1290 infinity elsd

UHPLC (Agilent Technologies, Santa Clara, CA, USA) was used to analyze the liquid fraction that resulted after pretreatment for monosaccharides (glucose, mannose, galactose, xylose, and arabinose), HMF, and furfural. The content of mono-sugars was analyzed by UHPLC (1260 Infinity II), which contains a quaternary pump (Agilent Technologies, G7111B, 1260 Infinity II, Santa Clara, CA, USA), an Agilent Autosampler with an injection valve fitted with a 20 µL sample loop. The separation was performed on a 5 µm Polaris NH₂ 250 × 4.6 mm (Agilent Technologies, Santa Clara, CA, USA). The column temperature (Agilent Technologies 1290 Infinity II Multicolumn Thermostat, Santa Clara, CA, USA) was kept constant at 30 °C, and the mobile phase flow rate was 0.6 mL.min⁻¹. The Evaporative Light Scattering Detector (ELSD) (Agilent Technologies, 1290 Infinity ELSD, Santa Clara, CA, USA) has the following characteristics: nebulization temperature of 70 °C, evaporation temperature of 90 °C, and gas flow of 1.2 SLM. The eluent used was acetonitrile: water (75:25) with a flow rate of 0.6 mL min⁻¹ and an injection volume of 20 µL. All the samples were filtered through a 0.45 µM PTFE filter for LC analysis.
The content of furfural and HMF was analyzed according to our recent methods published [40 (link),41 ].

The beetroot samples were prepared according to the method described in Kojić et al. [33 (link)] to determine betaine content. In brief, the ground sample (0.5 g) was suspended in 25 mL of methanol and vortexed for 10 min. Following a 30 min ultrasonic extraction in an ultrasound bath at room temperature, the sample underwent vigorous shaking and was then centrifuged for 10 min at 5000 rpm (Eppendorf Centrifuge 5804R, Eppendorf, Wien, Austria). The resulting upper methanol layer was evaporated to dryness. Then, the residue was reconstituted in 2 mL of water and filtered through a membrane filter based on regenerated cellulose (pore size 0.22 mm, diameter 25 mm) to obtain the sample extract. An HPLC system (Agilent Technologies Inc., Santa Clara, CA, USA) fitted with an ELSD detector (1290 Infinity ELSD, Agilent Technologies Inc., Santa Clara, CA, USA) and a Kinetex HILIC (Phenomenex, Aschaffenburg, Germany) column (2.6 µm, 100 × 2.1 mm) was used to quantify the betaine content. The mobile phase for the analysis was an 80:20 combination of acetonitrile and 10 mM acetate buffer (pH 3.7), with a flow rate of 0.5 mL/min. Ten minutes was the whole run time, and there was a 5 µL injection volume.