Determination of fatty acids in natural cream and artificial cream by comprehensive two-dimensional gas chromatography-mass spectrometry

Abstract

A method for the determination of 37 fatty acids in natural cream and artificial cream was developed by comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS). The samples were extracted with toluene and acetyl chloride-methanol (1:9,v/v) solution was added to the extract for fat esterification. Finally, the fatty acids were analyzed by GC×GC-MS. The GC conditions were as follows:a DB-5 column (30 m×0.25 mm×0.25 μm) was set as the 1st dimensional column and a BPX-50 column (2.5 m×0.1 mm×0.25 μm) was the 2nd dimensional column. The primary oven temperature was programmed from 50℃ (held for 2 min) to 180℃ at a rate of 20℃/min, followed by an increase to 250℃ at 2.5℃/min, then raised up to 300℃ (held for 5 min) at 3℃/min. The ion source temperature was 200℃ with auxiliary temperature of 300℃ in scan mode. All fatty acids were separated effectively and determined accurately while the modulation period was 5s and the scan range of MS was m/z 40-385. This procedure was applied to analyze the fatty acids in commercial natural cream and artificial cream from Chinese markets, among which we found the characteristic components in different kinds of samples. Compared with gas chromatography-flame ionization detector (GC-FID), GC×GC-MS method was more sensitive and more components of fatty acids were detected. Conclusively, this work suggests a new technical approach in analyzing fatty acids in natural cream and artificial cream, which is meaningful to ensure the quality identification and safety of natural cream.