Study On Determination Of Activated Oxygen In The Whitening Toothpaste And Its Stability

Determination of the activated oxygen in the peroxide-containing whitening toothpaste are studied in this thesis, including the KMnO4 method, the indirect iodine-containing method , the iodine-blue spectrophotometric method and its improved method. The experiment results show that the KMnO4 method can't be used in the complex toothpaste system, the indirect iodine-containing method is feasible in theory, but not in present lab condition, and it needs further study in the future. However, the iodine-blue spectrophotometric method, especially its improved method is proved practicable in the determination of the activated oxygen in the whitening toothpaste. And its optimum operation conditions are confirmed as follows: the maximum absorption wave length: 585nm; 200g/L NaCl: 7mL, 1.5mol/L HC1: 3.5mL, the acidifying time: 4 minutes, 10g/L KI: 3.5mL, 10 g/L Starch: 1.5 mL. Furthermore, Beer's law is obeyed over the range of 0-15 u g/25mL for hydrogen peroxide, and the equation is as follows: y = -0.01978 + 0.03649x; the differential: 0.01457; the relevant co efficient: 0.99773; the errors of two constants: 0.01012, 0.0011. And the improved iodine-blue spectrophotometric method is shown easy, quick and correct.Preliminary research on the factors which affect the stability of the peroxide-containing whitening toothpaste is done. It is proved that in a peculiar toothpaste, the extents of the effect by different components are as the following: glycerin (humectant), TiO2 (stabilizing agent), Methyl Peroxide (flavor), SiO2 (abrasive agent)% CaCO3 (abrasive agent), Sodium Lauryl Sulfate (surfactant agent). Moreover, the method on strengthening the stability of the whitening toothpaste is pointed out in this thesis.