Simultaneous determination of free fluoride and monofluorophosphate in toothpaste by capillary electrophoresis with capacitively coupled contactless conductivity detection.
Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4)D) was used for rapid, accurate and simultaneous determination of free fluoride and monofluorophosphate (MFP) in six different toothpaste samples. A buffer solution containing 15 mmol L(-1) histine, 25 mmol L(-1) lactic acid, and 2.5 mmol L(-1) tetradecyltrimethylammonium bromide (TTAB) was used as background electrolyte (BGE). A complete separation of the analytes and the internal standard (tartrate) could be attained in less than 2.5 min. The limits of detection (LOD) and quantification (LOQ) were, respectively, 0.17 and 0.57 mg L(-1) for free fluoride and 0.70 and 2.33 mg L(-1) for MFP. Recoveries ranging from 85 to 107% were obtained for samples spiked with standard solutions of free fluoride or MFP. The CE-C(4)D method was compared to an ion-selective electrode (ISE) method and the results were in good agreement. More importantly, the CE-C(4)D method demonstrates the advantage of being able to determine MFP without a prior hydrolysis step.
Institute of Chemistry, University of Campinas, Campinas 13083-970, SP, Brazil.
Ivanilce Cristina
IC
Guimarães
Camila Cardoso
CC
Rezende
José Alberto
JA
Fracassi da Silva
Dosil
D
Pereira de Jesus
D002021:Buffers; D004553:Electric Conductivity; D019075:Electrophoresis, Capillary / Q000379:methods*; D005459:Fluorides / Q000032:analysis*; D010710:Phosphates / Q000032:analysis*; D012015:Reference Standards; D014100:Toothpastes / Q000032:analysis*
D002021:Buffers; D010710:Phosphates; D014100:Toothpastes; C012980:fluorophosphate; D005459:Fluorides