The improved inertness for polar analytes was the inspiration for the development of SLB®-IL (i-series) ionic liquid capillary GC columns. They solve a dilemma that has existed for a long time; is it better to optimize for selectivity or inertness? With i-series columns, GC users can enjoy selectivity and inertness! 
 
By providing both selectivity and inertness towards polar analytes, better accuracy and sensitivity can be achieved. When comparing the chromatography of two analytes with similar boiling points: 

 

1. SLB-IL (i-series) columns combine high selectivity for polar analytes and high inertness towards polar analytes, so provide resolution and good peak shapes for both analytes 
   
2. Traditional highly polar columns, with high selectivity for polar analytes and low inertness towards polar analytes, provide resolution, but a poor peak shape for the polar analyte 
   
3. Traditional non-polar columns have low selectivity for polar analytes and high inertness towards polar analytes, so provide good peak shapes for both analytes, but limited resolution 
   

 
It is advantageous to have columns with alternative selectivities at hand, because resolution is greatly affected by selectivity. A range of i-series columns were developed and classified as polar (SLB-IL60i), highly polar (SLB-IL76i), and extremely polar (SLB-IL111i).