Properties of Erythritol Tetranitrate from Molecular Dynamics Simulation

The nonpolarizable force field for alkyl nitrates developed by Borodin et al. [J. Phys. Chem. B, 2008, 112, 734-742] has been employed to calculate selected properties of crystalline and liquid erythritol tetranitrate (ETN). The set of partial charges proposed by Borodin for pentaerythritol tetranitrate (PETN) was used except for a small correction to the H atom charges to ensure charge neutrality owing to the absence of the neopentyl carbon in ETN. The force field was used to compute the isothermal compression curve, lattice parameters, heat capacity, thermal expansivity, single crystal elastic constants, and Gruneisen parameters of crystalline ETN. The density- and temperature-dependent viscosities of liquid ETN are also reported. We anticipate that these data will be of some utility to the development of equations of state and thermomechanical models for ETN.

Comprehensive two-dimensional gas chromatography under low-pressure conditions

The analysis of thermally labile and high-boiling point compounds by gas chromatography (GC) can be a challenge. One technique to overcome these challenges is low-pressure GC, which uses the vacuum produced from the mass spectrometer and wide-bore columns to elute compounds at significantly lower temperatures. While GC-MS is a powerful technique, comprehensive two-dimensional gas chromatography (GC × GC), allows for resolution of compounds that would typically coelute using GC. In this study, a pesticide standard mixture (8270 MegaMix Standard) was analyzed using a conventional GC × GC-TOFMS configuration (0.25 mm inner diameter (i.d.) to a 0.18 mm i.d. column) and low-pressure GC × GC-TOFMS configuration (0.53 mm i.d. to a 0.53 mm i.d. column). Elution temperatures, sensitivity, and peak capacity were investigated for both configurations. Compounds eluted an average of 30 °C less on the low-pressure GC × GC-TOFMS configuration compared to the conventional GC × GC-TOFMS configuration. Moreover, the compounds were separated in ∼13 min on the low-pressure GC × GC-TOFMS as opposed to 33 min for conventional GC × GC-TOFMS. However, due to the wide-bore columns and faster runtimes the low-pressure GC × GC-TOFMS had a lower, β corrected 2D peak capacity, nc,β,2D, of 1260 while the conventional GC × GC-TOFMS was 3588. Interestingly, both configurations yielded a similar peak capacity production of 93 peaks/min and 107 peaks/min for low-pressure and conventional GC × GC-TOFMS, respectively. A "real world" sample of diesel fuel was tested on the low-pressure and conventional GC × GC-TOFMS configurations and similar results were obtained compared to the pesticide standard mix except the peak capacity production of the low-pressure GC × GC-TOFMS configuration was higher than that of the conventional GC × GC-TOFMS method.