The development of two-dimensional gas chromatography introduced the possibility to provide reliable compositional information on middle distillate refinery streams such as jet fuel and diesel. The original GCxGC systems mainly relied on cryogenic modulation, which is effective but has some analytical challenges and downsides for routine laboratory use. The most common are:
• High cost of ownership due to the large consumption of liquid CO2 or liquid Nitrogen.
• Requires a lot of lab space.
• Cryogenic modulation is maintenance intensive.
• Low boiling point components are hard to trap and may break through the cryogenic trap.
The challenge that flow modulation presents method developers is in optimising application parameters such as column length, column phase, column flows and GC oven programming to achieve the desired separations. However, once the right parameters have been determined, flow modulation rewards the operator with a lower cost, lower maintenance, and easier to use GC x GC application which also eliminates low boiler breakthrough issues common to the cryogenic trap.
AC Analytical Controls BV (AC) (Netherlands) has solved this analytical challenge and has developed a ready to use flow modulated GC x GC application that provides a complete group-type analysis of jet fuel and diesel fuel streams, including biodiesels blends such as B5, B7 and B10. In addition to the commonly required paraffin (P), naphthene (N) and aromatic (A) species and group results, additional information about the speciated and total Fatty Acid Methyl Esters (FAME) content is reported for biodiesel blends.
This article describes the basic configuration for this AC GC x GC application, and provides information regarding group-type separation and the used quantification method. In addition, we describe how the quantitation results of the application are validated for jet fuel and diesel samples by comparing the values found using the GC x GC method with existing CEN methods for the determination of Total Aromatics and Total FAME content in the applicable products.
