Trends in quality in the analytical laboratory. I. Traceability and measurement uncertainty of analytical results (original) (raw)

New advances in method validation and measurement uncertainty aimed at improving the quality of chemical data

Analytical and Bioanalytical Chemistry, 2004

The implementation of quality systems in analytical laboratories has now, in general, been achieved. While this requirement significantly modified the way that the laboratories were run, it has also improved the quality of the results. The key idea is to use analytical procedures which produce results that fulfil the users’ needs and actually help when making decisions. This paper presents the implications of quality systems on the conception and development of an analytical procedure. It introduces the concept of the lifecycle of a method as a model that can be used to organize the selection, development, validation and routine application of a method. It underlines the importance of method validation, and presents a recent approach based on the accuracy profile to illustrate how validation must be fully integrated into the basic design of the method. Thanks to the β-expectation tolerance interval introduced by Mee (Technometrics (1984) 26(3):251–253), it is possible to unambiguously demonstrate the fitness for purpose of a new method. Remembering that it is also a requirement for accredited laboratories to express the measurement uncertainty, the authors show that uncertainty can be easily related to the trueness and precision of the data collected when building the method accuracy profile.

Trends in quality in the analytical laboratory. II. Analytical method validation and quality assurance

TrAC Trends in Analytical Chemistry, 2004

It is internationally recognized that validation is necessary in analytical laboratories. The use of validated methods is important for an analytical laboratory to show its qualification and competency. In this update on analytical quality, we place validation of analytical methodologies in the broader context of quality assurance (QA). We discuss different approaches to validation, giving attention to the different characteristics of method performance. We deal with the concepts of single-laboratory or in-house validation, inter-laboratory or collaborative study, standardization, internal quality control (IQC), proficiency testing (PT), accreditation and, finally, analytical QA (AQA).

Assuring Quality of Analytical Measurement Results: The IUPAC Role

Chemistry International -- Newsmagazine for IUPAC, 2007

The IUPAC Role by Ales Fajgelj O ver the past 30 years the value of world trade has risen dramatically. In 2005 it amounted to almost USD 17 trillion (trillion = 10 12 ; see figure 1). A large proportion of this trade is dependent upon chemical analyses, since food, pharmaceutical products, medicines, ores, and chemical products in general represent the largest groups of trading items. To gain acceptance in the trading process, the quality of analytical measurement results needs to be assured and demonstrated. The term quality of analytical measurement results encompasses, among others, comparability of analytical results, their accuracy, reproducibility, metrological traceability, measurement uncertainty, and more.

The traceability of analytical measurements

Accreditation and Quality Assurance, 1997

Traceability to the System International (SI) is an important prerequisite for international comparability and uniformity of chemical measurements to ensure mutual recognition of the results. In theory, all measurements can be traced back to the seven base units of the SI. Although the traceability system works well for most physical measurements, in many analytical and in some spectrophotometric measurements this system is not satisfactory. This paper describes the particular and practical problems and the contribution of the Romanian National Institute of Metrology in this field. The paper discusses the following concepts: clearly defined targets in the form of requirement specification, knowledge of trueness and/or measurement uncertainty, and traceability through an unbroken chain of calibration to primary standards. Traceability and uncertainty being two concepts inherently coupled, two examples of assessment of the uncertainty of measurement results are given for two spectrophotometric methods currently used in chemical laboratories.

Is traceability an exclusive property of analytical results? An extended approach to traceability in chemical analysis. Author's reply

Fresenius Journal of Analytical Chemistry, 1997

The need to adapt the definition of traceability in the Metrological Dictionary of ISO to the growing use of this concept in Analytical Chemistry aroused the broader, more flexible proposal expounded in this paper which aims to be closer to the bench level. The traceability concept is addressed in a hierarchical manner by ranking the different notions to which the qualifier "traceable" applies (results, standards, equipment and samples) in such a way that it is compatible with the ISO definition. Relationships among them and with classical analytical properties are also exposed.

Reliability of analytical information in the XXIst century

Anal Chim Acta, 1999

One of the most relevant bottlenecks of the progress of analytical sciences is the existence of adequate references in general and, in particular, of measurement standards for analytical processes and their proper use in the context of metrology in chemistry. Keywords such as traceability, uncertainty, calibration, etc. are crucial to characterise the analytical information. All of them can be summarised by using reliability as an overall analytical attribute. The main aim of this paper is the systematic consideration of this basic approach among the trends in Analytical Chemistry, particularly in qualitative analysis.