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Direct Supersonic Expansions of Supercritical Fluids for Analysis of Polycyclic Aromatic Hydrocarbons

Volume 41, Number 8 (Dec. 1987) Page 1392-1397

Goates, S.R.; Barker, A.J.; Zakharia, H.S.; Khoobehi, B.; Sheen, C.W.


Significant line-narrowing has been observed in the laser-induced fluorescence spectra of naphthalene and perylene in direct supersonic expansions of simple supercritical carriers such as CO2, N2O, and even SF6, under conditions which minimize aerosol and cluster formation. Clusters form readily in expansions of CO2 and N2O unless nozzle temperatures exceed about 200°C. Results with more complex carriers, such as n-pentane, are much poorer. Selective detection of perylene at a limit of 2 ng (S/N = 3) in a mixture of ten polycyclic aromatic hydrocarbons and in a coal tar extract has been achieved with a capillary introduction system. Challenges with coupling supersonic jet detection to capillary supercritical fluid chromatography lie with the nozzle.