Trends in intercomparisons 8701 - 9812: pH, cond, NO3 + NO2, Cl, SO4, Ca, Mg, Na K and aluminium (ICP Waters report 56/2000)

Abstract

Intercomparison tests connected to the International Cooperative Programme for Monitoring and Assessment of Acidfication of Rivers and Lakes, have been organizsed every year since 1987 by the Programme Centre at Norwegian Institute for Water Research. Sixteen laboratories have participated in six more intercomparisons. These laboratories were selected for evaluation of possible trends in their performance based on the intercomparison results reported. No clear performance trend for this group of laboratories can be found. A probable reason for this may be that nearly all of these laboratories have been well established for many years, and thus the participation in intercomparisons will have only minor effects on their analytical quality. However, some laboratories show systematically positive or negative deviations from the target value, and should improve the methods used. Others show random deviations from the target value and should improve the internal control routines. During the twelve year period acceptable results have been reported for conductivity from 8 laboratories, nitrate + nitrite from 3, chloride from 6, sulfate from 8, calcium from 10, magnesium from 11, sodium from 2, and potassium from 4 laboratories.