Fp 2020 plus fluorescence detector

Ochratoxin A analysis was performed using reverse-phase High Performance Liquid Chromatography with fluorometric detection (HPLC-FLD). This consisted of a JASCO AS-2055Plus autosampler, a JASCO LC-Net II/ADC system controller, a JASCO PU-980/LC-980-02 pump, and a JASCO FP-2020Plus fluorescence detector (JASCO Inc., Easton, USA). The samples were separated using a C18 analytical column (250×4.6 nm, 4 μm, Resteck Co., Pinnacle II, Bellefonte, USA) under isocratic conditions at a flow rate of 1 ml min⁻¹ of the mobile phase (water/acetonitrile/acetic acid: 99/99/2). All chemicals used for HPLC analysis were HPLC grade (methanol and acetic acid: Sigma-Aldrich Co., Germany; water and acetonitrile: Carlo Erba Reactifs SDS, Val de Ruill, France). An excitation wavelength of 333 nm and an emission wavelength at 460 nm were used for UV detection. Standard solutions were made from stock ochratoxin A solution (10.06 μg ml⁻¹ in acetonitrile; Biopure, Romer Labs Diagnostics GmbH, Tulln, Austria) in mobile phase and a recovery study took place by spiking known concentration solutions to substrate and following the same extraction procedure as for samples. Run time for samples was 14 min with OTA being detected at about 11 min. The limit of quantification was 2.0 ng OTA g⁻¹ CYA (ppb), while the limit of detection was 1.0 ng OTA g⁻¹ CYA.

The total amino acids in the chia cakes and seeds were determined by using HPLC-DAD-FLD. The total amino acids were obtained via alkaline (KOH 4 M, 4 h, for tryptophan) and acid hydrolysis (HCl 6 M, 24 h, for the other amino acids). Aliquots of neutralized hydrolysates were mixed with the internal standard norvaline (2 mg/mL), according to the method described by Machado et al., in 2020 [44 (link)]. The mixtures were then injected in a HPLC system (Jasco, Tokyo, Japan) that was composed of a LC-NetII/ADC hardware interface; two Jasco PU-980 pumps; an AS-4150 RHPLC autosampler (operating with automatic online derivatization with the reagents OPA/3-MPA and FMOC); a MD-2015 Plus multiwavelength detector (that was used for identification); and a FP-2020 Plus fluorescence detector (that was used for quantification, at λ_exc = 340 nm and λ_em = 450 nm, from 0–26.2 min, for OPA-derivatives; and at λ_exc = 266 nm and λ_em = 305 nm, from 26.2–40 min, for FMOC-derivatives). A ZORBAX Eclipse Plus C18 column (4.6 × 250 mm, 5 μm, Agilent Technologies, Santa Clara, CA, USA) was used for separation in a gradient solvent system.