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

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

Rapid titrimetric and spectrophotometric methods for salbutamol sulphate in pharmaceuticals using N-bromosuccinimide

One titrimetric and two spectrophotometric methods which are simple, sensitive and rapid are described for the assay of salbutamol sulphate (SBS) in bulk drug and in tablet dosage forms using N-bromosuccinimide (NBS) and two dyes, rhodamine-B and methylene blue, as reagents. In titrimetry, aqueous solution of salbutamol sulphate is treated with a measured excess of NBS in acetic acid medium and after the oxidation of SBS is complete, the unreacted oxidant is determined iodometrically. Spectrophotometric methods entail addition of a known excess of NBS in acid medium followed by the determination of residual oxidant by reacting with a fixed amount of either rhodamine B and measuring the absorbance at 555 nm (method A) or methylene blue and measuring the absorbance at 665 nm (method B). In all methods, the amount of NBS reacting corresponds to the amount of SBS content. Titrimetric method is applicable over 1.74 × 10-4 – 8.68 × 10-4 mol L-1 range and the reaction stoichiometry is found to be 1:6 (SBS:NBS). In spectrophotometric methods, the absorbance is found to increase linearly with the concentration of SBS, which is corroborated by the correlation of coefficients of 0.9993 and 0.9988 for method A and method B, respectively. The systems obey Beer’s law for 0.25-1.75 mg mL-1 (method A) and 0.5-5.0 mg mL-1 (method B). The calculated apparent molar absorptivity values were found to be 2.10 × 105 and 6.16 × 104 L mol-1 cm-1, for method A and method B, respectively. The limits of detection and quantification are also reported for both spectrophotometric methods. Intra-day and inter-day precision and accuracy for the developed methods were evaluated. The methods were successfully applied to the assay of SBS in tablet and capsule formulations and the results were statistically compared with those of a reference method. No interference was observed from common tablet adjuvants. The accuracy and reliability of the methods were further ascertained by recovery experiments via the standard-addition technique

Iodometric determination of milligram and microgram amounts of levocetirizine in pharmaceuticals

Four simple, selective and sensitive methods are described for the determination of levocetirizine dihydrochloride (LCT) in bulk drug and in tablets. The methods exploit the well-known analytical reaction between iodide and iodate in the presence of acid solution. Iodide present is oxidized by iodate in an amount equivalent to the HCl present in LCT to iodine and the liberated iodine is determined by four different procedures which inturn quantify LCT at varying detection range and sensitiveness. Two direct titrimetric procedures involve titration of iodine by thiosulphate either towards starch end point (method A) or potentiometrically (method B). Both the methods have a reaction stiochiometry of 1: 1 (LCT: liberated iodine) and have quantification ranges of 2–20 mg LCT for method A and method B. The liberated iodine is also measured spectrophotometrically at 350 nm (method C) or the iodine-starch complex measured at 570 nm (method D). In both the methods, the absorbance is found to be linearly dependent on the concentration of iodine which in turn is related to LCT concentration. The calibration curves are linear over 5–40 and 1.25–12.5 mg mL−1 LCT for method C and method D, respectively. The calculated molar absorptivity and Sandel sensitivity values are 1.0 × 104 L mol−1 cm−1 and 0.0435 mg cm−2, respectively for method C, and their respective values for method D are 2.9 × 104 L mol−1 cm−1 and 0.0156 mg cm−2. The intra-day and inter-day accuracy and precision studies were carried according to the ICH guidelines. The method was successfully applied to the analysis of two brands of tablets LCT. The accuracy was also checked by placebo blank and synthetic mixture analyses besides recovery study via standard addition procedure