Quantitative Analysis of Soluble Sugars

Plant fresh material (0.05 g) was boiled in 2 mL of milliQ water for 10 min before being filtered using 0.22 µm filters. The soluble sugar fraction was analyzed using a Waters 1525 HPLC system coupled to a 2424 evaporative light scattering detector (ELSD), as previously described [52 (link)]. The source parameters of ELSD were the following: gain 75, data rate one point per second, nebulizer heating 60%, drift tube 50 °C, and gas pressure 2.8 Kg/cm². Samples of 20 µL were injected into a Prontosil 120-3-amino column (4.6 × 125 mm; 3 µm particle size) and were maintained at room temperature with a Waters 717 auto-sampler. An isocratic flux (1 mL/min) of 85% acetonitrile (J.T. Baker) was applied in each run for 25 min. Glucose, fructose, and sucrose standards were employed to identify peaks by co-injection. Sugars were quantified with peak integration using the Waters Empower software, and comparisons were made with the glucose, fructose, and sucrose standard calibration curves.