Rt msieve 5 a

Water samples for dissolved gas composition were taken simultaneously with water chemistry and isotope samples, collected using the inverted bottle method³⁹ in 12 ml glass bottles capped with precision seal silicone septa caps. All samples were refrigerated until analysis at the University of Calgary. Dissolved gas compositions were determined by gas chromatography using headspace extraction. Due to our primary interest in CO₂ gas in this system, we used a headspace to sample water ratio of 3:1 and shaking time of 12 min at 400 rpm^{40 (link)}. Headspace samples were injected onto an HP 5890 (Hewlett-Packard) gas chromatograph with a Hamilton gas-tight syringe via a six-port, two-position sampling valve. The gas chromatograph was outfitted with parallel Rt-Msieve 5 A (Restek, 30 m × 0.32 mm) and Rt-Q-PLOT (Restek, 30 m × 0.53 mm), and data were collected using an HP 3396 Series II Integrator (Hewlett-Packard).

ET content was determined according to López-Gálvez et al. (2015) (link). A gas chromatograph with flame ionization detector was used (GC-FID) (Finnigan Trace GC Ultra, Thermo Fisher Scientific, Waltham, United States) equipped with the columns15 m/0.53 mm/RT-MSieve 5A (Restek, Bellefonte, United States), 30 m/RTU-Piot (Restek), and 25 m/0.53 mm/CP-PoraBOND Q Fused Silica (Varian, PaloAlto, United States). After calibration of the equipment, samples (∼1 mL) of headspace from weighed chopped material were injected into the column using a gas syringe. The GC oven was set at a constant temperature of 35°C, the carrier gas was helium and the FID used pressurized hydrogen and air. The software Thermo Finnigan Chrom Card32-bit was used to interpret the results.