Abstract
A spectrophotometric method for the selective determination of paracetamol based on its reaction with pyrochatechol violet under basic conditions to form an ion-pair complex is described. The absorption maximum of the coloured ion-pair formed is observed at 652 nm and the molar absorptivity is 4.54 x10-3l mol-1 cm-1. Beer's law is obeyed over the concentration range 0.5-34.0 μg ml-1, while that obtained using Ringbom method is in the range 3.5 -32.0 μg ml-1. There is no interference from common additives, excipients and commercial drugs present in their formulations suggesting a highly selective procedure compared with others. Statistical analysis of the obtained results showed that there is, no significant difference and absence of any systematic error in the method compared with the official one. The method is simple, rapid and convenient and was applied successfully to the determination of paracetamol in pure and in its dosage forms compared with the official method.
Highlights
Abstract:- A spectrophotometric method- for the selective determination of paracetamol based on its reaction with pyrochatechol violet under basic conditions to form an ion-pair complex is described
Paracetamol (N-acetyl-4-aminophenol) occupies a prominent position amongst the extensively employed antipyretic analgesics. It is frequently formulated in drugs with acetyl salicylic acid, salicylamide, caffeine, codeine phosphate, phenyl propanolamine HCl, analgin and oxyphenbutazone
Stock solutions of 500 pg ml-' paracetamol, anhydrous caffeine, analgin, phenyl propanolamine HCl, chlorpheniramine maleate, acetyl salicylic acid, codeine phosphate or oxyphenbutazone were prepared by dissolving the respective standard compound in water
Summary
All experiments were performed with analytical grade chemical. Doubly distilled water was used throughout. 5 x 10') M stock solution of pyrocatechol violet (Aldrich product) was prepared by dissolving 0.1932 g in bidistilled water and completed to the mark in a 100 ml calibrated flask with water. Stock solutions of 500 pg ml-' paracetamol, anhydrous caffeine, analgin, phenyl propanolamine HCl, chlorpheniramine maleate, acetyl salicylic acid, codeine phosphate or oxyphenbutazone were prepared by dissolving the respective standard compound in water. Standard compounds were obtained from ICN Biomedical products. Stock solutions were stored below 6.0 "C in the dark. Solutionsofthe desired concentration were obtained by diluting the stock solutions to volume with water. A borate buffer solutions of pH 5.5 to 10.5were prepared as recommended previous~ylY(). All spectral measurements were made using a Perkin-Elmer 7r3B and the pH of the solutions was checked using an Orion Research Model 601AIDigital Ionlyzer
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