Regioisomeric Characterization of Triacylglycerols Using Silver-Ion HPLC/MS and Randomization Synthesis of Standards
作者:Miroslav Lísa、Hana Velínská、Michal Holčapek
DOI:10.1021/ac900150j
日期:2009.5.15
Silver-ion normal-phase high-performance liquid chromatography (HPLC) provides a superior separation selectivity for lipids differing in the number and position of double bonds in fatty acid chains including the resolution of triacylglycerol (TG) regioisomers under optimized conditions. Our silver-ion HPLC method is based on the coupling of three columns in the total length of 75 cm and a new mobile phase gradient consisting of hexane−acetonitrile−2-propanol which provides better resolution and also reproducibility in comparison to previously used mobile phases. In our work, the chemical interesterification (randomization) of single-acid TG standards is used for the generation of regioisomeric series of TGs, because it provides a random distribution of fatty acids in TGs at well-defined concentration ratios. The baseline separation of regioisomeric TG pairs containing up to three double bonds and the partial separation of TG regioisomers with four to seven double bonds are reported for the first time. Our silver-ion high-performance liquid chromatography/mass spectrometry (HPLC/MS) method is applied for the regioisomeric characterization of complex samples of plant oils and animal fat, where the results clearly demonstrate different preference of sn-2 occupation in plants (mainly unsaturated fatty acids) versus animal fat (mainly saturated fatty acids).
银离子正相高效液相色谱(HPLC)为脂质提供了优越的分离选择性,这些脂质在脂肪酸链中双键的数量和位置上存在差异,包括在优化条件下对甘油三酯(TG)位置异构体的分辨。我们的银离子HPLC方法是基于三根总长度为75厘米的柱子耦合以及一个新的由己烷、乙腈和丙酮醇组成的移动相梯度,这相比于之前使用的移动相提供了更好的分辨率和重复性。在我们的工作中,利用单酸TG标准的化学酯交换(随机化)来生成TG的位置异构体系列,因为这可以在明确定义的浓度比下提供脂肪酸在TG中的随机分布。首次报道了含有最多三个双键的位置异构体TG对的基线分离以及含有四到七个双键的TG位置异构体的部分分离。我们的银离子高效液相色谱/质谱(HPLC/MS)方法应用于植物油和动物脂肪的复杂样品的位置异构体特性鉴定,结果清楚地展示了在植物(主要是不饱和脂肪酸)和动物脂肪(主要是饱和脂肪酸)中sn-2占位偏好的不同。