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This report discusses the eighth intercomparison exercise sine 1989 of a project which connects laboratories working in different areas. The results are presented here are those of the 1996 exercise.
Artificial rainwater samples, with concentrations close to the values ordinarily measured in northern Italy, and a solution of sodium hydrogen carbonate stabilised with chloroform, were prepared in September 1995 by the Environmental Institute of the JRC Ispra, and the results elaborated jointly with the C.N.R Istituto Italiano di Idrobiologia, Pallanza. Homogeneity and stability tests were performed to check the reliability of the samples. Results showed that pH, alkalinity, calcium, sodium and potassium were the variables showing the highest degree of error. Most of the variables examined showed a prevalence of systematic over random errors. pH and alkalinity were among the most critical measurements and the results stress the need for strict measurement protocols to improve the comparability between the different laboratories. Some analytical techniques (eg the use of colour indicators in the case of alkalinity and turbidimetry for sulphate) proved to be quite inadequate for measuring low concentrations.
The differences in the concentrations of anion and cations, and the comparison of measured and calculated conductivity, are an indication that some laboratories are not checking their results using the methods suggested in the previous exercises.

Additional information

Authors: MOSELLO R ET AL, Istituto Italiano di Idrobiologia, CNR, Verbania Pallanza (IT);BIANCHI M ET AL, JRC Ispra (IT)
Bibliographic Reference: EUR 17673 EN (1997) 47pp., FS, free of charge
Availability: Available from the Public Relations and Publications Unit, JRC Ispra, I-21020 Ispra (IT), Fax: +39-332-785818
Record Number: 199711135 / Last updated on: 1997-09-16
Original language: en
Available languages: en