Evaluation of on-line pyrolysis two-dimensional gas chromatography time-of-flight mass spectrometry (Py-GC × GC-ToFMS) on whole sediments from a Mediterranean sapropel sequence

► GC × GC-ToFMS was used to analyze molecular fragments from whole-sediment pyrolysis. ► GC × GC increases peak capacity and detectability and yields patterned chromatograms. ► Different pyrolysis products were obtained from sapropels and non-sapropels. ► Pyrolysis temperature and GC columns must be optimized for best results.