Potentiometric measurement of ionic, acid-labile and covalently bound fluorine

Fluoride (F−) is the predominant chemical form of F in serum and bone, during administration of NaF as cariostatic agent or in the treatment of osteoporosis. In the treatment with sodium monofluorophosphate (MFP), F−, F bound to proteins by acid-labile linkage and non-volatile covalently bound F are detected. Only F− is detectable with the ion-selective electrode. This paper describes a method for the measurement of non-volatile covalently bound F with the ion-selective electrode, which has a detection limit of 0.8 ± 0.6 nmol, within-run standard deviation of 7 nmol and a between-run standard deviation of 13 nmol at 100 nmol F and has a linear behaviour above 1 nmol. This paper also reports a methodology for the potentiometric measurement of F−, acid-labile F and covalently bound F in biological samples.