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pH and electrolytic conductivity are important metrological quantities for several areas of industry. To get reliable results it is necessary to calibrate measuring instruments and devices regularly. For this purpose certified reference solutions are needed. DKD-K-06901 is a manufacturer of certified reference solutions and offers calibration services in the field of analytical chemistry. There are three accredited calibration procedures for the determination of pH used by ZKM - ANALYTIK - GmbH. A new calibration procedure for electrolytic conductivity was established by experts in DKD-K-06901 as the result of a development project in cooperation with National Metrology Institutes. The validation of all procedures is guaranteed by the participation in national and international comparison measurements. Furthermore DKD-K-06901 is actively involved in the work of technical and standardisation committees for developments of analytical quantities.

In today's economy goods and information are being exchanged globally, international travel is commonplace as is the cross-boarder transport of livestock and agricultural products, and this trend is set to continue. Just as important are issues that impinge on our quality of life, such as health care, the environment and food quality. A strong international measurement and standards infrastructure is critical to assure equity in trade and a high quality of life, by ensuring that products and services meet their specifications. In the field of chemical measurements, certified reference materials (CRMs), measurement standards and reference measurement results provide stated references upon which analytical laboratories can anchor their measurement results. The traceability of measurement results to internationally accepted stated references, together with their stated measurement uncertainties, as described in ISO/IEC 17025, provides the basis for their comparability and global acceptance. Recent global activities which are succeeding in developing a system for the international acceptance of chemical measurements are described, notably: activities of the National Metrology Institutes and the BIPM; the Mutual Recognition Arrangement of the International Committee of Weights and Measures (CIPM MRA) for National Calibration Certificates and Measurement Capabilities; the Inter-Laboratory Comparisons organised through the working groups of the Consultative Committee for Amount of Substance – Metrology in Chemistry (CCQM), and the activities of the Joint Committee for Traceability in Laboratory Medicine (JCTLM).

As part of a national quality assurance programme of the Cercl'Air in cooperation with the Swiss Federal Office for the Environment (FOEN) and the Swiss Federal Office of Metrology (METAS) there have been intercomparisons of air quality monitoring stations of interested institutions in regular intervals since 1988. The former approach, alternating between calibrations with test gases of measuring stations on site and gathering mobile measuring units for additional comparative measurements every second year, had to be modified as mobile measuring stations have become increasingly sparse over the last years. The idea was to find a solution to combine the two types of intercomparison in one campaign. The problem was solved by assembling a mobile reference station for measuring air pollution, with the addition of equipment to provide test gases for the candidate instruments. With this mobile measuring unit, calibration with test gases and comparative measurements could be performed on site at the candidate air pollution monitoring stations. The results of the 2007 intercomparison campaign showed that the achieved quality improvements in air pollution measurements over the last twenty years – decrease of expanded uncertainties in intercomparisons by a factor of 4 to 7 depending on the type of pollutant – could be sustained.

High-quality and long-term comparable time series of the relevant atmospheric observations are the essential prerequisite to understand the dynamical, physical and chemical state of the atmosphere from seasonal to multi-decadal time scales. For relevant gaseous compounds such as ozone, methane (CH4) and carbon monoxide (CO), the requirements are secured by tracing back these observations to common primary standards. Periodical audits of the system in operation and the performance of measurement sites provide additional information about data quality and comparability. The results of 48 audits conducted by the World Calibration Centre for Surface Ozone, Carbon Monoxide and Methane (WCC-Empa) at global stations of the Global Atmosphere Watch programme (GAW) from 1996 to 2009 show that most of the audited sites meet the data quality objectives for ozone and methane whereas the situation is less uniform for carbon monoxide.