Combined pulsed flame photometric ionization detector

The pulsed flame photometric ionization detector (PFPID) is designed for the simultaneous selective detection of molecules containing carbon, sulfur, phosphorus, or nitrogen atoms using gas chromatography (GC). The PFPID is based on a pulsed flame which propagates from the igniter through the ionization and photometric chambers consecutively. The flame is then self-terminated and reignited after a few hundred milliseconds in a pulsed periodic fashion. Since the pulsed flame photometer works with a hydrogen-rich atmosphere, the GC eluting molecules are predominantly pyrolyzed and only slightly combusted in the initial pulsed flame photometric chamber. These products are further combusted in the second pulsed flame ionization chamber, where the combustible gas mixture is separately optimized. The resulting electrons/ions are collected by an electrically isolated collector positively biased to 10 V. The addition of a pulsed flame ionization detector (PFID) to the pulsed flame photometric detector (PFPD) requires addition of negligible hardware (an isolated charge collector). It also requires the addition of a current-to-voltage converter and a double-gated instead of a single-gated amplifier for simultaneous PFPD-PFID work. The PFPID can be operated separately as either a pulsed FPD or a pulsed FID or simultaneously as both at the same H2/air gas flow rates. The simultaneous selective analysis of sulfur and organic compounds in gasoline, kerosene, and diesel fuel is demonstrated and discussed in terms of the various operational parameters. The performance of the PFPID is analyzed and compared to that of other sulfur and carbon simultaneous selective detection schemes.