H-E1 (aged voucher material)
(University of New England)
A small sample of dried leaf material (~0.02g) was removed from herbarium vouchers maintained at the N.C.W. Beadle Herbarium (University of New England, Armidale) and placed in glass vials containing ~ 1 mL MeOH. Material was left to extract overnight as a minimum (up to 2 days) and sonicated for 80 min. Extracts were filtered and diluted with further MeOH as necessary. Batches were injected into the GC-MS in batches for characterization, or frozen until characterization.
Agilent GC System 7890A; inert MSD with triple-axis detector 7975C; Agilent HP-5MS column (30 m × 250μm× 0.25μm; He; 50 °C for 0 min, 5 °C/min to 260 °C, hold 2 min). To limit the impact of solvent-related peaks, peaks prior to a retention time of 3.5 min were not considered in analyses.
Spectra were matched to the NIST11 library and a small private Eremophila compound library maintained at the University of New England. The top 10 peaks were selected, and arithmetic (retention) indices (AI) calculated and compared to the NIST Webbook (http://webbook.nist.gov/chemistry/). An annotation was rejected if the AI (+/-2%) did not match published values for nonpolar column data. If the quality match of the spectra to the NIST11 or private library was under 80% the annotation was rejected. Where no published AI was available, a compound was accepted if the quality of the spectra match was 90% or over.