Comparison between the ion-specific electrode and SPADNS methods for analysis of fluoride concentration in the water supply

Abstract

The maintenance of adequate fluoride (F) concentration in the public water supply is fundamental for ensuring that the community use of F can reach the maximum benefit for caries control and minimum risk for dental fluorosis. Thus, surveillance systems must use accurate and valid analytical methods to determine F concentration and, according to the literature, give preference to the ion-specific electrode (F- ISE) analysis. Aim: The objective of this study was to compare the accuracy of the ISE and SPADNS methods in the determination of the F concentration in the same water sample. Methods: Duplicate water samples were taken from 30 sampling sites in the municipality of Maringá, state of Paraná, monthly for 12 months, totaling 276 samples. An aliquot was analyzed by the FOP-UNICAMP Oral Biochemistry laboratory, using the F- ISE method, and the other one, by the SANEPAR laboratory in Maringá/PR, using the SPADNS method. Descriptive analysis and Pearson’s correlation test were applied, with a significant level of p<0.05. Results: Results were expressed as ppm F (mg F/L), and a very strong positive correlation (r= 0.91; p<0.001) was detected between the two methods of analysis. Conclusion: Our findings suggest that the determination of f luoride concentration in water can be made with accuracy by the SPADNS method, a standardized analysis protocol.