title: Rapid monitoring of fluoride (F-) levels in blood plasma.
abstract: Evidence exists that plasma F- concentrations of 1.0 part/10(6) are nephrotoxic and that much lower levels disturb enamel mineralization. Ingested F(-)-containing gels, tablets and toothpastes all raise plasma F- levels significantly, as does prolonged exposure to fluorine-containing anaesthetic gases. There is, therefore, a continuing need to determine the total F- burden accruing in any given individual from multiple sources, as well as the average plasma F- burden which could be carried without risk to kidneys or teeth. To meet this need by facilitating fast and accurate monitoring of plasma F- levels, a new method has been devised and tested. A specific ion F- electrode in conjunction with a combination pH electrode forms a differential cell very sensitive to low concentrations of F-. When compared with the performance of a single F- electrode plus Ag/AgCl reference electrode, the differential cell is not only as consistent and accurate but also has a much shorter response time (2 vs. 20 min) and requires a much smaller sample volume (0.05 vs. 1.0 ml). In healthy subjects the mean plasma F- level was 0.044 (+/- 0.001) parts/10(6); in three patients undergoing prolonged (24 h) sedation with the fluorine-containing gas isoflurane, mean plasma F- rose to 0.275 (+/- 0.025) parts/10(6). No binding of F- to plasma components occurred at the operating pH (1.2) of the differential cell and plasma could be stored for at least 40 days at low temperature (4 degrees C) without alteration to measured F- values.
authors.affiliation: Department of Anaesthesia, Bristol Royal Infirmary, UK.
authors.forename: J E
authors.initials: JE
authors.lastname: Tyler
authors.forename: D F
authors.initials: DF
authors.lastname: Poole
authors.forename: K L
authors.initials: KL
authors.lastname: Kong
mesh_terms: D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D005459:Fluorides / Q000097:blood*; D006801:Humans
chemical_list: D005459:Fluorides