Finnigan surveyor plus

All the liquid samples were collected by a sampling valve at the bottom of the bioreactor and used to analyze biomass and product concentration. The samples were analyzed with a UV–Vis spectrophotometer (Genesys 10S UV–Vis, Thermo Scientific, Neuss, Germany) for optical density (OD_600nm) measurements, and a correlation factor was used to obtain CDW concentrations. Maximum specific growth rates were estimated by applying a non-linear regression to the experimentally obtained data for CDW concentrations. High-performance liquid chromatography (HPLC; Finnigan Surveyor Plus, Thermo Scientific, Waltham, MA, United States) was used to analyze the product and metabolite concentrations in the liquid phase (formic acid, acetic acid, butyric acid, caproic acid, ethanol, and 1-butanol). The samples with 1-hexanol were extracted and concentrated with ethyl acetate in a ratio of 3:1 (sample to solvent) before the measurement. The HPLC instrument used a refractive index detector to detect the products and a cation exchange separation column HPX-87H (Bio-Rad, Munich, Germany) at a column temperature of 60°C. The elution was carried out isocratically with 5 mM H₂SO₄ at a flow rate of 0.6 mL min⁻¹.

The phenolic profile of Moringa oleifera leaves extracted with deep eutectic solvent (GLY and LA) was studied using the HPLC system (Thermo Electron Corporation, Waltham, MA, USA) coupled with an ion-trap mass spectrometer and diode array detector (DAD), equipped with a low-pressure quaternary pump with an autosampler and a diode array detector (Finnigan Surveyor Plus, Thermo Fisher Scientific, Waltham, MA USA). The qualitative analysis of the samples was carried out as described previously.

After 12 weeks, 3 birds from each replicate were chosen and placed in a metabolic cage with a feces sample collection tray. For three days, fecal samples were collected at 12 h intervals and stored in sealed bags at −20 °C. Feed, feathers, and other extraneous components in the feces samples were meticulously removed during collection to guarantee that the fecal sample was not contaminated. Fecal samples were thawed and dried at 70 °C for 72 h before being pulverized to a fine powder that could pass through a 0.05 mm mesh. The feed intake and feces weight (dry matter basis) from each metabolic cage were computed for apparent fecal amino acid digestibility. Amino acid analysis was performed on the fecal and feed samples using HPLC and adopting the established method by [30 ]. The HPLC system Finnigan Surveyor Plus and HyperSil BDS C18 column, size 250 × 4.6 mm, 5μm (Thermo-Electron Corporation, Waltham, MA, USA) was used. Apparent fecal amino acid digestibility % was calculated as: 1 − (amino acid concentration in feces ÷ amino acid concentration in feed) ×100.