The potential of quantitative pyrolysis-mass spectrometry is illustrated by two environmental applications of pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and in-source temperature-resolved pyrolysis-mass spectrometry (Py-MS). Py-GC-MS combined with selected ion monitoring (SIM) can give low-ppb detection limits for chlorolignosulphonic acids, which are high-molecular-mass industrial contaminants in river water. Py-MS was used to quantitatively analyze sulphonic acid groups in macromolecular dissolved organic matter (DOM).