Sensitive Spectrophotometric Methods for the Determination of Gatifloxacin in Pharmaceuticals Using Bromate-Bromide, Methylene Blue and Rhodamine-B as Reagents

A simple spectrophotometric method is proposed for the determination of zidovudine(ZDV) in bulk drug and in pharmaceutical preparations. The method is based on the oxidation of ZDV by a known excess of oxidant N-bromosuccinimide (NBS), in buffer medium of pH 1.5, followed by the estimation of unreacted amount of oxidant with metol and sulphanilic acid. The reacted oxidant corresponds to the amount ZDV. The purple-red reaction product absorbs maximally at 530 nm and Beer’s law is obeyed over a range 5 to 75 μg mL-1. The apparent molar absorptivity is calculated to be 5.1×103 L mol-1cm-1, and the corresponding Sandell sensitivity value is 0.052 μg cm-2. The limit of detection and quantification are found to be 0.90 and 2.72, respectively. Intra-day and inter-day precision and accuracy of the developed methods were evaluated as per the current ICH guidelines. The method was successfully applied to the assay of ZDV in tablet/capsule preparations and the results were statistically compared with those of the reference method by applying the Student’s t-test and F-test. No interference was observed from the common tablet/capsule excipients. The accuracy of the method was further ascertained by performing recovery studies via standard-addition method

Sensitive and selective spectrophotometric determination of pantoprazole sodium in pharmaceuticals using permanganate

A simple visible spectrophotometric method is described for the determination of pantoprazole sodium sesquihydrate (PSS). The method is based on the formation of a brown colored product on treating PSS with permanganate in neutral medium, the absorbance being measured at 350 nm. The experimental conditions for the assay were optimized. The absorbance is found to increase linearly with the concentration of PSS and the calibration graph is linear in the range of 2.5-40.0 μg ml-1 with a linear regression coefficient of 0.998. The calculated molar absorptivity value is 1.27x104 l mol-1 cm-1 and the corresponding Sandel sensitivity is 0.0341 µg cm-2. The limits of detection (LOD) and quantification (LOQ) are calculated to be 0.49 and 1.47 µg ml-1, respectively. Intra-day and inter-day accuracy expressed as relative error were better than 2.0% and the corresponding precision (RSD) was less than 2.5 %. The developed and validated method was applied to the determination of the active ingredient in a tablet dosage form and the results obtained agreed well with those of the reference method. The accuracy and reliability of the method were ascertained by performing recovery experiments via standard-addition procedure

Simple High-performance Liquid Chromatographic Method for the Determination of Acyclovir in Pharmaceuticals

An assay method for the determination of acyclovir from pharmaceutical preparations has been developed for assessment of product quality utilising high-performance liquid chromatography. The chromatographic conditions comprised a reversed-phase C18 column (250×4.6 mm i.d.) with a mobile phase of acetonitrile-20 mmol l−1 aqueous ammonium acetate buffer of pH 4.5 (40:60). The flow rate was 0.8 ml min−1 and UV detection was used at 250 nm. Calibration graph was linear in the range 1.98–59.4 μg ml−1. The method has been validated according to current guidelines including assay of pharmacopoeial standard tablets. Recoveries ranged from 96.64 to 99.53%. The exipients present in the tablets did not interfere with the method

SIMPLE AND SENSITIVE SPECTROPHOTO¬METRIC ASSAY OF OFLOXACIN IN PHARMACEUTICALS BASED ON ION-PAIR REACTION

Two simple, sensitive, economical and extraction-free spectrophotometric methods have been developed for the determination of ofloxacin (OFX) in pure form and in tablets. The methods are based on the interaction of OFX with two sulphonphthalein dyes, namely, bromothymol blue (method A) and bromophenol blue (method B) in dichloromethane medium to form stable, yellow-colored ion–pair complexes peaking at 410 nm. Under the optimum conditions, OFX could be assayed in the concentration ranges 1.25-20 and 1.0-16 µg mL-1 OFX by methods A and B, respectively, with correlation coefficient of 0.999 in both methods. The apparent molar absorptivity values are calculated to be 1.74104 and 2.18104, L moL-1 cm-1, for method A and B, respectively, with corres¬pond¬ing Sandell sensitivity values of 0.021 and 0.017 µg cm-2. The limits of detec¬tion (LOD) and quantification (LOQ) are also reported. The stoichiometry of the reaction was found to be 1:1 in both cases and the conditional stability cons¬tants (Kf) of the complexes have also been reported. The intra-day and inter-day variation was assessed. The methods were applied to determine OFX from marked tablet formulations. Statistical analysis proved that the proposed methods were both accurate and precise

Synthesis and Characterization of a Novel Class of Lewis Acid Doped Tetraaniline

Boron trifluoride (BF3) doped tetraaniline with novel structure were successfully synthesized via two step method. In the first step, emeraldine base form tetraaniline was synthesized via oxidative chemical polymerization of N-phenyl-1, 4-phenylenediamine using ammonium persulphate as oxidant. In the second step involves control BF3 doping of tetraaniline using boron trifluoride etherate. As synthesized BF3 doped tetraaniline have been well characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction patterns (XRD), and scanning electron microscopy (SEM) and thermogravimetry. Thermogravimetry studies revealed that the BF3 doping improved the thermal stability of tetraaniline

Utilization of bromination reactions for the determination of carbamazepine using bromate-bromide mixture as a green brominating agent

One titrimetric and two spectrophotometric procedures have been developed for the assay of carbamazepine (CBZ) in bulk drug, formulations and spiked human urine. The methods are based on the bromination of CBZ by the bromine generated in situ by the action of the acid on the bromate-bromide mixture. The twin advantages of avoiding liquid bromine and analysis in a cost-effective manner are realized. In titrimetry, the drug was treated with a known excess of bromate-bromide mixture in hydrochloric acid medium followed by the determination of unreacted bromine iodometrically. Spectrophotometry involves the addition of a measured excess of bromate-bromide reagent in acid medium to CBZ, and after the reaction is ensured to be complete, the residual bromine was determined by reacting with a fixed amount of either methyl orange and measuring the absorbance at 510nm (method A) or indigo carmine and measuring the absorbance at 610nm (method B). Titrimetric procedure is applicable over the range of 1.00-7.50mg CBZ, and the calculations are based on a 1:1 reaction stoichiometry (CBZ:KBrO3). In spectrophotometric methods, Beer's law is valid within concentration ranges of 0.25-1.50 and 0.50-6.00μgml-1 CBZ for methods A and B, respectively. The proposed methods were successfully applied to the determination of CBZ in tablets and syrup, in addition to spiked human urine by the spectrophotometric methods, with mean recoveries of 95.50-104.0% and the results were statistically compared with those of an official method by applying Student's t-test and F-test

NON-AQUEOUS TITRIMETRIC ASSAY OF GABAPENTIN IN CAPSULES USING PERCHLORIC ACID AS TITRANT Non-aqueous titrimetric assay of gabapentin in capsules using perchloric acid as titrant

Two simple, rapid, accurate and inexpensive methods using visual and potentiometric titrimetric techniques are described for the determination of gabapentin (GBP) in bulk drug as well as in capsules. The methods are based on the neutralization reaction of the primary amino group of GBP with acetous perchloric acid as titrant in anhydrous acetic acid medium. The end point was detected either visually using crystal violet as indicator or potentiometrically using a modified glass electrode SCE electrode system. Both methods are applicable over the range 1.0-16.0 mg of GBP and the titration reaction follows a 1:1 stoichiometry. The methods were successfully applied to the determination of GBP in capsules. The validity of the proposed methods was further ascertained by parallel determination by a reference method and by recovery studies via standard-addition technique

Simple Spectrophotometric Methods for the Determination of Zidovudine in Pharmaceuticals Using Chloramine-T, Methylene Blue and Rhodamine-B as Reagents

Two new spectrophotometric methods are proposed for the determination of zidovudine(ZDV) in pharmaceuticals. The methods use chloramine-T (CAT) and two dyes, methylene blue and rhodamine-B, as reagents and are based on adding of a known excess of CAT to ZDV in hydrochloric acid medium followed by determination of residual oxidant by reacting with a fixed amount of either methylene blue and measuring the absorbance at 665 nm (Method A) or rhodamine B and measuring the absorbance at 555 nm (Method B). In both methods, the amount of CAT reacted corresponds to the amount of ZDV. The absorbance measured is found to increase linearly with concentration of ZDV. Under the optimum conditions, ZDV could be assayed in the concentration range 1.25-15.0 and 0.25-3.0 μg ML-1 by method A and method B, respectively. The apparent molar absorptivities are calculated to be 7.7x103 and 5.6x104 L mol-1 cm-1 for method A and method B, respectively, and the corresponding Sandell sensitivity values are 0.035 and 0.005 μg cm-2. The limits of detection and quantification are reported for both methods. Intra-day and inter-day precision and accuracy of the developed methods were evaluated as per the current ICH guidelines. The proposed methods can be readily utilized for bulk drug and in pharmaceutical formulations