亚麻籽油中不同构型反式亚麻酸的气相色谱测定方法Gas chromatographic determination method of trans-linolenic acid with different configurations in linseed oil

为了定量分析亚麻籽油中α-亚麻酸（ALA）顺反异构体，采用SLB-IL111色谱柱，对气相色谱法测定反式亚麻酸（TALA）的分析条件（载气流速和升温程序）进行优化，并对所建立的方法进行评价。结果表明：载气流速选择0.3 mL/min；升温程序为60 ℃保持5 min，以20 ℃/min升温至175 ℃保持15 min，以1 ℃/min升温至180 ℃保持28 min，以0.2 ℃/min升温至185 ℃保持40 min；该方法可实现9c,12t,15t-C18∶ 3和9t,12c,15t-C18∶ 3的较好分离，分离度为0.9，其余各TALA的分离度在1.6~8.7之间；所建立的方法重复性好，测定加热亚麻籽油样时各异构体日间相对标准偏差（RSD）为3.16%~5.65%，日内RSD为2.00%~4.13%，检出限为0.678 2~0.879 0 mg/L，定量限为2.260 6~2.930 1 mg/L；各ALA异构体含量与峰面积之间线性关系良好，相关系数均为0.999 8。综上，所建立的方法可用于亚麻籽油中8种不同构型ALA顺反异构体的定量分析。 In order to quantitatively analyze the cis- and trans- isomers of α-linolenic acid (ALA) in linseed oil, the analytical conditions (carrier gas flow rate and temperature program) for the determination of trans-linolenic acid (TALA) by gas chromatography were optimized on the SLB-IL111 column,and the established method was evaluated. The results showed that the optimal carrier gas flow rate was 0.3 mL/min, and the chromatographic column was initially heated at 60 ℃ for 5 min, then ramped at 20 ℃/min to 175 ℃ and held for 15 min, ramped at 1 ℃/min to 180 ℃ and held for 28 min, finally ramped at 0.2 ℃/min to 185 ℃ and held for 40 min. The method established had effective separation of 9c,12t,15t-C18∶ 3 and 9t,12c,15t-C18∶ 3 with a separation degree of 0.9. The separation degree of the other TALA ranged from 1.6 to 8.7. The method was reproducible and the relative standard deviation (RSD) of inter-day repetition of each isomer in heated lineseed oil was 316%-565%, and the RSD of intra-day was 200%-413%.The detection limit was 0.678 2-0.879 0 mg/L, and the limit of quantification was 2.260 6-2.930 1 mg/L. The linear relationship between the content of each ALA isomer and the peak area was good, and all the correlation coefficient was 0.999 8. In conclusion, the established method can be used for the quantitative analysis of 8 different isomer of ALA in linseed oil.