Aguas

Trends in Analytical Chemistry, Vol. 29, No. 5, 2010

Trends

Standard gas mixtures – indispensable reference materials in the analysis of gaseous media
´ ´ Marta Słominska, Piotr Konieczka, Jacek Namiesnik
In recent years the need for the quality control and assurance of analytical measurement results has been particularly strongly emphasised. Certified reference materials play aninvaluable role in this process. The article characterises the basic types of reference materials, focusing in particular on those in the gaseous state. It also reviews the literature on the techniques of preparing standard gas mixtures over the last ten years (1999–2009) and highlights the main developments in this field. ª 2010 Elsevier Ltd. All rights reserved.
Keywords: Certified reference material;Dynamic technique; Gas; Gaseous reference material; Laboratory reference material; Mixed technique; Reference material; Standard gas mixture; Static technique; Thermal desorption

1. Introduction
´ska*, Marta Słomin Piotr Konieczka, ´ Jacek Namiesnik ´ Gdansk University of Technology, Chemical Faculty, Department of Analytical Chemistry, ul. G. Narutowicza 11/12, ´ 80-233 Gdansk, Poland

*Corresponding author; E-mail: korpala.m@poczta.onet.pl

The need to ensure an appropriate quality of life for living organisms on every plane of their existence means that quality assurance of analytical results is becoming a matter of increasing significance. The reliability of the information supplied by measurements of physical and chemical properties of materials analysed is important not onlyfor industry and technological development: conservation of the environment, the proper management of its resources and the evaluation of environmental hazards also depend on the quality of analytical measurements. In order to carry out tasks in this field, and to control and to assure the quality of the results of analytical measurement, two basic tools are required:  appropriate analyticalprocedures; and,  control devices and measurement equipment. The analyst uses these tools to investigate representative samples in order to

acquire measurement data, which, in turn, constitute the foundation of reliable analytical information. But to make sure that this information is indeed reliable, a further step is necessary, and it involves:  calibration of measurement instruments; and, validation of analytical procedures. In connection with these processes, it is essential to have suitable materials with properly understood characteristics and composition. The analysis of such materials is thus an integral aspect of procedures in all known systems of quality assurance and control (QA/QC) of the results of analytical measurement. Increasingly, there is a need to know the chemicalcomposition of and the processes taking place in such gaseous media as:  atmospheric air;  air at the workplace;  indoor air;  technological gases;  air in agricultural livestock operations;  the air exhaled by human beings; and,  biogenic gases (e.g., due to volcanic activity). Increasing interest is being shown in analytical methodologies suitable for determining various types ofcomponents in samples of such gases [1]. It goes without saying that our focus is on the determination of trace and ultra-trace components – hence, the intensive search for novel analytical methods that will make environmental monitoring and

0165-9936/$ - see front matter ª 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.trac.2010.02.003

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Trends in Analytical Chemistry, Vol.29, No. 5, 2010

Table 1. Characteristics of the main contaminants of gaseous media [2–5] Air pollution SO2 – sulphur dioxide NOx – nitric oxides Characteristics - main source: combustion of mineral fuels, fuel industry - volcanic eruptions – a natural source of sulphur dioxide - produced during combustion processes, particularly at high temperatures - nitric oxides in combination with volatile...