An isocratic RP-HPLC method for the determination of retinol and alpha-tocopherol in serum, with fluorescence and UV/VIS detection, respectively, was developed and validated according to international guidelines. Detection (retinol 0.015 mg/L, alpha-tocopherol 0.29 mg/L) and quantification (retinol 0.05 mg/L, alpha-tocopherol 0.95 mg/L) limits were determined. Repeatability was <3.3% and <2.9% and intermediate precision was <4.6% and <3.2%, for retinol and alpha-tocopherol, respectively. Certified reference materials were utilised to assess bias and guarantee traceability to SI units. Expanded uncertainties (retinol 8.9%; alpha-tocopherol 7.9%), estimated according to the EURACHEM/CITAC guide from method validation data, satisfied fit-for-purpose requirements based on biological variability.

For 3 days in October 2008, ''the eternal city'' became the global centre for proficiency testing (PT) and external quality assurance (EQA).Building on the success of their previous workshops, the EURACHEM Proficiency Testing Working Group organised the 6th Workshop on Proficiency Testing in Analytical Chemistry, Microbiology and Laboratory Medicine in association with EQALM and CITAC.The Workshop (www.iss.it/eurachem) was supported locally by several Italian organisations, including the public research institutes devoted to public health (ISS), metrology (INRIM), environmental protection (ISPRA) and innovative technologies (ENEA), as well as the accreditation bodies (SINAL, SINCERT & SIT) and the standardisation body for chemical industry (UNICHIM).This workshop once again provided an excellent opportunity for providers, users and regulators of PT/EQA to come together to discuss a wide range of key issues across the three disciplines of analytical chemistry, microbiology and laboratory medicine.With 244 delegates from 47 different countries attending, it ensured that discussions encompassed views on a global perspective.This included important contributions from a number of developing countries which was made possible by the support of delegates from these areas by IAEA, PTB and UNIDO.Many sectors face very similar issues with regards to PT/ EQA so this workshop provided an excellent and beneficial opportunity for cross-fertilisation of ideas.

External quality assessment schemes monitor laboratory performance and provide a stimulus for improvement in accuracy. However, monitoring of participant performance varies according to the scheme and can lead to conflicting conclusions. Quality specifications based on biological intra- and inter-individual variability were calculated and evaluated. For this purpose, results reported by laboratories participating in different copper, selenium and zinc schemes were evaluated using Z-scores and serum/plasma samples at key copper, selenium and zinc concentrations. Desirable quality specifications developed from the biological intra- and inter-individual variability were: +/- 0.56 mu mol/l or 8% of the assigned target concentration, whichever is the greater for Cu; +/- 0.8 mu mol/l or 10% of the assigned target concentration, whichever is the greater for Zn and +/- 0.048 mu mol/l or 8% of the assigned target concentration, whichever is the greater for Se. The performance of the participating laboratories depended on analyte, concentration but the percentages of failure were generally high. Desirable quality specifications based on biological variation are probably too severe for the current state-of-the-art of analytical methodologies applied by routine laboratories. Therefore, the members of the network propose to use for the moment the minimal quality specification which are +/- 0.84 mu mol/l or 12% of the assigned target concentration, whichever is the greater for Cu; +/- 1.2 mu mol/l or 15% of the assigned target concentration, whichever get concentration, whichever is the greater for Zn and +/- 0.072 mu mol/l or 12% of the assigned target concentration, whichever is the greater for Se.

BACKGROUND:Trace element external quality assessment schemes monitor laboratory performance and provide a stimulus for improvement in accuracy. However, monitoring of participant performance varies according to the scheme and can lead to conflicting conclusions.METHODS:Quality specifications based on biological intra- and interindividual variability were calculated and compared to those currently used by various trace element external quality assessment schemes for plasma or serum copper, zinc, and selenium concentrations. For this purpose, we evaluated results reported by participating laboratories in different schemes, at key concentrations, using z scores.RESULTS:Minimal quality specifications developed from the biological intra- and interindividual variability were, for Cu, +/-0.84 micromol/L or 12% of the assigned target concentration, whichever is greater; for Zn, +/-1.20 micromol/L or 15% of the assigned target concentration, whichever is greater; and for Se, +/-0.072 micromol/L or 12% of the assigned target concentration, whichever is greater. Reported performance of the participating laboratories depended on analyte, concentration, and the selected quality specification. In addition, the most commonly used methods for the determination of Cu, Zn, and Se may give different results.CONCLUSIONS:The proposed minimal quality specifications based on biological variation are generally slightly less stringent than those currently in use, although they do not drastically change the performance evaluation in the different schemes. These specifications are a first step in the harmonization of practices among the schemes and remain to be evaluated.

The European Council Directive 98/24 on the protection of the health and safety of workers exposed to chemical agents sets out provisions for environmental and biological monitoring, making specific reference to binding limit values and health surveillance measures for those with exposure to lead

Quality specifications (QS) are proposed for lead in blood and for aluminium, copper, selenium and zinc in serum as part of the aim to set standards of performance for laboratories so that results can be demonstrated to be fit for the purpose to which they are applied. The QS were established taking account of the analytical state-of-the-art, physiological variations in the concentrations of the analyte and the clinical purpose for which the assay is to be used. A procedure was devised that uses these QS to give equivalence of assessment among external quality assessment schemes (EQAS), thus avoiding conflicting information which has been demonstrated in the past. Advantages of this procedure are: to provide direct comparison of performance of laboratories taking part in different schemes, to provide equivalence of assessment of laboratory performance necessary to establish mutual recognition agreements, and to demonstrate the fitness for purpose of results from participants.

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.

A complex antioxidant system is present in human saliva, with uric acid being the most concentrated component. Ascorbic acid, present at low concentrations in saliva, is actively secreted into the gastric lumen. We report that ascorbic acid added to human saliva at pH 2 was consumed within a few minutes, regenerating HNO(2), whereas uric acid was consumed relatively slowly in a nitrite-dependent manner. The consumption of uric acid was (i) rapid under normoxic conditions and slower at low oxygen tensions, (ii) coupled to *NO release, (iii) linked to the decrease in nitrite consumption and in nitrate formation, and (iv) unaffected by the nitrosation catalyst thiocyanate. Both chlorogenic acid and bovine serum albumin, representative of a phenol- and a protein-rich meal, respectively, were able to spare uric acid, although chlorogenic acid increased, whereas bovine serum albumin inhibited, *NO release. We hypothesize that the major role of uric acid in saliva at pH 2 could be to preserve the stomach from the formation of toxic nitrogen species and that low levels of uric acid, together with ascorbic acid consumption, may contribute to the high occurrence of tumors at the gastroesophageal junction and cardia. The sparing effects of dietary compounds may therefore be an important not fully appreciated effect.

The results obtained by a laboratory over a number of proficiency testing/external quality assessment schemes (PT/EQAS) rounds can give information on the uncertainty of its measurements for a given test, provided that conditions such as full coverage of the routine analytical range, traceability, and small uncertainty of the assigned values (compared to the spread of the results) are met and provided that systematic deviations and any other sources of uncertainty are considered. As organisers of the Italian EQAS (ITEQAS) in occupational and environmental laboratory medicine, we tested this hypothesis using as model data from well-performing laboratories taking part in ITEQAS for lead in blood over the last 2 years. We also investigated how different PT/EQAS features (frequency of trials and number of samples) would affect a laboratory estimate of its uncertainty. Such information can be helpful in improving PT/EQAS organisation and define, for a given test: (a) the state of the art of the uncertainty of current measurement procedures, (b) identify needs for improvement of analytical methodologies and (c) set targets for acceptable uncertainty values.

Most people in any community come into contact with chemicals that are potentially harmful to their health. Some elements are essential to health and inadequate amounts in food may also lead to ill health. Measurement of chemicals in blood, urine or other specimens is a fundamental feature of studies undertaken in the field of Occupational and Environmental Laboratory Medicine (OELM). Results are used to assess the risk for either overexposure or deficiency of essential nutrients. External Quality Assessment Schemes (EQAS) aid laboratories to achieve accurate and consistent data and 11 organisers of EQAS in Europe and North America are working to improve the effectiveness of their activities. The aims of the Network of EQAS Organisers in OELM are to stimulate improvements in analytical results, establish equivalence of assessment among Schemes, collaborate to enhance the practice of EQA including whenever possible to warrant traceability of EQAS to primary standards.

The use of chemicals warrants many benefits on which modern society is entirely dependent. On the other hand, the lack of reliable information about the impact of the use of chemicals raises increasing concern. In order to guarantee the safety of chemicals it is mandatory to proceed to risk assessment, which in turn consists of hazard evaluation and exposure estimation. These activities are strictly dependent upon the availability of reliable data and information, produced by, e.g., test facilities, test laboratories and clinical laboratories, the specific competence of which has been properly recognised. All this applies in the pre-marketing phase as well as during the use of chemical substances. In this latter phase it is necessary to carry out an appropriate monitoring of environment, food and, in specific situations, human beings (biological monitoring). In the field of chemical safety, standards, legal instruments and operative instruments are nowadays available. These tools make it possible to assess both the quality of data and the competence of the entities involved in the production of the data themselves.

Vox SanguinisVolume 80, Issue 2 p. 121-121 Time-dependent increase of aluminium in human albumin solutions: the role of initial citrate content M. Orlando, M. Orlando Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorA. Menditto, A. Menditto Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorR. Sardelli, R. Sardelli Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorG. Lanzieri, G. Lanzieri Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorM. Orlando, M. Orlando Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this author M. Orlando, M. Orlando Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorA. Menditto, A. Menditto Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorR. Sardelli, R. Sardelli Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorG. Lanzieri, G. Lanzieri Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this authorM. Orlando, M. Orlando Laboratorio di Biochimica Clinica Istituto Superiore di Sanità Viale Regina Elena 299 00161 Roma, Italy Tel.: (+390) 6-4990-3398 Fax: (+390) 6-4938-7137 E-mail:morlando@iss.itLaboratorio di Biochimica Clinica, Istituto Superiore di Sanità, RomaSearch for more papers by this author First published: 07 July 2008 https://doi.org/10.1046/j.1423-0410.2001.00018.xCitations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume80, Issue2February 2001Pages 121-121 RelatedInformation

Laboratories performing analyses in the field of occupational and environmental medicine (OELM) must provide reliable results for an increasing number of analytes related to exposure to chemicals. Participation in external quality assessment schemes (EQAS) allows laboratories to assess their performance and is regarded as a pre-requisite for accreditation from appropriate national and supranational bodies. Within the framework of the European Union, harmonisation of procedures for evaluation of laboratory performance in EQAS is desirable, in order to achieve a similar degree of excellence within Europe. Collaboration among different countries would also be profitable to compare experiences, develop new schemes, covering a wider range of analytes, and to devise common research on specific problems. We report on initiatives developed to meet this objective, in collaboration with the Standards, Measurements & Testing (SM&T) programme of the European Commission (EC), Directorate General XII. Meetings were held in Dublin and Rome which allowed experience among European EQAS organisers in OELM to be shared. Discussion focused on the identification of common needs and areas where collaborative work could be carried out.

The benefits and drawbacks consequent to the widespread use of chemicals are inextricably interwoven. According to recent estimates, more than 8 million substances are presently known, 70,000 of which are in common use as industrial compounds, pesticides, Pharmaceuticals, food additives, cosmetics and the like. It is estimated that substances used as such will increase annually by 1000 in number. The deleterious consequences deriving from their exploitation pose tremendous challenges to the scientific community for the protection of human health and the environment. Therefore it is of utmost priority to appropriately select valid information generated in this investigation area and to convey it correctly to users. Here, the adoption of the principles of good laboratory practice in experimental activities is essential, as well as the creation of global networks for data exchange on the safe use of chemicals. The structure and goals of the International Register of Potentially Toxic Chemicals (IRPTC, the database of the United Nations Environment Programme) are detailed to give an example of such an undertaking. Seventeen fields are covered,i.e. identifiers, properties and classification, production/trade, production processes, use, pathways into the environment, concentrations, environmental fate tests, environmental fate, chemobiokinetics, mammalian toxicity, special toxicity studies, effects on organisms in the environment, sampling/preparation/analysis, spills, treatment of poisoning, waste management and recommendations/legal mechanisms.

Between 1992 and 1994, a new screening campaign for blood Pb monitoring in the Italian general population was carried out. Since the first campaign (started in 1978, in accomplishment of the European Community Directive 77/312/EEC) a working group of the Laboratory of Clinical Biochemistry at the Italian National Institute of Health (Istituto Superiore di Sanità), as the Reference Centre (RC), has coordinated the activity of various laboratories spread over the national territory. Appropriate quality assurance procedures, including an external quality assessment scheme (EQAS), were elaborated. Within the EQAS, three or four trials were carried out every year. Each laboratory participating in the trial analyzed eight control samples prepared from cow blood at different Pb concentrations. The results obtained by each peripheral laboratory and the RC between 1992 and 1994 have been compared by regression analysis. The same statistical method was adopted to compare the results obtained by each peripheral laboratory and the RC in the duplicate analysis of about 10 per cent of the human samples collected during the 1992–1994 monitoring campaign. There was no evidence of systematic differences between the regression lines obtained on control and human samples. In spite of the lower Pb concentration in the control samples analyzed during the 1992–1994 campaign, the analytical performance of the laboratories was better than that obtained in the previous screening campaign (1985–1986). Blood Pb levels observed in human samples collected between 1992 and 1994, confirm the downward time trend observed in the campaigns carried out in 1978–1979, 1980–1981 and 1985–1986. This study confirms that the results obtained in an EQAS are representative of the actual performance in the analysis of real (human) samples.