Comparison of pressurized liquid extraction with classical solvent extraction and microwave-assisted extraction–application to the investigation of the artificial maturation of Mahakam coal

The pressurized liquid extraction (PLE) technique is validated by the comparison with microwave-assisted extraction and classical solvent extraction of the artificial maturation series of Mahakam coal. PLE extraction can greatly enhance the extraction of asphaltenes and resin under favorable conditions (fine sample dispersion and high extraction temperature). The stability of the thermolabile biomarkers is demonstrated at temperatures up to 100 °C during the PLE process. The molecular maturation indexes derived from the GC–MS analysis of extracts show no significant dependence on the extraction techniques.