Laboratory Performance Evaluation in Terms of Water Analysis Through an External Quality Control

Abstract

This paper presents the results of participation of Institut National des Sciences et Techniques Nucléaires-Madagascar (INSTN-Madagascar) in interlaboratory comparisons organized annually, since 2007, by Southern African Development Community WaterLab Association. The following text describes an overview of the utility of provided proficiency testing programs used as an external quality control with respect to proving consistency and reliability of water analysis at INSTN-Madagascar. Total reflection X-Ray Fluorescence spectrometry and Atomic Absorption Spectrometry are both used to measure the following trace metals: Al, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Cd, Pb. The analysis of minor and major ions such as Cl–, F–, NO3–, SO42–, PO43–, K+, Na+, Ca2+, Mg2+ are conducted by using Ion Chromatography. To illustrate, graphical distributions of z-scores calculated from the results of water measurements are presented. During the consecutive proficiency testing rounds, INSTN-Madagascar has succeeded to have more than 80% of the values within tolerance limits on 2007, 2008, 2010, 2011, 2012 and 2013. This paper shows some of the considerations for participating to proficiency testing exercises which could be used to obtain certain value from the schemes.