Binary hplc pump

After imbibed in control, 2.0 g · L⁻¹ of eugenol and eugenol + GA₃ combined solution for 3 h, 9 h, 18 h and 24 h, seed samples were collected and quickly frozen in liquid nitrogen and stored at −80 °C. Approximately, 500 mg of powdered rice seeds were used for ABA measurement with HPLC following the method described by Qin (2013)²⁵ and Tombesi et al.^{26 (link)} with some modification^{25 , 26 (link)}, 20 μL of extraction for each sample was injected into a High Performance Liquid Chromatography system consisting of Binary HPLC Pump (Model 1525, Waters) and Dual λ absorbance detector (Model 2487, Waters). Sample was separated through a C18 reversed-phase chromatographic column (SunFire, 5 μm, 46 × 250 mm, Waters) with flow velocity of 0.8 mL/min. ABA content were calculated according to the standard curve.

Assessment of total polyphenol content was performed according to the modified Singleton method using gallic acid as standard [23 ]. The free amino acid and GABA contents of water extracts of Z. jujuba and D. longan were measured using the AccQ·Tag method (Bae et al., 2023). The high-performance liquid chromatography (HPLC) instrument used was a Waters product consisting of a 1525 pump (Binary HPLC Pump) and a 474 fluorescence detector (Scanning Fluorescence Detector). In addition, an ACCQ-Tag C18 column (3.9 mm × 150 mm I.D., 4 µm) was purchased from Waters and used, and the excitation wavelength of the fluorescence detector was set to 250 nm and the measurement wavelength was set to 390 nm. The flow rate was set at 1 mL per minute and 10 µL was injected. Mobile phase A was used by diluting 100 mL of AccuQTag Eluent A with 1 L of water, and mobile phase B was analyzed in gradient mode using 60% acetonitrile (water: acetonitrile, 40:60, v/v). The quercetin-3-glucuronide (Q3G) content of lettuce (L. sativa) water extract was detected at a wavelength of 350 nm using a YMC-Pack ODS-A column (250 mm × 4.6 mm, 5 μm). The mobile phase consisted of 0.5% formic acid in water (A) and 0.5% formic acid in acetonitrile (B). The gradient of the mobile phase was 80% A for 0 min, 77% A for 5 min, 73% A for 20 min, and 80% A for 25–30 min [24 (link)].

Cyclic voltammograms (CVs) were conducted in a conventional three-electrode electrochemical system by a potentiostat (CHI660D, Chenhua Instrument, China). A saturated calomel electrode (SCE) was used as reference electrode. The anode and cathode of the MCC were used as working and counter electrode, respectively. The linear sweep voltammetry (LSV) of the cathode was measured with potentials ranging from +0.4 V to −0.7 V (versus SCE) by the potentiostat. Sodium acetate concentration was determined by HPLC (Waters1525, Binary HPLC Pump). Samples were filtered (0.2 μm filter) before HPLC analyses using an Agilent Zorbax SB-C18 (250 × 4.6 mm, 5 μm) column, with 0.01 mol L⁻¹ phosphate buffer as the mobile phase (1.0 mL/min). Scanning electron microscopy (SEM) was used to study the morphologies of the cathode algae and the anode bacteria, respectively. Briefly, biofilms formed on the anode and the cathode were fixed directly with glutaraldehyde (2.5%, final) for 5 h. Furthermore, the biofilms were washed and dehydrated by successive 30 min incubations in 25% ethanol, 50% ethanol, 70% ethanol, and 100% ethanol. After dehydration, the biofilms were dried with a critical-point dryer (HCP-2, Hitachi, Japan). The same treatment was conducted for the cathode. The specimens were observed by SEM (JEOL, JSM-6330F, Japan).