Part per quadrillion quantitation of pentaerythritol tetranitrate vapor using online sampling gas chromatography-mass...

The development of an online sampling method using programmable temperature vaporization gas chromatography with a mass spectrometer detector (PTV-GC/MS) for the analysis of trace pentaerythritol tetranitrate (PETN) vapor is presented. PETN degradation was minimized by optimizing the temperature and flow rates of the vapor sampling infrastructure. Validation of the online method was done using a previously published technique, vapor sampling with Tenax-TA thermal desorption tubes followed by analysis with a thermal desorption system coupled to a programmable temperature vaporization gas chromatograph with a micro-electron capture detector (TDS-PTV-GC/μECD). Trace PETN vapor was generated using state-of-the-art instrumentation known as the TESTbed, located at the US Naval Research Laboratory. For PETN vapor concentrations in the parts per trillion_volume (ppt_v) range, quantitative results from the TDS-PTV-GC/μECD consistently showed concentrations approximately double that measured by the online PTV-GC/MS method, indicating that sample loss due to additional exposure to the vapor sampling infrastructure occurs when using online sampling. Further utilization of the online PTV-GC/MS system allowed for the quantitation/semi-quantitation of PETN vapor concentrations as low as 260 parts per quadrillion_volume (ppq_v) with only 10 min of sampling time.