title: A reversed-phase high-performance liquid chromatographic assay for the determination of N-acetylcysteine in aqueous formulations.
abstract: A stability-indicating assay is described for the determination of N-acetylcysteine in aqueous pharmaceutical formulations. The sample is diluted to an appropriate concentration with dilute aqueous orthophosphoric acid. An aliquot of the solution, containing added l-tyrosine as an internal standard, is chromatographed using a 10-mum C(18) stationary phase with dilute orthophosphoric acid (pH 2.0) containing 0.5% w/v of sodium perchlorate as the mobile phase. The assay, which has a relative standard deviation of about 0.8%, can also be used as a test for related impurities in N-acetylcysteine. It is also suitable for determining the N-acetylcysteine content of the drug substance.
authors.affiliation: Glaxo Group Research Ltd, Ware, Hertfordshire, SG12 ODJ, UK.
authors.forename: J
authors.initials: J
authors.lastname: Farquhar
authors.forename: G
authors.initials: G
authors.lastname: Finlay
authors.forename: P A
authors.initials: PA
authors.lastname: Ford
authors.forename: M
authors.initials: M
authors.lastname: Martin-Smith