Kromasil 100a 5u c18 4.6 mm

Ascorbic acid was extracted from 1 g of tomato peel dispersed in 2 mL of distilled water followed by homogenization with Ultra-Turrax (IKA^®) and filtration through a 0.45 µm membrane filter [66 (link)]. For the HPLC method, an RP-C18 column (SUPELCO Kromasil 100A-5u-C18 4.6 mm × 250 mm) was used. The mobile phase consisted of 0.01 mol/L KH₂PO₄ buffer solution (pH = 2.6 with o-phosphoric acid), with a flow rate of 0.5 mL/min and a detection absorbance set at 250 nm. For quantification, a standard calibration curve consisting of five points at the increasing concentrations of 6.25, 12.5, 25, 50 and 100 µg/mL of ascorbic acid standard (Sigma Chemical, St. Louis, MI, USA) was used.

Extraction of ascorbic acid was carried out using 1 g of both tomato peel and pulp (taken from the pull described previously in Section 2.4) in 2 mL of distilled water; samples were homogenized with Ultra-Turrax (IKA^®), then filtered through a 0.45-µm membrane filter [41 (link)]. For HPLC analysis, an RP-C18 column (SUPELCO Kromasil 100A-5u-C18 4.6 mm × 250 mm) was used. The mobile phase consisted of 0.01 mol/l KH2PO4 buffer solution (pH = 2.6 with o-phosphoric acid), with a flow rate of 0.5 mL/min and an absorbance set at 250 nm. The quantification was carried out using a standard calibration curve consisting of five points at increasing concentrations (6.25, 12.5, 25, 50, and 100 µg/mL) of ascorbic acid standard (Sigma Chemical, St. Louis, MO, USA). The experiment was conducted in three technical replicates for each sample. Finally, the mean and standard deviation were calculated. To verify the significance of the data obtained, t-tests (* p ≤ 0.05, ** p ≤ 0.01) were carried out.