Agilent 6890 series gc

Essential oils were solubilized in acetone 1:100 v/v (Merck KGaA, Darmstadt, Germany). Chemical analysis of the essential oils was performed on an Agilent 6890 Series GC (Agilent, Santa Clara, CA, USA), interfaced with a 5973 Series quadrupole MS detector (Agilent, Santa Clara, CA, USA) and equipped with a DB-5MS column (30 m × 0.25 mm i.d. × 0.25 μm) (Agilent J&W, Santa Clara, CA, USA). Chromatography conditions were as follows; oven temperature program: 40 °C for 1 min with subsequent temperature increase of 3 °C/min up to 240 °C, keeping it at this temperature for 10 min.; carrier gas: He at a flow rate of 1 mL/min; injector and detector temperature of 250 °C; electron ionization: 70 eV. The component abundances were expressed as the mean ± standard deviation of the triplicates. The essential oil components were identified by comparing the retention indices (evaluated in relation to the retention times of a series of n-alkanes) and by comparison of their mass spectra with those reported in the literature [20 ,21 ].

After each treatment
(Table 1), the fabrics
were analyzed for PFAAs and volatile PFASs. PFAAs were extracted and
analyzed by the method earlier developed and described by Van der
Veen et al.^{38 (link)} In short, textile samples
of approximately 20 cm², cut in smaller pieces, were extracted
with methanol for the determination of PFAAs with an Agilent 6410
Triple Quad liquid chromatography-tandem mass spectrometer (LC-MS/MS,
Agilent Technologies, Amstelveen, The Netherlands) in the electrospray
negative ionization mode. For extraction and analysis of the volatile
PFASs, the method described by Van der Veen et al.^{27 (link)} was used. In short, textile samples of approximately 20
cm² were extracted with ethyl acetate. After cleaning the
extracts with Envi-carb and a concentrating step, the extracts were
analyzed with gas chromatography/electron impact-mass spectrometry
(GC/EI-MS) on an Agilent 6890 series GC coupled to a 5973 Network
MS (Agilent Technologies, Amstelveen, The Netherlands).

Liquid samples (1 ml) were collected from the influent and effluent of each reactor every 2–3 days, and were pelleted by centrifugation for 5 min at 16,000 × g. The supernatants were stored at −20 °C until further analyses. Nitrite concentrations were determined colorimetrically at 540 nm after a 20 min reaction of 1 ml sample with 1 ml 1% sulfanilic acid in 1 M HCl and 1 ml 0.1% N-naphtylethylenediamine^{23 (link)}. Ammonium concentrations were determined colorimetrically at 420 nm after a 30 min reaction of 40 µl sample with 760 µl 0.54% ortho-phthalaldehyde, 0.05% β-mercaptanol, and 10% ethanol in 400 mM potassium phosphate buffer (pH 7.3)^{23 (link)}. The nitrate concentrations were determined by a Sievers Nitric Oxide Analyzer 280i (Analytix Ltd, UK) according to the manufacturer’s instructions. The gas inlet and outlet of reactors II and III were connected to an Eco Physics CLD700 EL chemiluminescence NO_x analyzer (EcoPhysics, Switzerland) every 3–4 days to measure the concentration of NO. N₂O was measured at least once a week with an Agilent 6890 Series GC (Agilent Technologies, USA) equipped with a Porapak Q column and an electron capture detector (ECD).

An Agilent 6890 series GC (Agilent
Technologies, USA) equipped with a flame ionization detector (FID)
was used to determine the concentration of HCHs throughout the study.
Further analytical details are documented in S3 (SI).

Short chain fatty acid analysis was conducted according to a previously described method [43 (link)]. Samples were thawed, prepared by vacuum distillation, and analysed by gas chromatography (Agilent 6890 Series GC, Agilent Technologies, Wilmington, DE, USA), using a fused silica column (J&W Scientific, supplied by Agilent) with a 1 µm coating. Helium was the carrier gas (flow rate of 6 mL/min). Split injector and FID detector were held at 250 °C. The oven was held at 90 °C for 1 min, then ramped to 190 °C (rate of 10 °C/min) and held for 1 min. SCFA values were corrected to mmoles per gram DM weighed into the serum bottles prior to inoculation.
Ammonium analysis was carried out using a modified colorimetric method [44 (link)]. The method is based on the chemical reaction of NH₄⁺ ions with sodium salicylate and nitroprusside in a weakly alkaline buffer, at a wavelength of 650 nm, using a UV/visible spectrophotometer (Automated Discrete Analyser Model AQ2+, SEAL Analytical Ltd., Fareham, UK).