HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY (HPLC) OF COAL-LIQUEFACTION PROCESS STREAMS USING NORMAL-PHASE SEPARATION WITH DIODE-ARRAY DETECTION

A method is described for a normal-phase separation and quantification of polynuclear aromatic hydrocarbons (PAHs) using high performance liquid chromatography (HPLC) coupled with UV-diode array detection. The method employed takes advantage of the inherent capabilities of a ''charge-transfer'' normal-phase HPLC column (Holstein, W. Chromatographia 1981, 14, 468), the Hypersil PAH-2 column (Keystone Scientific, Inc., Bellefonte, PA), and the ability of the diode array detector to provide UV spectra for each eluting compound having chromophores in the UV range which allows for separation, identification, and quantification in the normal phase of individual PAHs. Elaborate sample preparations, which in the past have accompanied determination and separation of individual PAHs, can be avoided for the analysis of PAHs in either extracts of natural samples or complex fuel mixtures. The potential for this method was demonstrated by the separation and quantification of five well-studied coal liquefaction process stream samples. PAHs having from two rings up to nine rings, along with their isomers and alkylated derivatives, were separated and quantified using this method. Clear differences were observed among liquefaction process streams due, in large part, to differences in feed coals and process conditions,