Agilent chemstation for lc systems

The concentration of loperamide HCl was determined by HPLC using the 1200 series HPLC system (Agilent Technologies, Santa Clara, CA, USA). The HPLC consisted of a binary pump, autoinjector, column oven, and the ultraviolet–visible detector. The data were integrated using the Agilent ChemStation for LC Systems (version 02/06); Agilent Technologies (Waldbronn, Germany). The separation was performed using a Thermo Scientific Hypersil™ BDS C18 column (150 × 4.6 mm, 5 μm), and the wavelength of detection was 210 nm. The mobile phase consisted of 50% acetonitrile, 5% isopropanol, and a 45% buffer (0.05 M NaH₂PO₄). This was pumped through the column at a flow rate of 1.5 mL/minute. The column was maintained at 25°C. Calibration curves were established by plotting the standard concentrations of loperamide HCl dissolved in PBS pH 6.5 versus the area under the curve. The loperamide HCl release percentage was obtained according to:
where D_t and D₀ indicate the amount of drug released from the liposome suspension at certain intervals and the total amount of drug in the liposome suspension, respectively. At the end of the study, the liposome samples were recovered from the dialysis system and lysed with ethanol for analysis for loperamide HCl content by HPLC.

FK506 in different samples was determined using HPLC. HPLC system (Agilent 1260 series; Agilent Technologies, Santa Clara, CA, USA) consisted of quaternary pump (G1310A), degasser (G1322A), autosampler (G1329), column thermostat (CO-1000), UV detector (G1314A), and data processing software (Agilent ChemStation for LC systems; Agilent Technologies). A C8 column (Grace^®, Grace Davison Discovery Sciences, Deerfield, IL, USA, 250×4.6 mm, 5 μm) was used for FK506 analysis with water:isopropyl alcohol:tetrahydrofuran (5:2:2, v/v/v) as the mobile phase at a flow rate of 0.8 mL/min at 55°C, and the detection wavelength was set at 220 nm.