PFPD vs. FPD
Posted: Tue Oct 26, 2010 6:36 am
by thohry
Hi all,
I know the principle of FPD detector. But recently see the term PFPD meaning Pulsed Flame Photometric Detector. So what is the 'pulsed' here ?
Thanks
Posted: Wed Oct 27, 2010 1:10 pm
by AICMM
thory,
The PFPD keeps the fuel/air ratio below that needed to maintain a constant flame. Then you leave the ignitor on all the time. This results in a build up of flammable gases followed by ignition and propagation but not sustained. Pop. The pop results in excited state species for sulfur or phosphorous (or others) that then emit, similar to an FPD. The emission of the sulfur is delayed relative to the emission of the carbon species. If you take advantage of the delay and only measure the signal in the time window of the sulfur emission you can increase your sensitivity and selectivity.
The main disadvantage is you get about 3-5 pops per second so you are rate limited on the data collection. This limits the ability of the PFPD to be used with narrow peaks or high speed GC.
Those are the basics....
Amirav has lots of articles in Analytical Chemistry for your review.
Best regards,
AICMM