Determination of diclofenac sodium in rat plasma by HPLC-UV with cloud-point extraction

Objectives:To develop a method based on cloud-point extraction (CPE) for determination diclofenac sodium in rat plasma by high performance liquid chromatography separation and ultraviolet detection (HPLC-UV).Methods:The non-ionic surfactant Triton X-114 was chosen as the extract solvent.The DiamonsilTMC18was used as analytical column with a mobile phase consisting of sodium acetic solution(0.02 mol·L-1)-acetonitrile(35∶65 v/v).Variable parameters affecting the CPE efficiency were evaluated and optimized with detection wavelength at 225 nm.Results:Under the optimum conditions,the method was shown to be reproducible and reliable with intraday precision not more than 7.7%,interday precision not more than 11.4%,and accuracy within ±5.8% and mean extraction recovery more than 83.4%,which were all calculated using a range of spiked samples at three concentrations of 0.5,25 and 160 μg·mL-1 for diclofenac sodium in plasma.The linear range was from 0.25 to 200 μg·mL-1.Conclusion:After strict validation,the method were successfully applied to the pharmacokinetic study of diclofenac sodium in rats after i.v.and i.g.administration,respectively.