Pulsed Flow Modulation GCxGC and GCxGC-MS

GCxGC and quadrupole GCxGC-MS without cooling consumables

Aviv Amirav, Marina Poliak, Maya Kochman, Alexander Fialkov, Uri Keshet and Tal Alon. (July 2015)

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 invented [1] and developed [2, 3] 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 (GC-MS with Cold EI), 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 GC-MS with Cold EI quadrupole mass analyzer, and the increased PFM flow rate is handled by the nozzle chamber differential pumping. Thus, PFM-GCxGC-MS with Cold EI provides a unique combination of improved GC separation and ultimate mass spectral information.

PFM-GCxGC is also useful for standard GC-FID and it is available by Agilent through their collaboration with John Seeley under the name of differential flow modulation and it is available by Aviv Analytical in combination with its 5975-SMB GC-MS with Cold EI.

Benefits of PFM GCxGC-MS with Cold EI

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.

B. Pulsed Flow Modulation Unique Advantages of elimination of added (cryogenic) gas requirement, simple to use and robust GCxGC modulator, low cost of the PFM device, extended sample capacity and LDR and built-in back-flush capability.

C. PFM GCxGC-MS with Cold EI unique advantages of enhanced molecular ion and isomer MS information, unlimited column flow rate acceptance, extended column sample capacity, ultra-fast ion source response time, GCxGC-MS with the robust quadrupole mass analyzer and GCxGC-SMB-MS-MS for ultimate selectivity/sensitivity.

For further information on our pulsed flow modulation please read:

1.  A. Amirav, "Pulsed Flow Modulation Gas Chromatography Mass Spectrometry with Supersonic Molecular Beams Method and Apparatus", Israel patent number 176724 and US Patent number 7,518,103. First submission date is June 2006.

2.  M. Poliak, M. Kochman, A. Amirav, "Pulsed Flow Modulation Comprehensive Two Dimensional Gas Chromatography", J. Chromatogr. A 1186, 189-195 (2008).

3. M. Poliak, A. B. Fialkov and A. Amirav "Pulsed Flow Modulation Comprehensive Two-Dimensional Gas Chromatography Tandem Mass Spectrometry with Supersonic Molecular Beams" J. Chromatogr. A. 1210, 108-114 (2008)   

4.  Aviv Amirav, Tal Alon, Uri Keshet and Alexander Fialkov,  "Pulsed Flow Modulation GCxGC-MS with Cold EI – The Emergence of Novel Concept of GCxGCxMS" Advanced GC-MS Blog Journal 2013

5.  Uri Keshet, Tal Alon, Paulina Goldshlag and Aviv Amirav, "Pesticide Analysis by Pulsed Flow Modulation GCxGC-MS with Cold EI – An Alternative to GC-MS-MS"  Advanced GC-MS Blog Journal 2013.  


I will be happy to Email papers 2 and/or 3 in pdf files upon request while the detailed articles in the Advanced GC-MS Blog Journal are linked above. 

For any question on the pulsed flow modulation GCxGC and GCxGC-MS please contact me through my E-mail:  amirav@tau.ac.il