基于科瓦茨保留指数的同分异构体气相色谱分析OA

Due to their identical molecular compositions and slight structural differences,isomers often face separation difficulties and qualitative errors in gas chromatographic(GC)analysis.The Kovats Retention Index(KRI),a dimensionless chromatographic qualitative parameter,can effectively eliminate the influence of fluctuations in chromatographic conditions on retention time,thus becoming an important basis for the qualitative analysis and separation of isomers.In this study,the calculation principles and prediction methods of KRI,as well as the influence of different chromatographic column stationary phases and temperature programming on the retention index of xylene and diisopropylbenzene isomers,were systematically investigated.The experimental results showed that on the polar column(DB-FFAP),the KRI differences of the xylene isomers ranged 17～35,whereas those of the diisopropylbenzene isomers ranged 31～68.These differences were significantly larger than those observed on the non-polar column(13,14,and 9～19,respectively).The polar column effectively amplified the retention differences through dipole-dipole and hydrogen bonding interactions,enabling baseline separation.This study clarified the peak order determination and separation optimization strategies for isomers based on the retention index and provided standardized guidance for the qualitative GC analysis of organic isomers.