Extraction-spectrofluorimetric method for the determination of erythromycin and its esters in pharmaceutical formulations using manual and flow-injection procedures

Studies and analytical application of reaction of imipramine with chrome azurol S

Chrome azurol S (CAS) was tested as a spectrophotometric reagent for the determination of imipramine (IMP). It reacts in aqueous media with IMP forming pink-red, sparingly soluble in water ion association compound. This compound was quantitatively extracted with chloroform and the absorbance of organic phase was measured at 510 nm. The extraction conditions were studied using a batch method. On the basis of the results obtained with batch method, three-line flow-injection system was constructed. Batch and flow-injection methods were successfully applied for the determination of IMP in pharmaceutical preparation.

Spectrofluorimetric analysis of certain macrolide antibiotics in bulk and pharmaceutical formulations

The macrolides (erythromycin, erythromycin esters, azithromycin dihydrate, clarithromycin and roxithromycin) can be analyzed by a simple spectrofluorimetric method based on the oxidation by cerium(VI) in the presence of sulphuric acid and monitoring the fluorescence of cerium(III) formed at lambda(ex) 255 nm and lambda(em) 348 nm. All variables affecting the reaction conditions as cerium(VI), sulphuric acid concentrations, heating time, temperature and dilution solvents were carefully studied. Linear calibration graphs were obtained in the range of 42.6-1200 ng ml(-1) with a percentage relative standard deviation in the range of 0.014-0.058%. Quantitation and detection limits were calculated. The method was applied successfully for the assay of the studied drugs in pure and pharmaceutical dosage forms as tablets, capsules and suspension. Recovery experiments revealed recovery of 98.3-100.8%. The effect of potential interference due to common ingredients as glucose, sucrose, lactose, citric acid, and propylene glycol was investigated. Applying standard addition method shows a recovery of 97.7-100.9% macrolide antibiotics from their corresponding dosage forms.

Selective spectrophotometric method for the determination of erythromycin and its esters in pharmaceutical formulations using gentiana violet

A simple and selective method for the determination of erythromycin and its stearate and succinate esters in their pure forms and in pharmaceutical formulations is described. The procedure is based on the formation of a blue-coloured (lambda max = 633 nm) complex with gentiana violet in alkaline medium. Different variables affecting the colour development were studied and optimized. The method was used to determine 2.5-25 micrograms ml-1 of erythromycin in the final measured solution. The simplicity of the method permits rapid analysis and it is thus suitable for routine control. The method is highly specific for the determination of stearate and succinate esters in pharmaceutical formulations. The reliability of the method was established by parallel determinations against the official British Pharmacopoeial method.