Purospher star rp 18e 2 m hibar hr 50 2.1 mm column

For the detection of IBU, a Hitachi Chromaster HPLC-UV system was used consisting of a Hitachi Chromaster pump 5110 with Hitachi Chromaster 5260 autosampler and Purospher^® STAR RP-18e (2 µm) Hibar^® HR 50-2.1 mm column (Merck, Darmstadt, Germany). The column and injector temperature were 50 and 20 °C, respectively. The Mobile phase A was 0.1% formic acid in water and mobile phase B was 0.1% formic acid in acetonitrile. The flow rate was 0.8 mL/min. The injector wash was 50% acetonitrile. Retention time was 4.45 min and run time was 8.0 min. UV detection at the wavelength of 220 nm was used. IBU stock solution was prepared in biorelevant medium at 250 ug/mL and used for the calibration curve by dilution 1:250. Calibration samples were run prior to analysis of the studied samples.

A Hitachi Chromaster HPLC-UV system was optimized for the detection of FFA prior to the analysis. The liquid chromatography system used was a Hitachi Chromaster pump 5110 with a Hitachi Chromaster 5260 autosampler and Purospher^® STAR RP-18e (2 µm) Hibar^® HR 50–2.1 mm column (Merck, Darmstadt, Germany). The column temperature was 50 °C, and injector temperature was 20 °C. The mobile phase A was 0.1% formic acid in water and mobile phase B was 0.1% formic acid in acetonitrile. The flow rate was 0.8 mL/min. The injector wash was 50% acetonitrile. The retention time was 4.45 min, and run time was 8.0 min. UV detection at the wavelength of 280 nm was used. Calibration samples were run prior to the analysis of the study samples by preparing the FFA stock solution in the biorelevant medium at a concentration of 250 μg/mL. The stock solution was used as the calibration standard by a subsequent gradual dilution of 1:250.