Fast spectrophotometric determination of fluoride in ground waters by flow injection using partial least-squares calibration

• Published in: Analytica chimica acta 2004-06, Vol.512 (1), p.157-163
• Main Authors: Arancibia, Juan A., Rullo, Anabel, Olivieri, Alejandro C., Nezio, Susana Di, Pistonesi, Marcelo, Lista, Adriana, Band, Beatriz S.Fernández
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Electrochemical methods; Exact sciences and technology; Flow injection analysis; Fluoride analysis; Ground waters; Partial least-squares regression; Spectrometric and optical methods; Sulphate interference
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2004.02.026

The presence of sulphate constitutes a serious interference in the usual zirconium lake-based spectrophotometric method for the determination of fluoride in water. In this report, full spectral data have been recorded for the zirconium lake of 2-(parasulfophenylazo)-1,8-dihydroxy-3,6-naphthalene-disulfonate (SPADNS) in the simultaneous presence of fluoride and sulphate, as obtained with a flow injection system with a diode-array detector. The information has been processed with partial least-squares (PLS) multivariate calibration. Adequate modeling using a sixteen-sample calibration set allows fluoride to be determined in ground waters by the automated flow injection method, even in the presence of sulphate in concentrations up to 1000 mg l −1. In the calibration range 0–1.50 mg l −1 for fluoride, the limit of detection is 0.1 mg l −1. The fluoride contents in real samples, as determined with the present method, were satisfactorily compared with those provided by ion selective potentiometry.