银离子固相萃取-气相色谱法检测食品中的反式脂肪酸

Detection of Trans Fatty Acids in Food with Silver Ion Solid Phase Extraction-Gas Chromatography

[目的]评价银离子固相萃取结合气相色谱（silver ion solid phase extraction-gas chromatography,Ag＋-SPE/GC）对市售加工食品中反式脂肪酸（trans fatty acids,TFA）的定性和定量检测效果。[方法]采用Ag＋-SPE小柱预分离牛肉火腿、豆奶粉和巧克力威化中的TFA甲酯,然后按食品中反式脂肪酸的检测标准（GB/T 22110—2008）进行气相色谱检测。[结果]该方法对食品中TFA甲酯异构体的回收率为71.0%~90.5%,相对标准偏差（relative standard deviation,RSD）均小于13%,该方法对TFA甲酯单标的回收率为84.1%~98.7%,RSD均小于5.6%;最低检出限为10mg/100g（按脂肪计）。牛肉火腿、豆奶粉和巧克力威化中TFA含量依次为37.26mg/100g、24.64mg/100g和162.85mg/100g;3种食品中t C18∶1含量较高,t C18∶2次之,t C18∶3较少;均未检测到t C16∶1。[结论]Ag＋-SPE/GC方法灵敏度较高、分离效果好、重现性好,可以避免顺式脂肪酸和饱和脂肪酸的干扰,适用于乳、肉、巧克力及其制品等食物中TFA含量的测定。

[Objective] To evaluate the quantitative and qualitative detection of trans fatty acids（TFA） in processed foods with silver ion solid phase extraction-gas chromatography（Ag＋-SPE/GC）.[Methods] The fatty acid methyl esters derived from beef ham,soybean flour and chocolate wafer were priorily separated by silver ion solid phase extraction column,and then tested with gas chromatography according to Determination of trans fatty acids in foods-Gas chromatography（GB/T 22110-2008）.[Results] The recoveries of TFA methyl ester isomer in food ranged from 71.0% to 90.5% with the relative standard deviation（RSD） less than 13%.The average recoveries of TFA methyl ester standard ranged from 84.1% to 98.7% with the RSD less than 5.6%.The lowest detection limit was 10 mg/100 g fat.TFA content in beef ham,soybean flour and chocolate wafer were 37.26 mg/100 g,24.64 mg/100 g and 162.85 mg/100 g,respectively.These three types of food were high in t C18∶1,second in t C18∶2,low in t C18∶3,and no for t C16∶1.[Conclusion] The Ag＋-SPE/GC method,with high sensitivity and good separation and repeatability,capable to avoid the interference of cis-and saturated fatty acids,is suitable to detect TFA content in milk,meat,chocolate and their products.