Hplc model 1260 infinity

The CAP and DHCA contents were analyzed as previously described [20 (link)] with minor modifications. Briefly, 15 mL methanol was added to a vial containing 2.5 g of homogenized kimchi and two or three glass beads. The mixture was placed on a heating block at 90 °C for 1 h and then cooled. The cooled extract was passed through a filter paper (8 μm, Whatman No. 2, Kent, UK), and methanol was added to the filtered solution to bring the volume to 25 mL; the solution was filtered again through a 0.2-μm syringe filter (Millipore, Billerica, MA, USA). The analysis was conducted using HPLC Model 1260 Infinity; Agilent Technologies, Santa Clara, CA, USA) coupled with a fluorescence detector (Agilent Technologies, Santa Clara, CA, USA). Excitation and emission wavelengths were set to 208 and 325 nm, respectively. To separate CAP and DHCA, a Lachrom Ultra C18 column (2 × 50 mm, 2 μL; Hitachi, Tokyo, Japan) was used with 0.1% acetic acid and acetonitrile (6:4, v/v) as mobile phase at a flow rate of 0.6 mL/min with an injection volume of 2 μL.

The furfural and hydroxymethylfurfural (HMF) contents were determined in a HPLC (Agilent HPLC, model 1260 Infinity, Santa Clara, CA, USA), equipped with a quaternary pump (G1311C), a Rheodyne injection valve with a 20 μL loop, an oven (G1316A), and a diode array detector (DAD) (G1328C). For all the chromatographic analyses, samples and solvents were filtered using 0.22 and 0.45 μm membranes, respectively (Millipore, Billerica, MA, USA). The compounds were separated in a C₁₈ column (Nova-Pak Waters, Milford, MA, USA) with an isocratic mobile phase of acetonitrile/water (1:8, v/v) with 1% acetic acid, at 30 °C, flow rate at 0.8 mL/min, and the chromatograms were monitored at 280 nm for 20 min [3 (link)]. The furfural and HMF contents were determined, in triplicate, by analytical curves (0.001 to 0.1 g/L, R² > 0.99), and the results are expressed in g/L.