  Precision study on capillary electrophoresis methods for metacycline; ; et al in Electrophoresis (2006), 27(12), 2317-2329 A CE method for metacycline (MTC) determination was investigated in an inter-laboratory experiment. Many problems were encountered in this study, most of which were related to the transfer of the method ... [more ▼] A CE method for metacycline (MTC) determination was investigated in an inter-laboratory experiment. Many problems were encountered in this study, most of which were related to the transfer of the method to different CE equipment. The reported problems could be classified into different categories: problems related to the precision, to the parameters in the protocol, and to the MTC peak shape. As the peak shape problem was partially responsible for the poor precision, a new CE method was developed in order to obtain a good MTC peak shape on all equipment. The precision of this new method for MTC determination was examined in an intermediate precision study, where the influence of the factors "time" and "equipment" was investigated. Although the new method could be transferred to different instruments, the precision remained poor mainly due to the contributions of the between-replicate and the between-injection variances. [less ▲] Detailed reference viewed: 11 (1 ULg)Interlaboratory study of a NACE method for the determination of R-timolol content in S-timolol maleate: assessment of uncertainty.Marini Djang'Eing'A, Roland  ; ; et alin Electrophoresis (2006), 27(12), 2386-99 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 ... [more ▼] 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 (s2(Laboratories)), between-day (s2(Days)) and between-replicate (s2(Replicates)). The variances of repeatability (s2r) and reproducibility (s2R) 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. [less ▲] Detailed reference viewed: 55 (12 ULg)Precision study on capillary electrophoresis methods for metacycline.; ; et al in Electrophoresis (2006), 27(12), 2317-29 A CE method for metacycline (MTC) determination was investigated in an inter-laboratory experiment. Many problems were encountered in this study, most of which were related to the transfer of the method ... [more ▼] A CE method for metacycline (MTC) determination was investigated in an inter-laboratory experiment. Many problems were encountered in this study, most of which were related to the transfer of the method to different CE equipment. The reported problems could be classified into different categories: problems related to the precision, to the parameters in the protocol, and to the MTC peak shape. As the peak shape problem was partially responsible for the poor precision, a new CE method was developed in order to obtain a good MTC peak shape on all equipment. The precision of this new method for MTC determination was examined in an intermediate precision study, where the influence of the factors "time" and "equipment" was investigated. Although the new method could be transferred to different instruments, the precision remained poor mainly due to the contributions of the between-replicate and the between-injection variances. [less ▲] Detailed reference viewed: 27 (9 ULg)Determination of uncertainty in a liquid chromatographic method for erythromycin from Interlaboratory study results; ; et al Conference (2003, May) Detailed reference viewed: 14 (4 ULg)Determination of uncertainty in analytical measurements from collaborative study results on the analysis of a phenoxymethylpenicillin sample; ; et al in Analytica Chimica Acta (2003), 481 The correct interpretation of a measurement result requires knowledge about its uncertainty. Depending on the conditions under which the analyst is operating, different operational definitions of ... [more ▼] The correct interpretation of a measurement result requires knowledge about its uncertainty. Depending on the conditions under which the analyst is operating, different operational definitions of uncertainty have been proposed. They include: within-laboratory uncertainty, reproducibility uncertainty, bias-included uncertainty and absolute uncertainty. Here we consider the evaluation of the reproducibility uncertainty derived from the results obtained in an inter-laboratory experiment. Nine laboratories participated in an inter-laboratory study for the analysis of phenoxymethylpenicillin. The analyses consisted of a Karl–Fischer water determination, an acid–base titration to assay phenoxymethylpenicillin and a liquid chromatography (LC) method to determine 4-hydroxyphenoxymethylpenicillin and other impurities. The experimental set-up allowed to obtain for each determination s2 r and s2L as estimates of the repeatability variance (σ2r ) and the between-laboratory variance (σ2L), respectively. The reproducibility uncertainties for the different assays were then derived from these estimates. [less ▲] Detailed reference viewed: 43 (3 ULg)Determination of uncertainty in analytical measurements: Collaborative study of the analysis of phenoxymethylpenicillin; ; et al Poster (2002, April) Detailed reference viewed: 12 (1 ULg) |
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