The performance of a molecularly imprinted polymer (MIP) as selective packing material for solid-phase extraction (SPE) of residual glibenclamide in an industrial process was investigated. MIP was prepared using 4-vinylpyridine as monomer, ethylenedimethacrylate as cross linker, 2,2’-azobis-2-methylpropionitrile as initiator and dimethyl formamide as porogen. Use of acetonitrile as a rebinding solvent allows good recognition of the glibenclamide template. It was found that this polymer can be used for determination of trace levels of glibenclamide with a recovery percentage that could reach 87.1 %. Furthermore, the synthesized MIP showed higher selectivity towards glibenclamide than other compounds such as glimepiride and metformine. The synthesized MIP enabled direct determination of the target contaminant after an enrichment step that allowed quantification of glibenclamide at a concentration as low as 0.016 mg L-1. Combination of high performance liquid chromatography with MIP-SPE could be successfully used for quality control of pharmaceuticals during the cleaning process in the production of dry drug forms.
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.
Summary.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.
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