0),

methyl trans-9-octadecenoate (C18.1-9t), methyl cis-9-octadecenoate (C18.1-9c),

methyl trans-9.12-octadecedienoate (C18.2-9t, 12t), methyl cis-9.12-

octadecedienoate (C18.2-9c, 12c). Place in a refrigerator for storage at - 15°C.

4.12 Trans fatty acid methyl ester standard stock solution. the concentrations are

respectively 10.0 mg/mL. Weigh 500 mg (accurate to 0.1 mg) of methyl trans-9-

octadecenoate standard substance and methyl trans-9.12-octadecedienoate standard

substance; use normal hexane to dissolve and add dropwise to 50.0 mL, respectively.

Place in a refrigerator for storage at - 15°C.

4.13 Trans fatty acid methyl ester standard intermediate solution. the concentrations

are 1.0 mg/mL respectively. Absorb 10.0 mL of the two trans fatty acid methyl ester

standard stock solutions (4.12) respectively; add them to the same 100-mL volumetric

flask and use normal hexane (4.4) to add dropwise to scale. Prepare immediately prior

to use. It also works as the maximum concentration of the standard curve.

4.14 Trans fatty acid methyl ester standard working solution. prepare immediately

prior to use. Absorb respectively 0, 2.0, 4.0, 8.0, 10.0 mL of trans fatty acid methyl

ester standard intermediate solution (4.13) to pour into a 10-mL volumetric flask; use

normal hexane to add dropwise to scale. Then obtain the standard working solutions

of concentrations 0, 0.2, 0.4, 0.6, 0.8 and 1.0 mg/mL.

4.15 Fatty acid methyl ester standard mixed solution. use normal hexane to make

fatty acid methyl ester standard substance (4.11) into fatty acid methyl ester standard

mixed solution, with the concentrations of each constituent about 0.05 mg/mL ~ 0.5

mg/mL. Use it for the separation degree and qualitative identification of trans fatty acid

methyl ester.

4.16 Congo red solution. weigh 1 g of Congo red to dilute to 100 mL.

5.1 Gas chromatograph, equipped with hydrogen flame ionization detector.

octadecenoic acid methyl esters or trans octadecadienoic acid methyl esters.

6.2.4 Testing of specimen solutions

Inject the specimen test solutions into the gas chromatograph. See Figure A.1 of Annex

A for the positions of the peaks of trans fatty acid esters in the specimen test solutions.

Measure the peak areas of Area C18.1t and Area C18.2t respectively and search the

standard curves to obtain the mass concentrations of trans octadecenoic acid methyl

esters or trans octadecadienoic acid methyl esters.