Accurate quantitation of pentaerythritol tetranitrate and its degradation products using liquid chromatography–atmospheric pressure chemical ionization–mass spectrometry

•LC–MS method developed for traces of the explosive pentaerythritol tetranitrate.•Custom-made standards of PETN degradation products for accurate quantitation.•Post-explosion PETN can be distinguished from naturally degraded PETN.•Crime-scene presence can be reliably established. After an explosion of pentaerythritol tetranitrate (PETN), its degradation products pentaerythritol trinitrate (PETriN), dinitrate (PEDiN) and mononitrate (PEMN) were detected using liquid chromatography–atmospheric-pressure chemical-ionization–mass spectrometry (LC–APCI–MS). Discrimination between post-explosion and naturally degraded PETN could be achieved based on the relative amounts of the degradation products. This information can be used as evidence when investigating a possible relationship between a suspect and a post-explosion crime scene. The present work focuses on accurate quantitation of PETN and its degradation products, using PETriN, PEDiN and PEMN standards specifically synthesized for this purpose. With the use of these standards, the ionization behavior of these compounds was studied, and a quantitative method was developed. Quantitation of PETN and trace levels of its degradation products was shown to be possible with accuracy between 85.7% and 103.7% and a precision ranging from 1.3% to 11.5%. The custom-made standards resulted in a more robust and reliable method to discriminate between post-explosion and naturally-degraded PETN.