As a part of preliminary studies, the possibility quantitative oxidation aldehydes to carboxylic acids and their determination by isocratic ion chromatography with conductometric detection has been tested. A methodology for simultaneous separation inorganic anions (F-, Cl-, NO2-, Br-, NO3-, PO43-, SO42-) (formate, acetate oxalate) using conductivity have developed validated. Six anion-exchange ...

Methods: A simple, isocratic reverse-phase high performance liquid chromatographic (RP-HPLC) method has been developed for simultaneous estimation of methotrexate, dexamethasone and indomethacin using ibuprofen (IBP) as internal standard with photodiode array detection at 254 nm. The process was carried out on C18 column (5 μm, 250 mm X 4.6 mm) using methanol: orthophosphoric acid (1.67 % v/v) ...

Two unknown impurities were detected in verapamil hydrochloride bulk drug using isocratic reversed-phase high performance liquid chromatography (HPLC). These impurities were isolated by preparative HPLC. Spectral data for the isolated impurities were collected. Based on the spectral data derived from two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy and mass spectrometry (MS), im...

column (250×4.6 mm, 5 μm) in isocratic mode, the mobile phase consisted of methanol, acetonitrile and 0.05 M phosphate buffer (adjusted to pH 4.5 with ortho-phosphoric acid) at a ratio of 60:20:20 v/v/v, and a flow rate of 1.0 mL/min. The eluents were monitored at 254 nm. The retention time of lamivudine and efavirenz were found to be 2.50 min and 4.25 min, respectively. The linear ranges were ...

The ability of LC-NMR to detect simultaneously free and conjugated phytosterols in natural extracts was tested. The advantages and disadvantages of a gradient HPLC-NMR method were compared to the fast composition screening using SEC-NMR method. Fractions of free and conjugated phytosterols were isolated and analyzed by isocratic HPLC-NMR methods. The results of qualitative and quantitative anal...