Hydrocarbon class analysis of coal-derived liquids using high performance liquid chromatography

A normal-phase HPLC analysis method has been developed to separate coal-derived liquids into six compound classes: aliphatics, 1-ring aromatics, 2-ring aromatics, 3-ring aromatics, 4-ring aromatics and polars. Three columns were used for the separation. A UV photo-diode-array detector was used for compound-class identification and an evaporative-light-scattering detector was used for quantitative analysis of compounds with boiling points > 600 degrees F (315 degrees C). Quantification methods with the evaporative-light-scattering detector are discussed in detail. A power-law model was found to mathematically describe the relationship between sample concentration and detector signal. Constants were determined for optimized detector conditions with pentane and methylene chloride mobile phases. Agreement between GC-simulated-distillation results and total mass detected in compound-class separations are excellent.