Py-GC-MS in organic geochemistry of petroleum systems: A systematic and critical review of methods, applications and trends

Pyrolysis coupled to gas chromatography and mass spectrometry (Py-GC-MS) is a promising analytical approach for molecular-level characterization of sedimentary organic matter and petroleum systems, providing information on kerogen structure, potential hydrocarbon generation, and oil–source rock relationships. This work presents a systematic review of Py-GC-MS applications in petroleum organic geochemistry between 1975 and 2025, following PRISMA guidelines, based on searches in five databases and 83 eligible studies. For the first time, we comprehensively map and discuss the matrices, pyrolysis modes, sample-preparation protocols, and analytical configurations reported in the literature. We observe a concentration of studies on bituminous shales and kerogens, with more limited use in carbonate rocks, and crude oils, as well as a geographic bias toward China, North America, and Europe. Rapid-heating Py-GC-MS at 600–650 °C is dominant, whereas Curie-point and sequential/multi-shot approaches occupy specialized niches for targeting kinetically distinct fractions and bound biomarkers. Our critical assessment highlights persistent gaps in standardized workflows, quantitative validation, and transparent reporting of experimental parameters. By synthesizing information on matrices, pyrolysis modes, and analytical choices, this review provides a clearer picture of consolidated applications, limitations, and critical parameters, a necessary step for Py-GC-MS to move beyond predominantly exploratory use and become a robust, predictive tool in the characterization of petroleum systems.