The swollen co-hydrogels with loaded naproxen were soaked with 7 cm3 of fluids at simulated physiological conditions (pH 2.0 and 7.4 at the temperature of 38 °C). The amount of the released naproxen was monitored for 24 h. Aliquots (100 µL) from the medium with released naproxen were taken in certain intervals of time (after 5 min, 30 min, 60 min, 90 min, 2 h, 3 h, 4 h, 8 h and 24 h), diluted with methanol, filtered through a 0.45 μm cellulose membrane filter and analyzed using HPLC method. The quantification of the amount of the released naproxen as a function of time was performed using the optimized and validated method developed by Somia and colleagues [44 (link)]. HPLC Agilent 1100 Series device with a diode-array detector, DAD 1200 Series (Agilent Technologies, Santa Clara, CA, USA), the Purospher® STAR C18, 25 cm × 4.6 mm, 5 µm (Merck KGaA, Darmstadt, Germany) were applied. The mobile phase was methanol:water, 90:10 (v/v), at pH 2.7 adjusted with phosphoric acid, at the flow rate 1.2 cm3/min with isocratic elution. Agilent ChemStation software was used to process the obtained chromatograms.
Purospher star c18
Manufactured by Merck Group
Sourced in United States, Germany
Purospher® STAR C18 is a high-performance liquid chromatography (HPLC) column designed for the separation and analysis of a wide range of compounds. It features a spherical silica gel as the stationary phase, with a chemically bonded C18 functionality. The column is suitable for reversed-phase HPLC applications.
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3 protocols using purospher star c18
1
Quantifying Naproxen Release from Swollen Co-Hydrogels
2
HPLC Quantification of Tea Catechins
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The sample was extracted by sonication with 100 ml of 50% methanol for 10 min, and 2 ml of the extract was centrifuged at 10,000 rpm (Eppendorf Centrifuge 5402, MI, USA) for another 10 min. After filtrating the supernatant with a 0.22-μm syringe filter (Millipore, Bedford, MA, USA) 20 μl of the filtrate was injected into the High Performance Liquid Chromatography (HPLC) system. HPLC analysis used in this study was performed by a Hitachi 7000 series module equipped with a photodiode array detector and the wavelength was set at 273 nm. Catechin, epicatechin and EGCG were separated individually from the extract using a Merck Purospher STAR C-18 (50*4.6 mm. i.d., 5 μm). The flow rate of the mobile phase was 0.8 ml/min. All samples were analyzed at room temperature (25 ± 1 °C).
3
HPLC Analysis of Water-Soluble and Fat-Soluble Vitamins
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The HPLC system consists of UltiMateDionex 3000 SD pump connected to UltiMateDionex DAD 3000 detector, all from Termo Fischer Scientific® San Jose, CA, USA. The HPLC separations were performed on a reversed-phase Purospher STAR C18 (Merck Millipore, Germany) 5 μm, 25 × 0.46 cm column, conditioned at 25 °C in a column oven. Data were recorded and evaluated by Chromeleon 7.2 software (Thermo Fisher Scientific, San Jose, CA, USA). The applied mobile phase for separation of water-soluble vitamins consists of solvent A: phosphate buffer (pH = 4): acetonitrile (98:2, v/v) and solvent B: methanol:dist. water (50:50, v/v). A gradient elution program was used as follows: 0–3 min eluent B increased to 20% from 15%; 3–30 min eluent B increased to 30% while eluent A decreased linearly; 30–31 min eluent B decreased to 15% and finished with 85% solvent A and 15% solvent B an isocratic elution for 4 min. The total run time was 35 min with 0.8 mL/min flow rate and 20 μL injection volume. For separation of fat-soluble vitamins was used isocratic mode for 20 min with a mobile phase consisting of acetonitrile:methanol (98:2, v/v). For this method, the flow rate was set to 1 mL/min with injection volume of 20 μL.
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