Quenching-Resistant Multiple Micro-Flame Photometric Detector for Gas Chromatography

Abstract

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.

GC-MS Analysis of Volatile Plant Secondary Metabolites

“…The nitrogen and phosphorus selective detector (NPD) emits a selective response to all compounds with nitrogen or phosphorus in their structure (Amvrazy & Tsiropoulos, 2009). The flame photometric detector (FPD) releases a signal only in the presence of compounds with sulfur or phosphorus in their structure (Hayward & Thurbide, 2009). The atomic emission detector (AED) expands the domain of chemical elements that can be registered in the eluting substances, to the extent of performing their elemental analysis (Campillo et al, 2010).…”

Spectral examination of a multiple-flame photometric detector for use in chromatography

“…Most notably, the mFPD is comprised of several small flames burning in series that analytes travel through en route to the final analytical flame where the signal is monitored. This arrangement produces improved analytical sensitivity relative to conventional single-flame and dual-flame FPD modes 26 and also provides a very high resistance to hydrocarbon quenching and greatly enhanced response uniformity and reproducibility. 26,27 Most recently, a linear sulfur response mode has also been demonstrated in the mFPD.…”

“…This arrangement produces improved analytical sensitivity relative to conventional single-flame and dual-flame FPD modes 26 and also provides a very high resistance to hydrocarbon quenching and greatly enhanced response uniformity and reproducibility. 26,27 Most recently, a linear sulfur response mode has also been demonstrated in the mFPD. 27 Therefore, the mFPD can be a useful alternative tool in applications where conventional FPD performance may suffer from the above-noted difficulties.…”

“…While the performance attributes of the mFPD have been established, 26,27 very little is known about the actual mechanism through which the detector provides such response. For instance, at the most fundamental level, the identities of the emitting species in the analytical flame have never been confirmed and have only been assumed similar to those present in a conventional FPD flame.…”

“…Since this has not yet been done with the mFPD or the countercurrent flame that it operates in the analytical position, it can yield very valuable information on how it functions. Further, since the mFPD has been shown to provide a direct means of comparing multiple flame performance to that of a conventional single flame, 26,27 this device can also be used to obtain comparative spectra from both modes of operation under otherwise identical conditions. This paper presents the first ever spectral examination of the mFPD.…”