As 1555 automatic injector

Individual organic acids were determined by HPLC, based on procedures optimized by [33 ] and applied to different types of plant samples by [34 (link),35 (link),36 (link)]. Extraction was performed with 0.5 g of dried sample in 25 mL of 4.5% m-phosphoric acid and analyzed using an HPLC-UV methodology.
The HPLC equipment was a liquid chromatographer equipped with an isocratic pump (model PU-II, Micron Analítica, Madrid, Spain), an AS-1555 automatic injector (Jasco, Tokyo, Japan), a Sphereclone ODS (2) 250 × 4.60, 5 mm Phenomenex column (Torrance, CA, USA), a UV detector (Thermo Separation Specta Series UV100, San Jose, CA, USA) working at 215 nm. The mobile phase was 1.8 mmol/L H₂SO₄ (pH 2.6) at 0.4 mL/min flow rate. Data were analyzed using Chromonec XP software (Micronec, Madrid, Spain). Identification was performed comparing retention times with those obtained from commercial pure standards of oxalic, malic, citric, and succinic acids. Quantification was based on the UV signal response, and the resultant peak areas in the chromatograms were plotted against concentrations obtained from standards (Figure 1). Organic acids contents in S. patula samples were expressed as mg/100 g of fresh plant material.

Organic acids were determined based on protocols described by Sánchez-Mata et al. [46 (link)]. Extraction was performed with 0.5 g of sample in 25 mL of 3% m-phosphoric acid and analyzed using an HPLC-UV methodology. The HPLC equipment used was a liquid chromatograph (Micron Analítica, Madrid, Spain) equipped with a Sphereclone ODS (2) 250 * 4.60 mm, 5 µm Phenomenex column, isocratic pump (model PU-II), an AS-1555 automatic injector (Jasco, Tokyo, Japan), and a UV-visible detector (Thermo Separation Spectra Series UV100, Waltham, MO, USA), 215 nm for organic acids. The mobile phase was 1.8 mM H₂SO₄ (pH = 2.6), with a flow rate of 0.4 mL/min for organic acids, and injection volume was 100 µL for samples and serial volumes for the standard curve (20, 30, 40, 50, 60, 70, 80, 90, and 100 µL). The compounds were identified by chromatographic comparisons with authentic standards (quinic (0.152 mg/mL), ascorbic (0.155 mg/mL), malic (0.403 mg/mL), fumaric (0.254 mg/mL) and citric acids (0.307 mg/mL), all from Sigma, St. Louis, MO, USA), using linear calibration curves of all compounds for quantification purposes. All data were analyzed using Biocrom 2000 3.0 software (Biocrom, Madrid, Spain).

Vitamin C (Ascorbic and dehydroascorbic acid), as well as individual organic acids (oxalic, glutamic, malic, and citric), was determined based on protocols described by Sánchez-Mata et al. [42 (link)], using an HPLC-UV methodology after samples extraction with 4.5% m-phosphoric acid. The HPLC equipment used was a liquid chromatograph (Micron Analítica, Madrid, Spain) equipped with a Sphereclone ODS (2) 250 × 4.60, 5 μm Phenomenex column, isocratic pump (model PU-II), an AS-1555 automatic injector (Jasco, Japan), and a UV-visible detector (Thermo Separation Specta Series UV100), working at 245 nm for AA or 215 nm for organic acids. The mobile phase was 1.8 mM H₂SO₄ (pH = 2.6), with a flow rate of 0.9 mL/min for AA or 0.4 mL/min for organic acids. The compounds were identified by chromatographic comparisons with authentic standards (AA, oxalic, malic, and citric acids, all from Sigma, St. Louis, MO, USA), and glutamic acid (Merck, Germany) using linear calibration curves of all compounds for quantification purposes. All data were analyzed using Biocrom 2000 3.0 software (Biocrom, Madrid, Spain). Vitamin C and organic acids content were expressed in mg/100 g of fresh weight (fw).