Determination of uncertainty in analytical measurements from collaborative study results on the analysis of a phenoxymethylpenicillin sample

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 ▲]

Objectives of analytical methods and objectives of validation : how to reconciliate them ?

Conference (2003)

Enantiomeric separation of aminoglutethimide by capillary electrophoresis using native cyclodextrins in single and dual systems

in Journal of Separation Science (2003), 26(6-7), 536-542

Aminoglutethimide (AGT) is one of the few examples of chiral drugs that can be enantioseparated by capillary electrophoresis using any of the three native cyclodextrins: alpha-, beta-, or gamma-CD. A ... [more ▼]

Aminoglutethimide (AGT) is one of the few examples of chiral drugs that can be enantioseparated by capillary electrophoresis using any of the three native cyclodextrins: alpha-, beta-, or gamma-CD. A complete resolution of the enantiomers of this compound in cationic form could be achieved with each of the three CDs, using a pH 3 phosphoric acid-triethanolamine buffer. Affinity constants for AGT enantiomers with the three native CDs were determined, confirming that the highest selectivity was given by gamma-CD while the strongest complexation was obtained with beta-CD. However, an opposite affinity pattern was observed with the latter. Selectivity was lower for AGT enantiomers in dual CD systems, compared to that obtained with a single selector at its optimal concentration, which confirms that dual systems are of more limited interest when the two selectors have a similar effect on the analyte mobility. These results are in good agreement with those predicted using recently developed mathematical models. [less ▲]

DEVELOPMENT AND VALIDATION OF A SIMULTANEOUS LC METHOD FOR THE DETERMINATION OF S-TIMOLOL MALEATE, ITS ANTIPODE AND RELATED SUBSTANCES USING A CELLULOSE BASED CHIRAL STATIONARY PHASE

Poster (2002, April)

Optimisation and validation of a generic method for the LC assay of six corticosteroids and salicylic acid in dermopharmaceutical forms

in Chromatographia (2002), 55(5-6), 263-269

A generic method was developed for the liquid chromatographic (LC) assay of six corticosteroids and salicylic acid in different dermatological formulations containing methylparaben and propylparaben or ... [more ▼]

A generic method was developed for the liquid chromatographic (LC) assay of six corticosteroids and salicylic acid in different dermatological formulations containing methylparaben and propylparaben or sorbic acid as preservatives. An adequate separation was obtained using octadecylsilica as stationary phase and a mixture of acetonitrile (MeCN) and 25 mM phosphate buffer of pH 3.5 as mobile phase. Segmented gradient elution was applied from 30 to 45% of MeCN in 9.9 minutes, then from 45 to 96% in 19.0 minutes. UV detection was performed at 240 nm. The method was validated. Very good results were obtained with respect to linearity selectivity, precision and accuracy. [less ▲]

Separation and simultaneous determination of S-timolol maleate, its optical antipode and related substances by liquid chromatography using a cellulose based chiral stationary phase

Conference (2001, May 25)

Development and validation of an LC method for the determination of six corticosteroids, salicylic acid and parabens in different pharmaceutical formulations

Conference (2000, April)

Development and validation of a LC method for the determination of bacitracin in a pharmaceutical dosage form

Conference (1999, May)