The construction and general performance characteristics of a novel potentiometric PVC membrane sensor based on pethidine-phosphomolybdate as electroactive material for the determination of pethidine are described. This sensor exhibits fast, stable and near-Nernstain response 55.24 +/- 0.1, over the concentration range 1.10(-2)-1.10(-5)M for pethidine-phosphomolybdate over pH 2-7. No interferences are caused by many organic, inorganic cations, alkaloids and amino acids. The sensor proved useful for determining pethidine in pure forms, pharmaceutical injections and monitoring the content uniformity assay of ampoules. The designed sensor also show good accuracy for the determination of pethidine in biological fluids.

Abstract:The construction and performance characteristics of phenytoin sodium selective electrodes are detailed. Two types of electrodes:plastic membrane I and coated wire II, were constructed based on the incorporation of phenytoin sodium with tungstosilicic acid. -6 M with a detection limit 1.3×10 -6 M and 2.5×10 -7 M for electrode I and II, respectively. The electrodes gave average selective precision and were usable within the pH range 6-10. Interference studies from common cations, alkaloids, sugars, amino acids and drug excipients are reported. The results obtained by the proposed electrodes were also applied successfully for the determination of the drug in pharmaceutical preparations and biological fluids.

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Objective:Simple, rapid and reproducible reversed-phase high performance liquid chromatography (RP-HPLC) and ultraviolet derivative spectrophotometric (UVDS) methods for the simultaneous determination of daclatasvir (DAC) and sofosbuvir (SOF) in pure and in pharmaceutical dosage forms have been developed and validated.Methods:The chromatographic separation of DAC and SOF was achieved using Agilent Zorbax SB C 18 (4.6 x 250 mm, 5 µm) column at temperature of 40 °C . The mobile phase used was 9 mM dipotassium hydrogen orthophosphate buffer (pH 4±0.1): acetonitrile (60:40, v/v). The flow rate was maintained at 1 mL/min with UV detection at 265 nm.Results:The calculated resolution was 4.56 (> 2), which ensures complete separation. The tailing factor was 1.13 and 1.40 (≤ 2) for DAC and SOF, respectively. Intermediate precision value was ≤ 2% indicate acceptable ruggedness.Conclusion:The two methods were validated according to the International Conference on Harmonization (ICH) guidelines in terms of linearity, precision, accuracy, selectivity, specificity, detection limit, quantification limit, robustness and ruggedness.Egypt. The water for HPLC is doubly distilled and filtered through a 0.45 µm membrane filter. Distilled water was used for all the UVDS method Instrumentation and Analytical ConditionsThe HPLC system used was Agilent Technologies (Santa Clara, CA) 1100 composed of an isocratic pump, manual injector, variable wavelength detector and 2D-value solution ChemStation software. Chromatographic separation was attained on Agilent zorbax SB C 18 (4.6 x 250 mm, 5 µm) column. Elution of samples was achieved using a mobile phase composed of 9 mM dipotassium hydrogen orthophosphate buffer (pH 4±0.1 adjusted with ophosphoric acid): acetonitrile (60:40, v/v). The prepared mobile phase was filtered with 0.45 µm membrane filter and degassed for 30 min in an ultrasonic bath before being used. Flow rate used was 1 mL/min and the injection volume was 20 µL (using a 50 µL Agilent analytical syringe). Column temperature was maintained at 40 °C . The detection wavelength used was 265 nm. Equilibrium, conditioning and pre-washing of the stationary phase was done for 30 -45 min [27].A Shimadzu UV-visible recording spectrophotometer, model UV-2450, with 1 cm quartz cuvettes and connected to an IBM-PC computer loaded with UV Win PC software was used for all the absorbance measurements. Preparation of Standard and Working SolutionsDAC and SOF stock solutions (1 mg/mL) and working solutions (0.2mg/mL) were prepared in the mobile phase for HPLC method. While DAC and SOF stock solutions (1 mg/mL) and working solution (0.1 mg/mL) were prepared in methanol for UVDS method. Procedure for the HPLC methodAccurately measured aliquots of stock solutions (1 mg/mL) equivalent to 20-2000 µg of both DAC and SOF were separately transferred into two series of 10-ml volumetric flasks and completed to volume with the mobile phase. 20 µLof each dilution were injected in triplicate. The chromatograms were recorded using chromatographic conditions ...

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ABSTRACT. The construction and performance characteristics of doxepin hydrochloride selective electrodes were developed. Three types of electrodes: plastic membrane I, coated wire II, and coated graphite rod III were constructed based on the incorporation of doxepin hydrochloride with ammonium reineckate. The influence of membrane composition, kind of plasticizer, pH of the test solution, soaking time, and foreign ions on the electrodes was investigated. The electrodes showed a Nernstain response with a mean slope of 57.41 ± 0.5, 56.22 ± 0.2 and 52.88 ± 0.7 mV at 25 o C for electrode I, II and III respectively, over Doxepin hydrochloride concentration range from 1 × 10 -2 -1 × 10 -6 M, 5 × 10 -2 -1 × 10 -6 M and 1 × 10 -3 -5 × 10 -6 M, and with a detection limit 5.0 × 10 -7 M, 6.3 × 10 -7 M and 2.5 × 10 -6 M for electrode I, II and III respectively. The constructed electrodes gave average selective precise and usable within the pH range 3 -7. Interferences from common cations, alkaloids, sugars, amino acids and drug excipients were reported. The results obtained by the proposed electrodes were also applied successfully to the determination of the drug in pharmaceutical preparations and biological fluids.