Abstract
A relationship between color fading and decrease of disinfectant activity of Povidone-Iodine (PVP-I) gargle was examined.
A linear correlation between the absorbance at 550 nm and the concentration of free iodine (I2) was confirmed. Furthermore, a good correlation was observed between the bactericidal activity and the concentration of the free I2, though only within the narrow range, 0.063-0.148 mg/ml of free I2 concentrations.
The PVP-I gargle containing free I2 at the concentration of 0.131 mg/ml exhibited sufficient bactericidal activity in vitro, nevertheless it was a colorless liquid to the naked eyes.
These results suggest that whether or not the disinfectant activity of PVP-I gargle still remains in the proper solution should be estimated on the basis of the exact concentration of free I2, not on the basis of a degree of the browrlish color of the solution.
