A selective and sensitive stability-indicating LC-MS/MS method, operated in ESI and quadrupole linear ion trap (QTRAP) modes, has been developed for the identification and structural characterization of stressed degradation products of indapamide.
A spectrofluorimetric method was developed for the determination of albendazole (ALB) through charge transfer (CT) complex formation with 7,7,8,8-tetracyanoquinodimethane (TCNQ). TCNQ was found to react with ALB to produce a stable complex, and the fluorescence intensity of the complex was enhanced to 25 times higher than that of the studied drug itself. Different experimental parameters that affect the fluorescence intensity were carefully studied, at optimum reaction conditions, the drug-TCNQ complex showed an excitation maxima at 295 nm and an emission maxima at 476 nm. A rectilinear calibration graph was obtained in the concentration range of 100-800 ng ml À1 . Thermodynamics parameters were calculated as: association constant KC of 7.28 Â 10 3 mol À1 dm 3 and a Gibbs free energy DG of À4.66 kJ mol À1 . The developed method was applied successfully to the determination of the studied drug in its pharmaceutical dosage form with good precision and accuracy compared to official and reported methods as revealed by tand F-tests.
Objective: Development and validation of four simple, accurate, selective and sensitive UV spectrophotometric methods for the determination of rafoxanide in the presence of its alkali-induced degradation product without preliminary separation. Methods: (A) Dual wavelength method, where the difference in absorbance were calculated at 242 and 281 nm. (B) Area under the curve method, where area under the peak were measured at wavelength ranges (225-235 nm) and (275-295 nm). (C) Bivariate method, where the absorbance values were measured at selected wavelengths 250 and 280 nm. (D) First derivative method, where The amplitudes were measured at 253 nm. Results: Good linearity was found in the concentration range of 2.5-25 μg/mL for all the methods. The specificity of the methods were assessed by analysing synthetic mixtures containing the drug and its degradation product. Methods are validated as per ICH guidelines and accuracy, precision, repeatability and robustness are found to be within the acceptable limit. Conclusion: The proposed methods have been found to be accurate, precise and can be used for determination of the drug in pure form and pharmaceutical formulations as well as in the presence of its degradation product without any preliminary separation steps.
A specific and precise High-performance liquid chromatography (HPLC) method with diode array detection (DAD) has been sophisticated for tetramethrin determination in environmental water samples. Water samples were collected from two governorates in Upper Egypt: Assiut and Qena. Extraction of tetramethrin from water samples was carried out using liquid-liquid extraction method before the injection of analyte into HPLC-DAD system. The best separation method has been achieved on the Supelcosil TM LC-18-DB column (4.6* 250mm), particle size 5μm, with mobile phase methanol: water (78:22,v/v) at temperature of 30O°C and at a flow rate of 0.8mL/min. The detection wavelength of the detector was set at 220nm. Calibration curves obtained over the concentration range of 10-100µg mL -1 were linear. The accuracy ranged from 99.44% to 102.07%. The suggested study showed that most of samples do not contain tetramethrin residues, while few samples contain tetramethrin residues.
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