Ecological Archives E094-025-A2

Graham G. Frye, John W. Connelly, David D. Musil, Jennifer S. Forbey. 2013. Phytochemistry predicts habitat selection by an avian herbivore at multiple spatial scales. Ecology 94:308–314. http://dx.doi.org/10.1890/12-1313.1

Appendix B. Supplementary information on the quantification of monoterpene concentrations in sagebrush (Artemisia spp.) samples, including methods, materials, and a table of gas chromatograph retention times.

We quantified monoterpene concentrations in sagebrush samples with an Agilent 7694 headspace sampler coupled with an Aglient 6890N gas chromatograph (GC). One mL of headspace gas was injected into a J&W DB-5 capillary column (30m × 250µm × 0.25µm).

Operating conditions for the headspace sampler were: oven temperature at 100°C, loop temperature at 110°C, transfer line temperature at 120°C, a vial equilibrium time of 20 min, a pressurization time of 0.20 min, a loop fill time of 0.50 min, a loop equilibrium time of 0.20 min, and an injection time of 0.50 min.

Operating conditions for the GC were: splitless injector at 250°C, flame ionization detector at 300°C, oven temperature at 40°C for 2 min, then increasing 3°C/min to 60°C, then increasing 5°C/min to 120°C, then increasing 20°C/min to 300°C, and held at 300°C for 7 min. The make-up gas was nitrogen and the carrier gas was helium. The inlet pressure was 80 KPa with a flow rate of 1.0 mL/min.

Retention times and peak areas of individual monterpenes were calculated in HP ChemStation version B.01.00. Peak areas were calculated via integration of chromatogram curves. Compounds with peak areas greater than 2% of the total area were used in habitat-selection analyses, with the exception of camphor. Camphor concentrations were above the linear range of detection, potentially producing inaccurate measurements, and were thus excluded from the analysis. We identified monoterpenes via co-chromatography with known standards. Two monoterpenes were unidentified (unknown #1, unknown #7), but had peak areas exceeding 2% of total integrated chromatogram area.

TABLE B1. Headspace gas chromatography retention times (min) for monoterpenes considered during analyses of Greater Sage-Grouse (Centrocercus urophasianus) habitat selection in south-central Idaho, USA.

Monoterpene name

Retention time (min)

Unknown #1

3.28

α-pinene

13.81

Camphene

14.40

β-pinene

15.50

Cymene

17.29

1,8-cineole

17.57

Unknown #7

22.09


[Back to E094-025]