title: The rapid measurement of fluoride concentrations in stored human saliva by means of a differential electrode cell.
abstract: For the purpose of rapid measurement, the performance of a differential cell, consisting of a combination pH electrode and a F- electrode and used at low pH (1.2), was compared with the use of a single F- electrode at pH 5.0. The differential cell proved to be as accurate and consistent as the single electrode: its response time was 2 min for a saliva volume of 50 microliters; the response time of the single electrode was 20 min with a saliva volume of 1000 microliters. Analysis of salivary supernatant fluid provided an unreliable guide to the original salivary F- concentrations but if fresh whole saliva was acidified to pH 1.2 immediately upon collection, the original baseline values were repeatedly obtained when measurements were made at intervals over a storage period of 14 days at 4 degrees C. Immediate acidification thus provides a satisfactory method for collecting samples from separate populations and then transporting them at leisure to a laboratory for direct measurement at pH 1.2 with the differential cell.
authors.affiliation: MRC Dental Group, Dental School, Bristol, England.
authors.forename: J E
authors.initials: JE
authors.lastname: Tyler
authors.forename: D F
authors.initials: DF
authors.lastname: Poole
mesh_terms: D002118:Calcium / Q000032:analysis; D004566:Electrodes; D004867:Equipment Design; D005459:Fluorides / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012463:Saliva / Q000032:analysis*; D013048:Specimen Handling / Q000295:instrumentation / Q000379:methods
chemical_list: D005459:Fluorides; D002118:Calcium