7890a gas chromatograph system

A small quantity of C. nudiflora methanol extract was injected into a gas chromatography mass spectrometry (GCMS) system, which consisted of an Agilent 7890A gas chromatograph system coupled with an Agilent 5975C mass spectrometry detector. A capillary column, HP-5MS (30 m × 0.25 mm) of 0.25 μm film thickness of coated material, was used. The injector temperature was set at 250 °C whereas the temperature settings were as follows: start at 40 °C and hold for 3 min; from 40 to 200 °C with 3 °C/min and then hold for 3 min. A post-run of 5 min at 200 °C was sufficient for the next injection. A gas chromatography was performed in splitless mode. Helium gas was used as a carrier gas and maintained at a 1.0 ml/min constant flow rate. Identification of various compounds was carried out by referring to the NIST library, and the chemical makeup was computed with reference to the abundance of the compounds in a chromatogram. Each analysis was carried out in triplicate, together with a blank solvent.

LADH kinetics measurements were carried out in a quartz fixed-bed reactor with 3/8-inch ID. Catalysts around 0.02–0.15 g were diluted using pure SiO₂ to achieve a total weight of 1.00 g for testing the performance. Reaction temperature was measured using a thermocouple inserted in a stainless-steel thermocouple well locating at the bottom center of the catalyst bed. Agilent 7890A gas chromatograph system quipped with a flame ionization detector (FID) was employed for analyzing the products. Prior to each measurement, the fresh catalysts were reduced by 5% H₂/N₂ (50 cm³ min⁻¹) for 30 min at 550 °C with the temperature ramping rate of 15 °C min⁻¹. Propane dehydrogenation was tested under a reaction atmosphere of 2.5% C₃H₈, 2.5% H₂ balanced with N₂. The total flow rate of the reactant mixture was 200 cm³ min⁻¹. After 2 min on-stream, the catalyst selectivity was compared below 20% conversion at 550 °C and turnover rates (TORs, per surface Pt site) were measured under differential condition at conversion below 5%. For iso-butane dehydrogenation, a reaction atmosphere of 2.5% C₃H₈, 2.5% H₂ balanced in N₂ with a total flow rate of 100 cm³ min⁻¹ was used. Catalyst performance was measured at 450 °C.

Fatty acids were determined after the extraction and transesterification procedures described by Pojić et al. [16 (link)]. Briefly, lipids were extracted with chloroform/methanol mixture (2 : 1 v/v), and the extracts obtained were dried by vacuum evaporation at 40°C. Further, methyl esters were prepared from the extracted lipids by transesterification with 14% boron trifluoride in methanol. The fatty acid profile was analysed with an Agilent 7890A gas chromatograph system (Santa Clara CA, United States) with a flame ionization detector equipped with a fused silica capillary column (DB-WAX 30 m, 0.25 mm, 0.50 µm). The carrier gas was helium with a flow rate of 1.26 ml min⁻¹. The fatty acid peaks were identified by comparing relative retention times of FAME from the sample with retention times of standards from Sigma-Aldrich Chemical Co. 37 component FAME mix (St Louis, MO, USA) and with data from an internal data library. The results were expressed as a weight percentage of crude fat.