An inter-laboratory comparative study of fluoride determination in water
South Africa is on the brink of implementation of mandatory fluoridation of municipal water following the final approval by Parliament in 2001. The ability to accurately measure fluoride in water is an obvious prerequisite for the safe and effective implementation of water fluoridation. This paper evaluates the current status of fluoride determination in water in South Africa. The study was undertaken by the University of Johannesburg in collaboration with the South African Bureau of Standards as part of their ongoing Water-Check Programme. River water, borehole water, and synthetic water samples were sent to 66 participating laboratories in South Africa in March 2004. The results obtained from the analysis of 7 fluoride-containing samples with varying matrix composition, show that 50% of the laboratories could achieve results that fall between a lower limit of -20% and an upper limit of +20% relative to the true value. The precision (%RSD) for the determination of samples with fluoride concentration at the important level below 0.5 mg/ℓ was poor, ranging from ±20% at 0.5 mg/ℓ to ±100% at 0.1 mg/ℓ. The two major analytical techniques used by the participating South African laboratories were ISE (40%) and IC (36%)..
Water SA Vol.32 (3) 2006: pp.365-370