A new ultra-performance liquid chromatography method for the simultaneous determination of valsartan, amlodipine besylate, and hydrochlorothiazide in pharmaceutical formulations has been developed. Chromatographic separation was achieved within 1 min on a sub-2 μm RP18 column using an isocratic mode mobile phase consisting of a mixture of methanol and phosphate buffer (0.05 M, pH 3 ± 0.05) in the ratio 70:30 (v/v). The flow rate was set at 0.3 mL min−1 with a detection wavelength of 239 nm. The method was validated over the concentration ranges from 6.5 to 15.0 μg mL−1 for hydrochlorothiazide, from 5.0 to 12 μg mL−1 for amlodipine besylate and from 76.5 to 178.5 μg mL−1 for valsartan. Calibration plots were linear for valsartan, amlodipine besylate, and hydrochlorothiazide with a correlation coefficient greater than 0.99. Relative variation coefficients for repeatability and reproducibility were less than 3.0%. Recoveries from standard addition essay of individual component in pharmaceutical formulations were varied from 97.0% to 102.0%. The proposed method was successfully applied for the determination of valsartan, amlodipine besylate, and hydrochlorothiazide in pharmaceutical formulations with recoveries with respect to label amount in pharmaceutical formulations that varied from 98.0% to 102.9%. The low flow rate, short analysis time, and simple mobile phase composition make the method cost effective, rapid, nontedious, and successfully employed for simultaneous determination of these drugs in commercial pharmaceutical products.
Authors:B. Habibi, I. Ghorbel-Abid, R. Lahsini, D. Chehimi Ben Hassen and M. Trabelsi-Ayadi
An accurate, sensitive, and reproducible high-performance liquid chromatographic method with diode array detection has been developed for simultaneous determination of erythromycin, clarithromycin, and azithromycin residues in fish muscles. Analysis was carried out using a Shodex Asahipak high-performance liquid chromatography (HPLC) column, monitoring was at 210 nm and a mobile phase consisting of a mixture of acetonitrile and phosphate buffer (pH 11 ± 0.05) in the ratio of 60:40 (v/v). Solid-phase extraction method was used in samples extraction and purification. Recoveries were in the range 72.0–92.2% with relative standard deviation (RSD) from 2.3% to 8.3%. This method was validated for fish muscles in aquaculture following the commission decision 2002/657/EC criteria. It is demonstrated that the new method is robust for detection and quantification of the three macrolides residues. Decision limit (CCα) was from 214 to 228 μg/kg and capacity of detection (CCβ) was from 228 to 256 μg/kg.