建立了天然奶油和人造奶油中37种脂肪酸的全二维气相色谱-质谱检测方法.样品经甲苯提取、乙酰氯-甲醇(1:9,v/v)溶液甲酯化衍生后,以 DB-5柱(30 m×0.25 mm×0.25 μm)为一维柱、BPX-50柱(2.5 m×0.1 mm× 0.25 μm)为二维柱进行分离.升温程序为50 ℃保持2 min,以20 ℃/min升温至180 ℃,以2.5 ℃/min升温至250 ℃,以3 ℃/min升温至300 ℃,保持5 min.在调制周期为5 s、扫描范围为 m/z 40~385的条件下,奶油中37种脂肪酸得到了有效分离和准确测定.将该方法应用于实际样品的分析,检测结果比传统的气相色谱法更灵敏,脂肪酸组成也更丰富,可有效鉴别不同种类奶油的差异成分.该方法不仅为奶油中脂肪酸成分分析提供了新的技术手段,同时在保障奶油的质量安全、鉴别掺假伪劣等过程中发挥重要作用.%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 5 s 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 detec-ted. Conclusively,this work suggests a new technical approach in analyzing fatty acids in natu-ral cream and artificial cream,which is meaningful to ensure the quality identification and safety of natural cream.
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