Perkin elmer system

For the quantitative determination of IMQ, an HPLC method was tuned. The analyses were carried out using a Perkin Elmer system (Perkin-Elmer, Shelton, CT, USA) under isocratic conditions. Analyses were performed using an Agilent TC C₁₈ column (250 mm × 4.6 mm × 5 µm; Agilent Technologies, Santa Clara, CA, USA) tempered at room temperature. The mobile phase consisted of acetonitrile:acetate buffer (pH 4.0, 0.05 M):triethylamine (30:69.85:0.15 v/v), the flow rate was 1 mL/min and the detection wavelength was set a 242 nm. Before use, the mobile phase was filtered through a 0.45-μm-pore-size membrane filter and degassed.
The external standard method was used for the calculation of the drug content. For this purpose, about 1 mg of IMQ was weighted and dissolved in methanol in a volumetric flask to get a stock solution. This solution was diluted in the mobile phase, providing a series of calibration solutions, subsequently injected into the HPLC system (Perkin-Elmer, Shelton, CT, USA). The calibration curve was created by plotting the IMQ standard peak area vs. the corresponding drug concentration. A linear calibration curve was obtained in the 0.5–25 μg/mL concentration range with a regression coefficient of 0.999.

Standard stock solutions of all the phenolic acid and flavonoids available were prepared fresh by dissolving the compounds in methanol (10 mg/mL). Working solutions (0.2–1.0 mg/mL) were prepared and standard curves were constructed by plotting concentrations against peak areas. The extracts were prepared as reported previously and filtered through a 0.45 µm non-pyrogenic filter (Minisart, Satorius Stedim Biotech GmbH, Goettingen, Germany) prior to injection [7 (link)].
The HPLC analysis was performed with the Perkin Elmer system (Perkin Elmer, Japan) equipped with gradient model binary pump systems, and a UV/Visible detector. The injection mode was manual, and the degasser (DGU-20A5) system was intact. The column oven was installed and equipped with hypersil GOLD C18 column (250 × 4.6 mm internal diameter, 5 mm particle size) (Thermo Fischer Scientific Inc., Waltham, MA, USA) supported with a guard column and a non-linear gradient consisting of solvent A (acetonitrile: methanol, 70:30) and solvent B (water with 0.5% glacial acetic acid). The quantification was based on an external standard method, whereas the analytes were identified by matching the retention times and spiking the samples with the standard.