Analysis of the concentration and pH of different brands and different times of sodium hypochlorite Análise da concentração e do ph de diferentes marcas comerciais e em diferentes tempos do hipoclorito de sódio

Abstract

The purpose of this study, in vitro, was to evaluate the concentration of free chlorine and pH Sodium hypochlorite solutions at different concentrations and time periods; and verify that they were within the specified by the manufacturer. Four samples Sodium hypochlorite solutions at different concentrations (4 to 6%, 2.5%, 5 to 7% and 2 to 2.5%) and presentations (commercial - Soda Clorada™, Uraby™, e Barra™, and manipulated - ISOFAR) were maintained without light and at roam temperature. The measurements took place in the opening of the bottles and at intervals of 7, 14, 21 and 28 days. The analysis of free chlorine content was performed by the method of iodometry and pH by a digital pH meter. It was found that the experimental time the marks ISOFAR and Uraby™, were to chlorine concentration lower than reported by the manufacturer and brands Soda Clorada™, and Barra™, above. Regarding the pH, the solutions tested showed a slight increase in values, followed by decrease. lt can be concluded that the solutions were not according to the specified concentration by the manufacturer; and there was a decrease of chlorine concentration and the pH ranged around 11 to 12.