1 Scope
This standard specifies the liquid chromatography method for the determination of trans fatty acids in foods.
This standard is applicable to the determination of trans fatty acids in animal and vegetable oils, hydrogen vegetable oils, refined vegetable oils and frying oils and foods containing animal and vegetable oils, hydrogen vegetable oils, refined vegetable oils and fried oils.
This standard is not applicable to the determination of food sample of free fatty acid content greater than 2%.
2 Theory
The animal or vegetable oil sample or the fats in food sample extracted by the acid hydrolysis method is transesterified with methanol under alkaline conditions to form a fatty acid methyl ester, which is separated on a strongly polar stationary phase capillary column. The fatty acid methyl ester is determined by a gas chromatograph equipped with a hydrogen flame ionization detector and quantified by area normalization method.
3 Reagents and Materials
Unless otherwise specified, reagents used in this method are all analytically pure, and water is the Grade 1 water as specified in GB/T 6682.
3.1 Reagents
3.1.1 Hydrochloric acid (HCl, ρ20=1.19): 36% to 38%.
3.1.2 Ether (C4H10O)
3.1.3 Petroleum ether: boiling range 30°C to 60°C.
3.1.4 Anhydrous ethanol (C2H6O): chromatographically pure.
3.1.5 Anhydrous sodium sulfate: burned at a temperature of 650°C for 4h; store in drying units on standby.
Foreword I
1 Scope
2 Theory
3 Reagents and Materials
4 Apparatuses
5 Analytical Procedures
6 Expression of Analysis Results
7 Precision
8 Others
Annex A Standard Information
Annex B Standard Chromatogram
Annex C Calculation of FID Response Factor and FID Calibration Factor
Annex D FID Response Factor and FID Calibration Factor