Avoid the perils of using rounded data.

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 it is not possible to use unrounded data (with many decimal places) then the authors recommend that the data used should have at least two decimal places more than the number of decimal places required in the reported value ("effectively unrounded data"). Examples are given to illustrate the importance of using effectively unrounded data in visualisation and numerical calculations. It is recommended that effectively unrounded data and, if required, reported data are listed in reports. The implications of using rounded data when making formal assessments against specification limits is also discussed and guidance is provided on the use of nominal and effective specification limits.

Method ruggedness studies incorporating a risk based approach: a tutorial.

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 performed upon transfer of a method to another laboratory, however, it can also be employed during method development when an assessment of the method's inherent variability is required. The use of a ruggedness study provides a more rigorous method for assessing method precision than a simple comparative intermediate precision study which is typically performed as part of method validation. Prior to designing a ruggedness study, factors that are likely to have a significant effect on the performance of the method should be identified (via a risk assessment) and controlled where appropriate. Noise factors that are not controlled are considered for inclusion in the study. The purpose of the study should be to challenge the method and identify whether any noise factors significantly affect the method's precision. The results from the study are firstly used to identify any special cause variability due to specific attributable circumstances. Secondly, common cause variability is apportioned to determine which factors are responsible for most of the variability. The total common cause variability can then be used to assess whether the method's precision requirements are achievable. The approach used to design and analyse method ruggedness studies will be covered in this tutorial using a real example.

Acceptance criteria for method equivalency assessments.

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 lifecycle. A method equivalence assessment is required when a change is made to a method which may pose a risk to its ability to monitor the quality of the process. Establishing appropriate acceptance criteria are a vital, but not clearly understood, prerequisite to deciding the appropriate design/sample size of the equivalency study. A number of approaches are proposed in the literature for setting acceptance criteria for equivalence which address different purposes. This perspective discusses those purposes and then provides more details on setting acceptance criteria based on patient and producer risk, e.g., tolerance interval approach and the consideration of method or process capability. Applying these to a drug substance assay method for batch release illustrates that, for the equivalence assessment to be meaningful, a clear understanding and appraisal of the control requirements of the method is needed. Rather than a single exact algorithm, the analyst's judgment on a number of aspects is required in deciding the appropriate acceptance criteria.

Design and analysis of method equivalence studies.

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 equivalency study, an acceptance criterion (an acceptable bias between original and modified/changed method) must be chosen. The choice of acceptance criteria requires the identification of the smallest mean difference or bias between methods that is practically important. Equivalence testing in this manner is used to prove that the new method can generate data which continues to support previously established specifications. Once the acceptance criterion is decided, other aspects of the study can be designed following a set of design principles. When the design and acceptance criteria have been established, the collection of the data can commence. Demonstration of equivalence should not start until the validity of the observations has been confirmed such as assessment for outliers, normality, and comparison of variances. Once the suitability of the data is confirmed, the mean difference between the two data sets can be calculated along with a +/-90% confidence interval using the TOST approach. It can then be established whether equivalence of the two methods has been demonstrated.

Trace level impurity method development with high-field asymmetric waveform ion mobility spectrometry: systematic study of factors affecting the performance.

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 little prior knowledge of the factors or their settings is available. We present the results of an investigation performed in order to obtain a better understanding of the FAIMS technology. The influence of eight factors (polarity of dispersion voltage, outer bias voltage, total gas flow rate, composition of the carrier gas (e.g. %He), outer electrode temperature, ratio between the temperatures of the inner and outer electrodes, flow rate and composition of the make-up mobile phase) was assessed. Five types of responses were monitored: value of the compensation voltage (CV), intensity, width and asymmetry of the compensation voltage peak, and resolution between two peaks. Three types of studies were performed using different test mixtures and various ionisation modes to assess whether the same conclusions could be drawn across these conditions for a number of different types of compounds. To extract the maximum information from as few experiments as possible, a Design of Experiment (DoE) approach was used. The results presented in this work provide detailed information on the factors affecting FAIMS separations and therefore should enable the user to troubleshoot more effectively and to develop efficient methods.

Development, validation and transfer into a factory environment of a liquid chromatography tandem mass spectrometry assay for the highly neurotoxic impurity FMTP (4-(4-fluorophenyl)-1-methyl-1,2,3,6-tetrahydropyridine) in paroxetine active pharmaceutical ingredient (API).

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 control environment. The method was developed to achieve a detection limit of 10ppb mass fraction of FMTP in paroxetine API. An LC-MS/MS method was chosen because it provided the required sensitivity and selectivity with minimal sample preparation. This paper discusses the issues with transferring such complex methodology to a production environment. Linearity, repeatability and reproducibility of the method were demonstrated. This work shows that it is possible using the same approach that would be used for the transfer of any analytical method from R&D to a manufacturing environment.

Investigation into the factors affecting accuracy of mass measurements on a time-of-flight mass spectrometer using Design of Experiment.

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 reference compounds, quality of calibration, number of reference acquisitions averaged and TDC (time-to-digital converter) settings (resolution, Np multiplier (number of pushes correction factor), minimum number of points, i.e. minimum acquisition width which defines a peak). To extract the maximum information from as few experiments as possible, a Design of Experiment approach was used. The data will be used as a basis for developing guidance on accurate mass measurement on q-oaToF instruments.