ABSTRACT Squalene is the most abundant component in the unsaponifiable fraction of olive oil with strong antioxidant properties. Its concentration in olive oils varies between 0.2 and 16.2 g/kg depending on the cultivar(s) used. The propose of this work was to determine the effectiveness of two different extraction methods for squalene determination by gas chromatography (GC) coupled to a flame ionization detector (FID) or to mass spectrometry (MS). In a first approach, oil samples were dissolved in methanol/acetone mixture 7:3 (v/v) and triglycerides separated by fractional crystallization at −20°C. The organic layer was removed, reduced to dryness and the residue reconstituted in n-heptane (containing squalane as external standard) and analyzed by GC-FID. A headspace (HS) solid phase microextraction (SPME) GC-MS method has been also developed in order to have an environmentally friendly (i.e. solventless) extraction procedure. The linear range investigated with both methods was 1.0-10 g/kg. Within-day and between days precision values, expressed as RSD%, were 4 and 7% (GC-FID), and 3 and 6% (GC-MS), respectively. The limit of detection (LOD) at a signal-to-noise (S/N) ratio of 3 were 0.019 (GC-FID) and 0.003 (GC-MS) g/kg; the limit of quantification (LOQ) calculated at S/N = 10 were 0.063 (GC-FID) and 0.008 (GC-MS) g/kg, well below the typical squalene concentration levels found in olive oils. The obtained percentage recoveries were 70 ± 2 (GC-FID) and 98 ± 3 (GC-MS), and were not concentration dependent. The potential of the method has been demonstrated by the analysis of several different olive oil samples produced from different cultivars and different locations.

中文翻译：

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分步结晶或顶空固相微萃取结合气相色谱法测定橄榄油中的角鲨烯

摘要 角鲨烯是橄榄油不皂化物中含量最丰富的成分，具有很强的抗氧化性能。它在橄榄油中的浓度在 0.2 到 16.2 g/kg 之间变化，具体取决于所使用的栽培品种。这项工作的目的是通过气相色谱 (GC) 与火焰离子化检测器 (FID) 或质谱 (MS) 联用来确定两种不同提取方法对角鲨烯测定的有效性。在第一种方法中，将油样以 7:3 (v/v) 的比例溶解在甲醇/丙酮混合物中，并在 -20°C 下通过分级结晶分离甘油三酯。除去有机层，减干，残留物在正庚烷（含有角鲨烷作为外标）中重新溶解，并通过 GC-FID 进行分析。还开发了顶空 (HS) 固相微萃取 (SPME) GC-MS 方法，以实现环保（即无溶剂）萃取程序。两种方法研究的线性范围为 1.0-10 g/kg。日内和日间精密度值（以 RSD% 表示）分别为 4% 和 7% (GC-FID)，以及 3% 和 6% (GC-MS)。信噪比 (S/N) 为 3 时的检测限 (LOD) 为 0.019 (GC-FID) 和 0.003 (GC-MS) g/kg；在 S/N = 10 下计算的定量限 (LOQ) 为 0.063 (GC-FID) 和 0.008 (GC-MS) g/kg，远低于橄榄油中发现的典型角鲨烯浓度水平。获得的百分比回收率为 70 ± 2 (GC-FID) 和 98 ± 3 (GC-MS)，并且与浓度无关。