Parallel reaction monitoring (PRM) is an ion monitoring technique for relative and absolute quantification of target peptides based on high-resolution mass spectrometry. Every peptide has its own unique fingerprint, based on a signature fragmentation spectrum (m/z and relative intensities of fragment ions), precursor m/z and retention time profile. The principle of this technique is comparable to SRM/MRM on e.g. triple quad mass spectrometers, but it is more convenient in assay development and more accurate in fragment ion selection. It is suitable for quantification of multiple (usually several 10s to 100s per LC-MS run) peptides in complex samples at the low- to mid-attomole level detection.
Examples of applications of PRM: