高效液相色谱-荧光衍生法快速测定地沟油中的长链脂肪醛

本研究利用地沟油精炼过程中会产生醛类化合物的特点, 以O-(3-(9H-咔唑-9-基)丙基)羟胺为荧光衍生化试剂, 采用高效液相色谱法测定己醛、庚醛、辛醛、壬醛、癸醛5种长链脂肪醛来鉴别地沟油及食用油中是否掺杂地沟油. 10 μL待测油样品溶于200 μL异丙醇, 在最佳条件下与O-(3-(9H-咔唑-9-基)丙基)羟胺反应生成稳定的衍生物, 乙腈萃取后进样分析.以乙腈-水(90∶10, V/V)为流动相, 在λex /λem=292 nm/348 nm下荧光检测, 衍生物在C18柱上15 min内可完全分离.检测5种脂肪醛的线性范围均为0.01~1.00 μmol/L, 检出限为0.05~0.10 nmol/L, 加样回收率为95.6%~101.4%.待测油样品的测定结果表明, 食用油基本不含上述5种脂肪醛, 而精炼地沟油中5种脂肪醛含量显著增加, 因此5种脂肪醛含量可作为检测地沟油的指标.本方法专属性强、灵敏度高、准确性好,方便,快捷, 可用于快速检测地沟油.

Rapid Determination of Long-chain Aliphatic Aldehyde in Gutter Oil by Fluorescent Derivatization-High Performance Liquid Chromatography

Reuse of waste oil in cooking has been the social concern for long time, but until now there is no reliable method to identify the gutter oil.In this work, based on the generation of long-chain aliphatic aldehydes in the refinement of gutter oil, gutter oil and adulterate cooking oil were identified by determining hexanal, heptanal, octanal, nonanal and decanal in oil sample with high perfomance liquid chromatography (HPLC) method using O-(3-(9H-carbazol-9-yl)propyl)hydroxylamine as the fluorescent derivative reagent.At first, 10 μL of oil sample was dissolved in 200 μL of isopropanol, then reacted with O-(3-(9H-carbazol-9-yl)propyl)hydroxylamine to form the stable derivatives, extracted with acetonitrile and injected into HPLC for analysis.The derivatives were separated on a C18 column within 15 min with ACN-H2O (90∶10, V/V) as mobile phase.The fluorescence detector was set at λex/λem=292 nm/348 nm.The linear range of 5 kinds of long-chain aliphatic aldehydes was 0.01-1.00 μmol/L with limit of detection (LOD, S/N=3) of 0.05-0.10 nmol/L, and the spiked recoveries were 95.6%-101.4%.The results showed that the edible oils obtained from supermarket almost had no hexanal, heptanal, octanal, nonanal, decanal, but these aldehydes increased significantly in gutter oil.Thus the 5 kinds of long-chain aldehydes could be used as the indictor of gutter oil.Taking the advantage of good specificity, higher sensitivity, good accuracy and simplicity, the method was suitable for the rapid identification of gutter oil.