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Interlaboratory study of a NACE method for the determination of R ‐timolol content in S ‐timolol maleate: Assessment of uncertainty
Author(s) -
Marini Roland Djang'eing'a,
Groom Carl,
Doucet François R.,
Hawari Jalal,
Bitar Yaser,
Holzgrabe Ulrike,
Gotti Roberto,
Schappler Julie,
Rudaz Serge,
Veuthey JeanLuc,
Mol Roelof,
Somsen Govert W.,
de Jong Gerhardus J.,
Ha Pham Thi Thanh,
Zhang Jie,
Van Schepdael Ann,
Hoogmartens Jos,
Briône Willy,
Ceccato Attilio,
Boulanger Bruno,
Mangelings Debby,
Vander Heyden Yvan,
Van Ael Willy,
Jimidar Ilias,
Pedrini Matteo,
Servais AnneCatherine,
Fillet Marianne,
Crommen Jacques,
Rozet Eric,
Hubert Philippe
Publication year - 2006
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500832
Subject(s) - timolol , repeatability , reproducibility , chromatography , chemistry , replicate , mathematics , statistics , analytical chemistry (journal) , medicine , intraocular pressure , ophthalmology
Analyses of statistical variance were applied to evaluate the precision and practicality of a CD‐based NACE assay for R ‐timolol after enantiomeric separation of R ‐ and S ‐timolol. Data were collected in an interlaboratory study by 11 participating laboratories located in Europe and North America. General qualitative method performance was examined using suitability descriptors ( i.e. resolution, selectivity, migration times and S/N), while precision was determined by quantification of variances in the determination of R ‐timolol at four different impurity levels in S ‐timolol maleate samples. The interlaboratory trials were designed in accordance with the ISO guideline 5725‐2. This allowed estimating for each sample, the different variances, i.e. between‐laboratory ( s 2 Laboratories ), between‐day ( s 2 Days ) and between‐replicate ( s 2 Replicates ). The variances of repeatability ( s 2 r ) and reproducibility ( s 2 R ) were then calculated. The estimated uncertainty, derived from the precision estimates, seems to be concentration‐dependent above a given threshold. This example of R ‐timolol illustrates how a laboratory can evaluate uncertainty in general.