The ongoing progress of science has shown that it is important for analytical scientists to determine not only the presence of particular elements, but also their species. There are many fields where this is applicable, and where there are a number of topics to be addressed. Developing separation and measurement systems for the many element species has tested the resourcefulness of analytical chemists over recent decades. A product of the EU sponsored Speciation 21 Network, this book presents a detailed review of the state-of-the-art of speciation issues in the occupational health, food and environment sectors, along with the main conclusions arising from discussions held during expert meetings. Topics covered include mercury and organotin compounds in the environment; factors affecting the health of workers; the importance of speciation of trace elements for health, and subsequent metabolism in the body; analytical methodologies; risk assessment; and legislation. Trace Element Speciation for Environment, Food and Health provides an insight into applied research in the speciation field and how it has become so important in all the fields represented. With its comprehensive coverage, it will be of particular interest to researchers in industry and academia, as well as government agencies and legislative bodies.
Trace Element Speciation for Environment, Food and Health
By Les Ebdon, Les Pitts, Rita Cornelis, Helen Crews, O.F.X. Donard, Philippe QuevauvillerThe Royal Society of Chemistry
Copyright © 2001 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-0-85404-459-7Contents
Foreword Philippe Quevauviller, v,
IUPAC Definitions for Terms Related to Chemical Speciation and Fractionation of Elements Rita Cornelis, ix,
List of Abbreviations, xxiii,
Contributors, xxv,
General Aspects,
Chapter 1 Accuracy and Traceability in Speciation Analysis Philippe Quevauviller, 3,
Chapter 2 Quality Control in Speciation Analysis Erwin Rosenberg and Freek Ariese, 17,
Chapter 3 Sample Treatment and Storage in Speciation Analysis J.L. Gómez-Ariza, E. Morales, I. Giráldez, and D. Sánchez-Rodas, 51,
Chapter 4 Aspects of the Threshold Limit Concept Bernd Neidhart, 81,
Chapter 5 Considerations of the Legislative Aspects of the Data Quality Requirements in Trace Element Analysis Roger Wood and Helen Crews, 93,
Environment,
Chapter 6 Metal Speciation for Improved Environmental Management O. F. X. Donard, 115,
Chapter 7 Mercury – Do We Know Enough? Milena Horvat, 127,
Chapter 8 Organotin Compounds in the Environment: Still a Critical Issue O. F. X. Donard, G. Lespes, D. Amouroux and R. Morabito, 142,
Chapter 9 An Environmental Case History of the Platinum Group Metals Sebastien Rauch and Gregory M. Morrison, 176,
Chapter 10 Speciation in the Frame of Environmental Bio-monitoring – Challenges for Analytical and Environmental Sciences Hendrik Emons, 188,
Chapter 11 Arsenic Speciation in the Environment Péter Fodor, 196,
Chapter 12 Rapid Tests – A Convenient Tool for Sample Screening with Regard to Element Speciation Martina Unger-Heumann, 211,
Food,
Chapter 13 The Importance of Trace Element Speciation in Food Issues Helen M. Crews, 223,
Chapter 14 Trace Metal Speciation – A View from Inside the Food Industry Simon Branch, 228,
Chapter 15 Trace Element Speciation in Food: A Tool to Assure Food Safety and Nutritional Quality Peter Van Dael, 232,
Chapter 16 Arsenic Intake in the Basque Country (Spain): A Real Need for Speciation I. Urieta, M. Jalón and M. L. Macho, 241,
Chapter 17 Trace Element Speciation and International Food Legislation – A Codex Alimentarius Position Paper on Arsenic as a Contaminant Erik H. Larsen and Torsten Berg, 251,
Chapter 18 The Need for Speciation to Realise the Potential of Selenium in Disease Prevention Sven Moesgaard and Richard Morrill, 261,
Health,
Chapter 19 The Importance of Speciation of Trace Elements in Health Issues Rita Cornelis, 287,
Chapter 20 Occupational Health and Speciation Using Nickel and Nickel Compounds as an Example Sally Pugh Williams, 297,
Chapter 21 Surface Structure and Speciation of Metal Aerosols: A Key to the Understanding of Their Biological Effects Markku Huvinen, 308,
Chapter 22 The Importance of Chromium in Occupational Health Grant Darrie, 315,
Chapter 23 Speciation Related to Human Health Riánsares Muñoz-Olivas and Carmen Cámara, 331,
Chapter 24 Risk Assessment and Trace Element Speciation John H. Duffus, 354,
Overview,
Chapter 25 An Overview Les Ebdon and Les Pitts, 375,
Subject Index, 385,
CHAPTER 1
Accuracy and Traceability in Speciation Analysis
PHILIPPE QUEVAUVILLER
1 Introduction
Traceability issues are of increasing concern in all fields where chemical measurements form the basis for decisions. The concepts of accuracy and traceability as applied to environmental analysis are, however, still prone to misunderstanding. Some years ago, Horwitz stated that 'considerable evidence exists in the literature that few analytical chemists pay attention to the question of the reliability of the analytical results they produce. These chemists believe that a natural law exists in measurement science, that if the directions for conducting a measurement are followed, the true value necessarily results'. This corresponds to the long-term debate about precision or reproducibility over accuracy, which is now relayed by ongoing discussions on accuracy and traceability: while accuracy refers to the closeness of analytical values to 'true values' (trueness) and among various repetitions (precision), the term traceability implies a link between the data obtained and established references, through an unbroken chain of comparisons, all with stated uncertainties. Recent controversial discussions have illustrated the misunderstanding, which may occur among the analytical community with respect to accuracy and traceability issues in the area of speciation analysis, with possible consequences on environmental data interpretation.
Speciation analysis is no longer a new feature. IUPAC defines this term as 'the analytical activity of identifying and measuring the quantity of one or more individual chemical species in a sample'. The speciation of an element is defined as 'the distribution of defined chemical species of an element in a system'. Chemical species of some elements (e.g. organotins, organomercury compounds) are now included in the list of substances to be determined in the frame of international environmental programmes, requiring an increasing knowledge and care with respect to the quality control (including traceability issues) of all monitoring steps (from sampling to reporting data).
Analytical techniques used for the determination of chemical species are generally based on a succession of steps (e.g. extraction, derivatisation, separation, detection) all of which are prone to various sources of systematic errors. Within the last decade, international collaborative efforts (through inter-laboratory studies and certification of reference materials) have enabled the systematic study of hyphenated techniques used for the determination of chemical species of, e.g., arsenic, chromium, mercury, lead, tin and selenium in environmental matrices (water, fish or mussel tissues, sediments). The determination of operationally-defined element fractions (extractable forms of trace elements) in sediment and soil matrices has also been collaboratively studied, mainly to harmonise and standardise extraction schemes, in order to improve the comparability of data (stressing that, strictly speaking, this type of determination should not be covered by the term 'speciation'). In this context, all of these collaborative efforts have been understood as being directed towards the drive for accuracy (trueness and precision as defined below). It has been recognised recently that these achievements have actually led primarily to the establishment of reference points (e.g. certified values in reference materials), which do not necessarily correspond to 'true values', but offer a mean with which laboratories may compare their data internationally and, hence, achieve traceability. This ambiguity still generates confusion and misunderstanding among the scientific community. This chapter discusses this issue, focusing on analytical measurements only. Extending discussions on general traceability issues would imply an examination of steps prior to laboratory work (sampling, storage, etc.) which is beyond the scope of this contribution.
2 Accuracy
The accuracy concept covers the terms trueness and precision. Trueness is defined as 'the closeness of agreement...
