Analytical performance characteristics of the separation of fluoride in toothpaste by capillary zone electrophoresis

The analytical performance characteristics of the separation by CZE of fluoride in toothpaste using a chromate-based electrolyte is discussed. Good precisions (n = 5) were recorded for absolute migration time (1.7% RSD), peak area (0.8% RSD) and peak height (0.4% RSD). Fluoride was separated in under 4 min without matrix interference or co-migration with phosphate (resolution ca. 8). The peak area calibration curve was linear between 5–120 g ml-1 of fluoride and using this curve, one toothpaste sample was determined to have about 12 g ml-1 (0.1% m/m undried basis) of fluoride. The limit of detection was 0.5 g ml-1 (3 × baseline noise) and the mean recovery was 106% (n = 10).