A simple, rapid, sensitive, and economic reversed-phase High Pressure Liquid Chromatography method was developed for the simultaneous evaluation of five binary mixtures in their pharmaceutical preparations. The investigated mixtures were Ibuprofen(IP)-paracetamol(PC), Ibuprofen(IP)-Chlorzoxazone(CZ), Ibuprofen(IP)- Methocarbamol(MC), Ketoprofen(KP)-Chlorzoxazone(CZ), and Diclofenac sodium(DS)-Lidocaine hydrochloride(LC). The chromatographic separation was performed using isochratic mode at a flow rate 1 mL/ min, ODS C₁₈ column, and UV detection at 254 nm. The mobile phase consisted of acetonitrile:phosphate buffer, pH 5 (60:40). The parameters affecting separation of the investigated drugs were studied. Under the optimum assay conditions, the method gave linear calibration curves with good correlation coefficients. The limits of detection (LOD) and limits of quantitation (LOQ) ranged from 0.34–5.33 µg/mL and 1.03–16 µg/mL, respectively, indicating high sensitivity of the method. The assay of the investigated binary mixtures is completed in less than 5 min. The proposed method was successfully applied to the simultaneous analysis of the drugs in their pharmaceutical binary mixtures in dosage forms with good recoveries and no significant differences between proposed and reported method. This method can be routinely applied to the quality control of the investigated binary mixtures in their pharmaceutical formulations.

A simple and selective micellar electrokinetic chromatographic (MEKC) method has been developed for the analysis of five pharmaceutical binary mixtures containing three non-steroidal anti-inflammatory drugs (NSAIDs). The investigated mixtures were Ibuprofen (IP)-Paracetamol (PC), Ibuprofen (IP)-Chlorzoxazone (CZ), Ibuprofen (IP)-Methocarbamol (MC), Ketoprofen (KP)-Chlorzoxazone (CZ) and Diclofenac sodium (DS)-Lidocaine hydrochloride (LC). The separation was run for all mixtures using borate buffer (20 mM, pH 9) containing 15% (v/v) methanol and 100 mM sodium dodecyl sulphate (SDS) at 15 kV and the components were detected at 214 nm. Different factors affecting the electrophoretic mobility of the seven investigated drugs were studied and optimized. The method was validated according to international conference of harmonization (ICH) guidelines and United States pharmacopoeia (USP). The method was applied to the analysis of five pharmaceutical binary mixtures in their dosage forms. The results were compared with other reported high performance liquid chromatographic methods and no significant differences were observed.

Geometry optimization of gemcitabine was carried out by DFT with B3LYP/6-311++G(d,p) level in the gas phase. Chemical activity (electronegativity, electrophilicity, hardness, chemical softness and chemical potential) was predicted with the help of HOMO-LUMO energy values. Experimental FT-IR was recorded and computed values are also analyzed using the same level of DFT. A complete vibrational spectrum was made to analyze the potential energy distribution (PED). Stability of the molecule arising from the hyper-conjugative interaction was analyzed by the natural bond orbital (NBO). The molecular electrostatic potential map was used to detect the possible electrophilic and nucleophilic sites in the molecule. Nonisothermal decomposition of gemcitabine was carried out in an air atmosphere. The two decomposition steps of the molecule were analyzed kinetically by linear and nonlinear methods for elucidation of the kinetic triplet (E_a , ln A and f(α)) of the decomposition processes. Powder X-ray diffraction indicated that gemcitabine crystallizes in the monoclinic system (SG P2/m). Molecular docking studies were also described.