气相色谱-质谱法测定酱猪蹄和酱猪肘中5种胆固醇氧化物

建立了气相色谱-质谱(GC-MS)测定酱猪蹄和酱猪肘中7β-羟基胆固醇、5α,6α-环氧化胆固醇、胆甾烷-3β,5α,6β-三醇、25-羟基胆固醇和7-酮基胆固醇5种胆固醇氧化物(COPs)含量的方法。样品经甲醇-氯仿(1∶2, v/v)混合溶液提取,硅胶固相萃取小柱净化后,加入N,O-双(三甲基硅基)乙酰胺-三甲基氯硅烷-三甲基硅基咪唑(3∶2∶3, v/v/v)(Sylon BTZ)进行衍生化处理,设置合理的柱温升温程序,采用选择离子扫描(SIM)模式进行检测。在优化条件下,5种COPs在22 min内实现分离,且分离度良好。5种COPs的线性范围满足测定要求,3个加标水平下的平均回收率为61.16%～96.96%,相对标准偏差≤7.80%(n=3),检出限(以信噪比为3计)和定量限(以信噪比为10计)分别为0.02～47.07 ng/g和0.06～156.90 ng/g。该法快速简便,线性范围广,灵敏度高,可作为测定实际样品中COPs的有效方法。

Determination of five cholesterol oxidation products in marinated pig feet and hocks by gas chromatography-mass spectrometry

An analytical method was developed for the simultaneous determination of five cholesterol oxidation products (COPs) in marinated pig feet and hocks by gas chromatography-mass spectrometry (GC-MS). The five COPs were 7 β -hydroxycholesterol, cholesterol-5 α,6 α -epoxide, 3 β,5 α,6 β -trihydroxycholestane, 25-hydroxycholesterol and 7-ketocholesterol. The sample was extracted with methanol-chloroform (1:2, v/v) and purified by solid phase extraction. Subsequently, the sample was collected for derivatization by N,O-bis(trimethylsilyl)acetamide-trimethyl chlorosilane-1-trimethylsilyllimidazole (3:2:3, v/v/v) (Sylon BTZ). The column temperature was properly programmed, and the selected ion monitoring (SIM) mode was used for the determination of COPs. Under optimum conditions, the five COPs were well separated within 22 min with good separation. The linear range of the five COPs met the requirement of determination, and the average recoveries of the five COPs spiked in the pork samples at three levels were 61.16%-96.96% with relative standard deviations (RSDs) no more than 7.80% (n=3). The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.02-47.07 ng/g and 0.06-156.90 ng/g, respectively. This method has a wide line arrange and high sensitivity, and has been successfully applied to the analysis of COPs in actual samples.