Accreditation and Quality Assurance

, Volume 19, Issue 4, pp 259–268 | Cite as

Proficiency test of pH, conductivity and dissolved oxygen concentration field measurements in river water

  • Teemu Näykki
  • Mirja Leivuori
  • Katarina Björklöf
  • Ritva Väisänen
  • Marko Laine
  • Tero Väisänen
  • Ivo Leito
Practitioner's Report


In 2013, Proftest SYKE organised the first proficiency test (PT) in Finland for field measurements of temperature, conductivity, dissolved oxygen concentration, oxygen saturation and pH value in river water. The aim was to pilot the organisation of an in situ proficiency test—particularly, how to select the test location—and how to assess the homogeneity and stability of the measurement site and the water to be tested. The focus was also to evaluate the suitability of the common field sensors used for water analysis, as well as the comparability of the results between the instruments under field conditions. The overall application of quality assurance procedures was also surveyed. This paper deals with the results, findings and recommendations for the measurement of pH, conductivity and dissolved oxygen concentration. In total, nine participants with 16 sensors took part in the proficiency test. For the evaluation of the performance of each participant, z scores were calculated allowing 3 % to 8 % deviation from the assigned value. The standard deviation of the participant’s results was lower than organiser expected, and 80 % of the results for pH, 79 % for conductivity and 69 % for dissolved oxygen concentration were regarded as satisfactory. According to the results, the most challenging measurement was for dissolved oxygen with a Clark cell-type measurement principle based on electrochemical reaction. All sensors tested in the PT were less than 5 years, old and they were calibrated according to the manufacturer’s instructions. None of the participants had estimated measurement uncertainty for their sensor measurements. In addition, internal and external quality assurance protocols were usually lacking.


Proficiency test pH Conductivity Dissolved oxygen Sensor Field measurement In situ 



The authors would like to thank Jaana Marttila and Maija Lehtinen from Uusimaa ELY Centre (Centre for Economic Development, Transport and the Environment) and Heli Vahtera from the Water Protection Association of the River Vantaa and Helsinki Region for assisting in the selection of the site for the PT. Mikko Junttila is acknowledged for his validation of the sensors. This work has been partially supported by Graduate School “Functional materials and technologies” receiving funding from the European Social Fund under project 1.2.0401.09-0079 in University of Tartu, Estonia.

Supplementary material

769_2014_1064_MOESM1_ESM.pdf (667 kb)
Supplementary material 1 (PDF 666 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Teemu Näykki
    • 1
  • Mirja Leivuori
    • 2
  • Katarina Björklöf
    • 2
  • Ritva Väisänen
    • 2
  • Marko Laine
    • 3
  • Tero Väisänen
    • 4
  • Ivo Leito
    • 5
  1. 1.Environmental Measurement and Testing LaboratoryFinnish Environment Institute (SYKE)HelsinkiFinland
  2. 2.Reference LaboratoryFinnish Environment Institute (SYKE)HelsinkiFinland
  3. 3.Finnish Meteorological InstituteHelsinkiFinland
  4. 4.Environmental Measurement and Testing LaboratoryFinnish Environment Institute (SYKE)OuluFinland
  5. 5.Institute of ChemistryUniversity of TartuTartuEstonia

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