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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.12, #10)
Uncertainty from sampling, in the context of fitness for purpose by Michael H. Ramsey; Michael Thompson (pp. 503-513).
Sampling is an integral part of nearly all chemical measurement and often makes a substantial or even a dominant contribution to the uncertainty of the measurement result. In contrast with analysis, however, the uncertainty contribution from sampling has usually been ignored. Indeed, far less is known about sampling uncertainty, although in some application sectors it is known to exceed the analytical uncertainty, especially when raw materials (natural or industrial) are under test. In 1995 the authors of this paper proposed a framework of concepts and procedures for studying, quantifying, and controlling the uncertainty arising from the sampling that normally precedes analysis. Many of the ideas were based on analogy with well-established procedures and considerations relating to quality of analytical measurement, ideas such as validation of the sampling protocol, sampling quality control and fitness for purpose. Since that time many of these ideas have been explored experimentally and found to be effective. This paper is a summary of progress to date.
The intention of truth, objectivity and metrology by Günther Meinrath (pp. 515-523).
This manuscript will provide some food for thought. The major intention is to arm metrologically oriented chemists with a few arguments underpinning the importance of the seemingly exaggerated efforts spent on the lofty concept of objectivity and the fata morgana of true values. In fact, the intention of truth and objectivity, both utopian concepts, are the fundament of modern science. Objectivity demands to evaluate an estimate of uncertainty with each measurement result. It is not only a personal attitude towards an observation, but it also refers to the language used to communicate about this observation. The uniqueness of science as an approach to explain the physical world surrounding us is based on logic, objectivity and experiment. The importance of and the problem with spoken language as a tool to communicate about experiments is difficult to overestimate. Logical reasoning alone is not capable of generating insight in a similar way to what science has achieved. Measurement and objectivity are the decisive components of turning philosophy into a scientific process.
Keywords: Objectivity; Logical reasoning; Measurement uncertainty; True values
Replicated observations in metrology and testing: modelling repeated and non-repeated measurements by Franco Pavese (pp. 525-534).
In order to choose the right statistical tool, a basic issue for an accurate analysis of each specific problem is to understand whether the set of replicated measurement results under examination is to be considered as pertaining to repeated measurements or not. This issue is particularly important, since most of the traditional tools are valid only for repeated measurements, but, in many cases, such as laboratory comparisons (in metrology and in testing), the measurements necessary to assess correctly the measurand value and the associated uncertainty do not represent repeated measurements. The analysis performed in this paper aims to shine some light on these issues, starting with a review of the basic concepts, such as repeatability, reproducibility, accuracy, systematic error and bias, as defined in international documents and as used in the literature. The paper shows that, currently, a full consensus on a common language and understanding has not yet been achieved, and then shows how this fact reflects on the basic data models, especially those concerning inter-comparison data.
Keywords: Replicated measurements; Nomenclature; Repeatability; Reproducibility; Comparisons
Validation of the analytical procedure for the determination of polyaromatic hydrocarbons in smoke flavourings using high performance liquid chromatography coupled to an ultraviolet, diode array or fluorescence detector by Catherine Brasseur; François Brose; Alain Pirlot; Caroline Douny; Gauthier Eppe; Guy Maghuin-Rogister; Marie-Louise Scippo (pp. 535-542).
High performance liquid chromatography (HPLC) coupled to an ultraviolet (UV), diode array or fluorescence detector (UV/DAD/FLD) has been used to set up an analytical procedure for the quantification of 16 EU priority polyaromatic hydrocarbons (PAHs) in smoke flavourings. The following parameters have been determined for the 16 EU priority PAHs: limit of detection, limit of quantification, precision (repeatability and intermediate precision), recovery and measurement uncertainty, using the concept of accuracy profiles. They were in close agreement with quality criteria described in the Commission Regulation (EC) no. 627/2006 concerning PAHs in smoke flavourings.
Keywords: Polyaromatic hydrocarbons; PAH; HPLC/UV/FLD; Smoke flavouring; Analytical procedure validation; Accuracy profile; Uncertainty measurement
Determination of the furaltadone metabolite 5-methylmorpholino-3-amino-2-oxazolidinone (AMOZ) using liquid chromatography coupled to electrospray tandem mass spectrometry during the nitrofuran crisis in Portugal by Jorge Barbosa; Maria Luz Ferreira; Fernando Ramos; Maria Irene Noronha da Silveira (pp. 543-551).
The use of nitrofuran veterinary drugs as antibacterial compounds in food-producing animals has been banned in the EU since 1995. As nitrofurans are extensive and rapidly metabolized, control of their illegal use in animal production must be done in edible tissues by LC-MS/MS analysis in order to determine persistent tissue-bound metabolites. The introduction during 2002 of the multi-residue detection of nitrofuran tissue-bound metabolites by LC-MS/MS for nitrofuran control in Portuguese Residues Monitoring Plan, revealed the presence of 5-morpholinomethyl-3-amino-2-oxozolidinone (AMOZ), the bound residue of furaltadone, in a large number of samples, namely in meat poultry samples. From the 226 analysed samples in the last 4 months of 2002, 78 were non-compliant due to the presence of AMOZ (61 broilers, 11 turkeys, 5 quails and 1 pig). In this context, the aim of this paper is to describe the analytical data obtained on meat samples collected from various animal species under official Portuguese control for nitrofuran drug residues during the so-called “Portuguese nitrofuran crisis”.
Keywords: Nitrofurans; Residue determination; Furaltadone metabolite; Meat; LC-MS/MS
Metrology and protometrology: the ordinal question by René Dybkaer (pp. 553-557).
Laboratory medicine provides results for quantities as well as for properties having no magnitude. The terminology of the latter is less well established and sources are contradictory. Two recent papers on “protometrology” published in this journal offer an opportunity to discuss the necessary concept systems. The delineations of “metrology” versus “protometrology”, “observation” versus “measurement”, and the generic division of “property” are examined with emphasis on avoiding conflict with the International Vocabulary of Metrology. It is suggested that having “examination” as a top generic concept coupled with systematic modifiers for division, especially ‘nominal’ and ‘ordinal’, is a preferable terminological solution.
Keywords: Metrology; Protometrology; Observation; Nominal property; Examination