7890a oven

GC-MS analysis was performed using a Pegasus 4D time-of-flight mass spectrometer (LECO) equipped with a Gerstel MPS2 autosampler and an Agilent 7890A oven. In the GC step, derivatization products were separated on an Rxi-5Sil^® column (30m, 0.25mm i.d., 0.25µm df) with an IntegraGuard^® pre-column using ultrapure helium at a constant flow of 0.9mL/minute as carrier gas. A split injection and injector port temperature of 240°C were employed, while the transfer line was set at 280°C. A 1µL sample volume was injected at an appropriate split ratio. The linear temperature gradient for GC started with a one-minute hold of the GC column at oven temperature of 70°C, which was then ramped at 10°C/minute to a final temperature of 300°C. Isothermal heating at 300°C was maintained for 5 minutes, followed by a final ramp to initial conditions. In the MS step, mass spectra were obtained using electron impact ionization at 70eV and a scan rate of 17 spectra/sec. Peak alignment and spectrum comparisons were carried out using the Statistical Compare feature of the ChromaTOF^® software (LECO).

Analyses were performed using a Pegasus 4D time-of-flight mass spectrometer (LECO) equipped with a Gerstel MPS2 autosampler and an Agilent 7890A oven. Derivatization products were separated on a (30 m × 0.25 mm i.d. ×0.25 μm) Rxi^®-5Sil column (Restek) with an IntegraGuard^® pre-column using ultrapure He at a constant flow of 1 mL min^–1 as carrier gas. The linear thermal gradient started with 1 min at 50°C, followed by a ramp to 330°C at 20°C min^–1. Final temperature was held for 5 min prior to returning to initial conditions and mass spectra were collected at 17 spectra s^–1. The injection port was held at 250°C, and an aliquot of the sample (1 μL) was injected.