Group-type characterisation of mineral oil samples by two-dimensional comprehensive normal-phase liquid chromatography–gas chromatography with time-of-flight mass spectrometric detection

Normal-phase liquid chromatography (NPLC) and capillary gas chromatography (GC) are complementary techniques, which makes them ideally suited for hyphenated and comprehensive coupling. In this work, an LC and a GC equipped with a time-of-flight mass spectrometer were on-line and comprehensively coupled (LC × GC–ToF MS) for the analysis of mineral oil samples. Classes of compounds present in the oil like paraffins, mono-aromatic and multi-aromatic compounds were separated by normal-phase LC, with a subsequent boiling-point separation within each class by means of GC. Sub-groups present in each class of compounds were distinguished by selecting their unique masses.