Marion J. Chatfield

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Method equivalence assessments should be considered when analytical methods are either modified or substituted. The TOST (two one sided tests) approach provides a sounder data driven method for testing equivalence than a simple comparative intermediate precision study which is typically performed as part of method validation. Prior to designing an(More)
The results of an investigation of the parameters which have the most significant effect on the accuracy of mass measurements on a quadrupole orthogonal acceleration time-of-flight mass spectrometer (q-oaToF) are reported. The influence of eight factors is investigated: ion abundances of reference and analyte compounds, mass difference between analyte and(More)
This work describes the development of a liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for a highly toxic impurity, FMTP (4-(4-fluorophenyl)-1-methyl-1,2,3,6-tetrahydropyridine), in paroxetine active pharmaceutical ingredient (API), followed by the subsequent validation of the methodology and transfer into a global production/quality(More)
From a purely technical point of view it is always better to work with recorded/unrounded data. This paper discusses reasons why despite this, rounded data used for reporting may have been used in the past in calculations and visualisation. If rounded data are used then it is recommended that a risk assessment of the impact of the rounding is performed. If(More)
Quality by design (ICH-Topic Q8) requires that process control strategy requirements are met and maintained. The challenging task of setting appropriate acceptance criteria for assessment of method equivalence is a critical component of satisfying these requirements. The use of these criteria will support changes made to methods across the product(More)
A Hogarth, or 'wicked', universe is an irregular environment generating data to support erroneous beliefs. Here, we argue that development scientists often work in such a universe. We demonstrate that exploring these multidimensional spaces using small experiments guided by scientific intuition alone, gives rise to an illusion of validity and a misplaced(More)
This tutorial explains how well thought-out application of design and analysis methodology, combined with risk assessment, leads to improved assessment of method ruggedness. The authors define analytical method ruggedness as an experimental evaluation of noise factors such as analyst, instrument or stationary phase batch. Ruggedness testing is usually(More)
For the determination of trace level impurities, analytical chemists are confronted with complex mixtures and difficult separations. New technologies such as high-field asymmetric waveform ion mobility spectrometry (FAIMS) have been developed to make their work easier; however, efficient method development and troubleshooting can be quite challenging if(More)
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