Zebron zb 1 capillary column

For chlorine isotope analysis a multi collector-inductively coupled plasma mass spectrometer was coupled to gas chromatography (GC-MC-ICPMS) (Horst et al., 2017 (link)). The MC-ICPMS, a Neptune (Thermo Fisher Scientific, Germany), was equipped with a gas chromatograph Trace 1310 (Thermo Scientific, Germany) coupled to FID. Triplicate samples were analyzed by manual injection of 0.05–1 mL headspace with a split ratio of 1:10 with injector kept at 250°C and a carrier gas flow of 2 mL⋅min^–1. For the analysis, a Zebron ZB-1 capillary column (60 m × 0.32 mm i.d., 1 μm film thickness; Phenomenex Inc.) was utilized isothermal at 100°C for 1,2-DCA, VC and cis-DCE and 120°C for PCE analysis. The separated compounds were transferred to the plasma via a Thermo Electron TransferLine (AE2080, Aquitaine Electronique, France) heated to 250°C using an auxiliary helium flow of 5 mL⋅min^–1. Instrument tuning and preparation was performed daily prior to the measurements (Horst et al., 2017 (link)). Chlorine isotope ratios were determined relative to the laboratory standards [methyl chloride, TCE-2, and TCE-6 (Horst et al., 2017 (link); Renpenning et al., 2018 (link))]. The overall analytical uncertainty was <0.5%.

The soluble carbohydrates were analyzed using a high-resolution gas chromatography method described previously [93 (link)]. Briefly, sugars were extracted from 40–42 mg of dry pulverized tissues with 50% ethanol containing xylitol as the internal standard. After heating (at 90 °C for 30 min), the homogenate was centrifuged (20,000× g for 20 min at 4 °C) and aliquots of clear supernatant were filtered using micro-spin filters (PVDF, 0.2 μm, Thermo Fisher Scientific, Loughborough, UK). A part of the filtrate was evaporated to dryness in a speed vacuum rotary evaporator (JW Electronic, Warsaw, Poland). Carbohydrates were derivatized with a mixture of trimethylsilyl imidazole and pyridine (1:1, v/v), and TMS derivatives of soluble carbohydrates were analyzed in a gas chromatograph (GC 2010, Shimadzu, Japan) equipped with a Zebron ZB-1 capillary column (15 m length, 0.25 mm diameter, 0.1 μm film, Phenomenex, Torrance, CA, USA) and flame-ionization detector, at conditions described earlier [98 (link)]. Carbohydrates were quantified by using original standards of glucose, fructose, galactose, sucrose, maltose, maltotriose, 1-kestose, MIN, DCI and PIN (purchased from Sigma-Aldrich, Saint Louis, MO, USA).