Simultaneous Determination of Clidinium Bromide and Chlordiazepoxide in Combined Dosage Forms by High-Performance Liquid Chromatography
A sensitive and precise RP-HPLC method has been developed for the simultaneous estimation of clidinium bromide (CDB) and chlordiazepoxide (CDZ) in pure and pharmaceutical formulations. The separation was achieved on a Nucleodur C8 (250 × 4.6 mm i.d., 5 μm particle size) column at 25°C. CH3CN-MeOH-NH4OAc 0.1M (30 : 40 : 30, v/v/v) was used as the mobile phase at a flow rate of 1.0 mL min−1 and detector wavelength at 218 nm. Almotriptan (ALT) was used as internal standard. The validation of the proposed method was carried out for linearity, accuracy, precision, LOD, LOQ, and robustness. The method showed good linearity in the ranges of 2.5–300.0 and 3.0–500.0 μg mL−1 for CDB and CDZ, respectively. The percentage recovery obtained for CDB and CDZ was 100.40–103.38 and 99.98–105.59%, respectively. LOD and LOQ were 0.088 and 0.294 μg mL−1 for CDB and 0.121 and 0.403 μg mL−1 for CDZ, respectively. The proposed method was successfully applied to the determination of CDB and CDZ in combined dosage forms and the results tallied well with the label claim.
New conventional coated-wire ion-selective electrodes for flow-injection potentiometric determination of chlordiazepoxide.
New chlordiazepoxide hydrochloride (Ch-Cl) ion-selective electrodes (conventional type) based on ion associates, chlordiazepoxidium-phosphomolybdate (I) and chlordiazepoxidium-phosphotungstate (II), were prepared. The electrodes exhibited mean slopes of calibration graphs of 59.4 mV and 60.8 mV per decade of (Ch-Cl) concentration at 25 degrees C for electrodes (I) and (II), respectively. Both electrodes could be used within the concentration range 3.16 x 10(-6)-1 x 10(-2) M (Ch-Cl) within the pH range 2.0-4.5. The standard electrode potentials were determined at different temperatures and used to calculate the isothermal coefficients of the electrodes, which were 0.00139 and 0.00093 V degrees C(-1) for electrodes (I) and (II), respectively. The electrodes showed a very good selectivity for Ch-Cl with respect to the number of inorganic cations, amino acids and sugars. The electrodes were applied to the potentiometric determination of the chlordiazepoxide ion and its pharmaceutical preparation under batch and flow injection conditions. Also, chlordiazepoxide was determined by conductimetric titrations. Graphite, copper and silver coated wires were prepared and characterized as sensors for the drug under investigation.
Plant tissue-based membrane biosensor for L-ascorbic acid
Abstract Coupling of a slice of the mesocarp of squash (Cucurbita pepo) or cucumber (Cucumis sativus) to a Clark-type oxygen electrode allows 0.02–0.57 mmol l−1 l -ascorbic acid to be determined amperometrically. The method is based on monitoring the decrease in the curretn of oxygen at an applied potential of −650 mV vs. Ag/AgCl; oxygen is consumed in the analyte oxidation catalyzed by ascorbate oxidase in the plant tissue. One tissue slice serves for 50–80 measurements at 30°C and pH 6. Spare slices can be stored for at least a year in aqueous 50% glycerol without substantial loss of enzyme activity. The biosensor is highly selective towards ascorbic acid with a response time of 70–90 s, the relative standard deviation being about 3%. Satisfactory results were obtained in the analysis of some fruit juices and vitamin tablets.