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Accreditation and Quality Assurance: Journal for Quality, Comparability and Reliability in Chemical Measurement (v.12, #1)
Making the definitions of measurement units independent from arbitrary decisions (of worldly powers)
by Paul De Bièvre (pp. 1-2).
Evaluation of analytical instrumentation. Part XXII Instrumentation for liquid chromatography/mass spectrometry (pp. 3-11).
The reports of this series tabulate a number of features of analytical instruments that should be considered when making comparison between various systems. Scoring these features in a rational manner allows a scientific comparison to be made between instruments as an aid to selection. This is the XXIInd report of the series and deals with instrumentation for liquid chromatography/mass spectrometry.
Keywords: Instrumentation; Overview; Evaluation; Liquid chromatography/mass spectrometry
Characterisation of leather candidate certified reference materials for their mass fractions of aromatic amines by Jan-Willem Wegener; Haiko Schulz (pp. 12-20).
Three batches of leather samples were coloured with nine azo dyes that can yield eight proven or suspected carcinogenic aromatic amines under reduction conditions. The samples were milled to grains and bottled in jars. A group of five laboratories has established the mass fraction of the amines in a ring test using different analytical methods. The methods included a reduction step in order to cleave the azo dyes into the aromatic amines. Quantification was by standard addition: sub-samples of the leathers were spiked with known amounts of azo dyes of known purity. It was possible to establish the mass fractions of six of the eight aromatic amines in three of the leather samples.
Keywords: Leather; Aromatic amines; Azo dyes; Reference material; Ring test
The assessment of electronic balances for accuracy of mass measurements in the analytical laboratory by A. Gustavo González; M. Ángeles Herrador (pp. 21-29).
The accuracy of mass measurements when using electronic balances is considered within the frame of analytical assays in terms of the uncertainty budget according to the internal quality control routine, the calibration process, the balance specifications, and the weighing scenarios. Buoyancy corrections for both conventional and true mass are fully discussed. The procedure is illustrated with a worked example.
Keywords: Balance assessment; Weighing accuracy; Mass uncertainty; Balance calibration; Buoyancy correction
Development of an automatic static volumetric method based on loop injection by Friedrich A. Lagler; Michel O. Gerboles; Annette Borowiak (pp. 30-38).
A prototype of an automatic static volumetric method based on the injection of a pure compound by means of a loop instead of a manual syringe was constructed, fitting for both laboratory use and field applications. The crucial point, the evaluation of the loop volumes, was solved developing two techniques allowing traceability to SI units. Gas mixtures of nitrogen monoxide (NO) in nitrogen in the 10−9 V/V range and carbon monoxide (CO) in air in the 10−6 V/V range were generated and successfully compared to other primary calibration techniques. Relative expanded uncertainties (k=2) of 1.1% (compared to 0.8% of the manual static volumetric method [1]) for NO gas mixtures and 0.3% CO gas mixtures were estimated.
Keywords: Gas analysis; Static volumetric method; Primary reference gas mixture; Loop volume; Uncertainty calculation
Some Latin American experiences concerning teaching of chemical metrology by M. Alvarez Prieto; J. Jiménez Chacón; I. Cortés Nodarse; N. Martínez Alfonso (pp. 39-44).
In this paper, 15 years of the experiences acquired concerning the teaching of chemical metrology in Latin America are presented. These include postgraduate and undergraduate activities developed in eight countries. The combination of theoretic and practical activities and the sequence of learning from metrological, statistical, and chemometrical backgrounds up to practical activities in personal computers are basic and motivate the learning process. Care is taken to promote the metrological approach and thinking in analytical chemistry. The learning of computing techniques plays an important role, combining graphic and numerical techniques for data analysis. The role of examples during the teaching process is analyzed and recognized. The introduction of a general model of errors permits one to approach different topics on a metrological basis. The metrological approach of uncertainty based on the theory of errors permits one to develop the topic. Undergraduate students acquire a basic metrological knowledge and other experiences are also presented. Recommendations for undergraduate and postgraduate programs are pointed out.
Keywords: Chemical metrology teaching; Analytical chemistry learning; Quality assurance teaching; Postgraduate teaching; Undergraduate teaching
Understanding the meaning of accuracy, trueness and precision by Antonio Menditto; Marina Patriarca; Bertil Magnusson (pp. 45-47).
Clear definitions of basic terms, used to describe the quality of measurements, is essential for communication among scientists as well as when reporting measurement results to clients. Even if appropriate definitions are given in international standards and guidelines, the understanding of some basic terms sometimes proves difficult. The reasons for this are various, e.g., the same words being defined rather differently in encyclopaedias and in international standards as well as concepts, well established in some languages, that may be relatively new in other national communities and at large in the international one. Here we present a matrix intended to clarify the relationships between the type of error affecting an analytical measurement, the respective qualitative concepts (performance characteristics) and their quantitative expression.
Keywords: Terminology; Accuracy; Trueness; Precision
Training Course “Selection and Use of Reference Materials”, IRMM, Geel, 3–4 October 2006 by Thomas Linsinger; Marta Dabrio; Hendrik Emons; Andrea Held; Andrée Lamberty; Marina Ricci; Heinz Schimmel; Stefanie Trapmann (pp. 48-48).
The training course “Selection and use of reference materials” held at IRMM is described. This course dealt with practical and theoretical issues in the use of reference materials.
Publication of chemical research: do we need ethical standards? by Bo Karlberg (pp. 49-50).
Recently the European Association for Chemical and Molecular Sciences (EuCheMS) issued ethical guidelines for publications in journals and reviews. The diverging motives of authors, reviewers, and editors require agreed standards for participating in the publishing process. This implies the necessity to define ways how to handle allegations of misconduct and to react on actual violation of the consent.
Keywords: Ethical standards; Guidelines; Publications
Les Kirkup, Bob Frenkel: An Introduction to uncertainty in measurement using the GUM (Guide to the expression of uncertainty in measurement)
by David Brynn Hibbert (pp. 51-52).
Evaluation of the limit of performance of an analytical method based on a statistical calculation of its critical concentrations according to iso standard 11843: Application to routine control of banned veterinary drug residues in food according to European Decision 657/2002/EC
by E. Verdon; D. Hurtaud-Pessel; P. Sanders (pp. 54-54).