Pulsed Flow Modulation
Comprehensive two dimensional GCxGC improves the separation of GC. However, it suffers from complexity and high cost of purchase and cooling gases. In addition, GCxGC-MS is perceived to be limited to time of flight MS due to the need of fast scan speed for its narrow peaks.
We developed a novel method and device named pulsed flow modulation (PFM) for obtaining GCxGC and GCxGC-MS with supersonic molecular beams based on quadrupole mass analyzer (Supersonic GC-MS), and without any added gas.
Sample compounds which elutes from the first GC column are temporarily stored for a few seconds in a fused silica transfer line and are pulsed periodically injected by ~25 ml/min He gas pulse into the second column while simultaneously temporarily stopping the first column flow. After the pulse, 20 ml/min He develops the chromatography in the second column for a few seconds. The PFM is a simple and reliable device that does not require any added gas. The injection time can be tuned, it is easily compatible with the Supersonic GC-MS with quadrupole mass analyzer, and the increased PFM flow rate is handled by the nozzle chamber differential pumping. Thus, PFM-GCxGC in combination with the Supersonic GC-MS provides a unique combination of improved separation and mass spectral information.
A. All the Standard GCxGC Advantages of increased GC separation capability, improved sensitivity via narrower GC peaks, improved sensitivity via reduced matrix interference and group type sample information.
