Pulsed flame photometric detector - a step forward towards universal heteroatom selective detection

Pulsed flame photometric detector (PFPD) is characterized by the added information available from flame chemiluminescence emission time dependence. We have found that many elements possess unique delayed emission, whose time dependence can serve for their identification. Since carbon emission is fast and confined to the pulsed flame propagation time across the observation window, the heteroatom delayed emission can be separated in time from that of carbon, resulting in a substantial enhancement in the detection sensitivity and selectivity. For elements with delayed emissions, the PFPD is found to be superior to the conventional FPD in heteroatom detection sensitivity, selectivity against carbon and inter-heteroatom selectivity. Semi-universal heteroatom selective detection is described and illustrated in this paper with 28 elements including carbon. Among all the elements studied, the following elements show unique time-delayed emissions: S, P, N, As, Se, Sn, Ge, Ga, Sb, Te, Br, Cu and In, which enables their specific detection with respect to hydrocarbons. All the other detectable elements including Mn, Fe, Ru, Ph, Cr, Ni, Eu, V, W, B, Si, Al, Pb, Pi and C, show undelayed emissions, and can be selectively detected by the PFPD with a range of sensitivities, and heteroatom against carbon selectivities. The observed sensitivities and selectivities for all the 28 elements that were studied are tabulated and presented. Detailed experimental conditions and analysis data, including pulsed flame emission spectra, pulsed flame emission time dependence. compound used, as well as the chromatographic behavior for each element is provided so that this paper can serve as a comprehensive guiding tool for the universal detection of these elements with the PFPD. The PFPD analysis of methylcyclopentadienyl manganese tricarbonyl as Mn additive in gasoline is shown. In addition, simultaneous heteroatom selective detection and speciation, using a dual-gate response ratio method, is illustrated with a mixture of compounds containing S, Se, As, P, Ge and N atoms. (C) 1998 Elsevier Science B.V.