Quenching-resistant multiple micro-flame photometric detector for gas chromatography.

A multiple flame photometric detector (mFPD) based on many flames operated in series is introduced for the detection of sulfur and phosphorus compounds. The method employs attributes of a previously developed micro counter-current flame technique to readily establish any number of very small compact flames inside a narrow quartz tube. Results show for the first time that a five flame mFPD mode can improve hydrocarbon quenching resistance nearly 20-fold relative to a single flame (i.e., conventional FPD) mode, and nearly 10-fold relative to a two flame (i.e., dual FPD) mode. Under these conditions, the five flame mFPD mode is shown to maintain about 60% of its original analyte chemiluminescence even in the presence of over 100 mL/min of methane flow into the detector. In contrast to a conventional dual FPD device, the five flame mFPD mode also provides analyte sensitivity that is similar to a conventional FPD. Of note, the mFPD yields minimum detectable limits for sulfur and phosphorus of 4 x 10(-11) g S/s and 3 x 10(-12) g P/s respectively. Analyte selectivity over hydrocarbons, signal reproducibility, and response equimolarity are also improved in the mFPD, making it a potentially useful detector for applications in gas chromatography.