Agilent 7820a gc

Visit 2 and 4 involved 65 min of exercise, with an overall target exercise intensity of ~75% $$\dot{\mathrm{V}}$$ O_2max, designed to elicit muscular oxidative stress [45 (link)]. Participants completed a 5 min warm-up at a speed corresponding to LT1. Exercise intensity then increased to speeds that corresponded with 60% of the difference between LT1 and LT2 (∆LT1-LT2) for 50 min, before completing a maximum of 5 × 1 min intervals at a speed 10% above LT2, interspersed with 1 min active recovery at 60% ∆LT1-LT2. B[La], HR and RPE were measured at rest, and at 10, 30 and 48 min, and following the last interval. Exercise intensity was consistent between visit 2 and 4. Additionally, as a means to quantify whether the nutritional intervention influenced plasma HT (as the main polyphenol in OliP), resting whole blood measures were undertaken prior to both visit 2 and 4 (as part of a larger study reported elsewhere [45 (link)]). For this, whole blood samples were collected into 4 mL Vacuette™ K2EDTA tubes (Greiner Bio-One GmbH, Kremsmunster, Austria), centrifuged at 2000 rcf for 10 min, with extracted plasma stored at −80 °C until analysis for HT. Plasma HT was assessed using a liquid–liquid extraction method following acidic hydrolysis, with gas chromatography–mass spectrometry (GC-MS) analysis (Agilent 7820A GC, Santa Clara, CA, USA [45 (link)]).

The samples for VFA were processed following the Ruiz-Moreno et al. (2015) (link) method. The samples were centrifuged at 10,000 × g for 15 min at 4 °C, and the supernatant was collected for analysis. A crotonic and metaphosphoric acid solution was added to the supernatant at a 1:5 ratio and then allowed to freeze overnight. After thawing the samples were centrifuged at 10,000 × g for 15 min at 4 °C. Ethyl acetate was mixed into the supernatant in a 2:1 ratio, vortexed, and allowed to settle. The top layer was transferred to a chromatography vial and analyzed using gas chromatography (Agilent 7820A GC, Agilent Technologies, Palo Alto, CA) with a flame ionization detector and a capillary column (CP-WA × 58 FFAP 25 m 0.53 mm, Varian CP7767, Varian Analytical Instruments, Walnut Creek, CA). The column was maintained at 110 °C with the injector temperature at 200 °C and the detector at 220 °C.

The fatty acids composition was determined according to the standard methodology [18 ] using Agilent 7820A GC (Agilent Technologies, Santa Clara, CA, USA) equipped with a flame ionization detector (FID) and SP-2560 (100 m, 0.25 mm, 0.20 µm) column (Supelco, Bellefonte, PA, USA). The FA methyl esters (FAME) were separated under the following conditions—the initial oven temperature 150 °C and increased to 200 °C at 1.5 °C/min; the injector and detector temperatures were 250 °C; split 1:10; injection volume 0.5 µL and the helium at flow rate 1 mL/min was used as carrier gas. The FAME were identified by comparing with commercially available standards (Grain Fatty Acid Methyl Ester Mix, Supelco, Bellefonte, PA, USA). The results were expressed as % of total FA [19 (link)].

The fatty acid composition was determined according to the AOCS Official Method Ce 1 h-05 [57 ]. The olive oil samples were dissolved in hexane and transesterified with sodium methylate. The fatty acid methyl esters (FAME) composition was analyzed using an Agilent 7820A GC equipped with a flame ionization detector (FID) (Agilent Technologies, Santa Clara, CA, USA) and SLB-IL111 capillary columns (Supelco, Bellefonte, PA, USA) (100 m, 0.25 mm, 0.20 mm). The GC conditions were as follows: the oven temperature from 150 °C to 200 °C with increasing 1.5 °C/min; the temperature of injector and detector 250 °C, the carrier gas was helium at 1 mL/min; the GC operated in split mode 1:10. FAME composition was identified by comparing the retention times of individual substances with a commercially available standard grain fatty acid methyl ester mix (Supelco, Bellefonte, PA, USA). The results were expressed as a percentage of total fatty acids.

Gas pressure was measured at each timepoint using a pressure transducer (JYB-KO-M Pressure Transducer, Kunlun Tech Co Ltd, Beijing, China), for the determination of total gas concentration. Based on the conditions in the laboratory, the following equation was used to convert pressure to volume:
Methane concentration was analyzed by gas chromatography (Agilent 7820A GC; Agilent Technologies, Palo Alto, CA). A flame ionization detector was used with a capillary column (Plot Fused Silica 25 m by 0.32 mm, Coating Molsieve 5A, Varian CP7536; Varian Inc. Lake Forest, CA). Injector, column, and detector temperatures were 80, 160, and 200 °C, respectively. Injector pressure was 20 psi with a total flow of 191.58 mL/min and a split flow of 185.52 mL/min with a 100:1 split ratio. Column pressure was 20 psi with a flow of 1.8552 mL/min. Detector makeup flow was 21.10 mL/min. The carrier gas was N₂, and the run time was 3 min.

Sample processing was done according to the study by Ruiz-Moreno et al. (2015) (link). Briefly, the ruminal fluid used for VFA analysis was thawed at RT and centrifuged at 10,000 × g for 15 min; then the supernatant was mixed with crotonic acid and metaphosphoric acid solution and frozen overnight. The sample was then thawed at RT, centrifuged at 10,000 × g for 15 min and the supernatant was collected. The final supernatant was mixed with ethyl acetate (2:1; ethyl acetate: supernatant), vortexed, and allowed to settle with the top layer being transferred to a chromatography injection vial for analysis. Concentrations of acetate, propionate, butyrate, valerate, iso-butyrate, and iso-valerate in samples were analyzed via gas chromatography (Agilent 7820A GC, Agilent Technologies, Palo Alto, CA, USA) with a flame ionization detector and a capillary column (CP-WAX 58 FFAP, 25 m, 0.53 mm, Varian CP7767, Varian Analytical Instruments, Walnut Creek, CA, USA) where the temperature was maintained at 110 °C, with injector temperature at 200 °C and detector at 220 °C.

The test reaction–liquid phase
benzylation of mesitylene with benzyl alcohol (Figure 10) was carried out in three-neck round-bottom
flasks attached to a reflux condenser with heating in a multiexperiment
workstation StarFish (Radleys Discovery Technologies) under atmospheric
pressure at 80 °C. The reaction was started (0.0 time) by addition
of 0.2 g of benzyl alcohol to the mixture of mesitylene (19.0 g),
50 mg of a catalyst, and dodecane (0.1 g) as an internal standard
that was preheated for 30 min at the reaction temperature. Liquid
samples were withdrawn at regular intervals and analyzed in the gas
chromatograph Agilent 7820A GC with an FID detector using a 30 m packed
DB-5 column. The conversion of alcohol was calculated according to
the formula: where S is the area of respective
peak in the chromatogram, k is the calibration coefficient
(mol), and n₀ is the starting amount of
alcohol (mol). The reaction can proceed by the routes shown in Figure 10.