微波辅助甲酯化-快速GC法测定烟草中的多元酸和高级脂肪酸

建立了同时检测烟草中多元酸(草酸、丙二酸、反丁烯二酸、琥珀酸、苹果酸和柠檬酸)和高级脂肪酸(棕榈酸、硬脂酸和亚油酸)的微波辅助甲酯化-快速气相色谱(GC)分析方法,并测定了烤烟及雪茄烟各10个烟叶样品中的多元酸和高级脂肪酸含量(质量分数)。结果表明:①最优前处理条件为衍生化试剂10%硫酸-甲醇溶液,微波功率以20 W/s的速率升高至1200 W(保持1 min),萃取剂二氯甲烷。②快速GC分析时间为8.81 min,目标化合物标准曲线线性良好(r2>0.99),加标回收率在83.18%~114.17%之间,精密度(RSD)小于5%。③烤烟烟叶和雪茄烟烟叶中有机酸含量差异较大,其中烤烟烟叶中多元酸(除苹果酸外)含量低于雪茄烟烟叶,高级脂肪酸(除硬脂酸外)含量高于雪茄烟烟叶。该方法快速、准确,适用于测定烟草中的多元酸和高级脂肪酸含量。 

Determination of Polybasic Acids and Higher Fatty Acids in Tobacco by Microwave-assisted Methyl Esterification Combining with Fast GC

A method combining microwave-assisted derivatization with fast gas chromatography(GC) was developed for rapidly determining the contents of polybasic acids(oxalic acid,malonic acid,fumaric acid,succinic acid,malic acid and citric acid) and higher fatty acids(palmitic acid,stearic acid and linoleic acid) in tobacco,and the contents of these acids in ten flue-cured tobacco samples and ten cigar filler tobacco samples were determined.The results showed that:1) The optimal pretreatment conditions were using 10% sulfuric acid-methanol as esterification reagent and CH2Cl2 as extraction agent while the power of microwave increased at a rate of 20 W/s to 1200 W(remaining for 1 min).2) The time for fast GC analysis was 8.81 min,the calibration curves of target compounds displayed good linearity(r2>0.99),the standard addition recoveries ranged from 83.18% to 114.17% with RSD less than 5%.3) The contents of organic acids in flue-cured tobacco and cigar filler tobacco were quite different,the contents of polybasic acids(excluding malic acid) were higher in cigar filler tobacco,while the contents of higher fatty acids(excluding stearic acid) were higher in flue-cured tobacco.This method is rapid,accurate and suitable for the determination of polybasic acids and higher fatty acids in tobacco.