Determination of fluoride in drinking water and sea water by aluminium monofluoride molecular absorption spectrometry using an electrothermal graphite furnace

Abstract

A method is presented for the determination of trace levels of fluoride in drinking water and sea water, based on the formation of aluminium monofluoride in an electrothermal graphite furnace, followed by molecular absorption at 227.45 nm. Two linear intervals extending over wide F^– concentration ranges (0–0.2 and 0.2–0.4 µg ml^–1 for the peak-height relationship and 0–1 and 1–2 µg ml^–1 for the peak-area relationship) were found. The proposed method was applied to natural and artificial drinking and sea waters from a variety of sources and with different saline contents. The detection limit was 8 ng ml^–1 and the determination limit 20 ng ml^–1. The peak-height precision at 0.2 and 0.4 µg ml^–1 of F^– was 5% and 7%, respectively. F^– contents can be measured with a simple dilution. The use of a deuterium lamp allows simultaneous background correction. Interferences from cations, acidic media and anions were investigated.