Ácido glioxílico à formaldeído: degradação do ácido glioxílico em escovas progressivas por espectrofotometria e análise térmica.

Abstract

The hair plays an important role in the self-perception of human beings. In view of this, the cosmetics industry has revolutionized the Brazilian market by launching various products to beautify and treat the hair. There are several methods available in the market using these products, and one of them is the progressive brush. Some products have used this procedure substances that cause health risks, such as formaldehyde. Since ANVISA limited the use of this substance just 0.2%, many companies are replacing formaldehyde by glyoxylic acid. However, glyoxylic acid when applied to the hair and subjected to heat treatment releases formaldehyde, being dangerous and causing health risks. This work aimed to evaluate the degradation of glyoxylic acid in progressive brushes. Three different brands of commercial formulations (A1 and A2 containing glyoxylic acid the A3 containing and formaldehyde), which were analyzed by visible spectrophotometry, based on the reaction between formaldehyde and chromotropic acid in the presence of magnesium sulfate and was analyzed by thermal analysis techniques TG / DTG and DTA. The results showed that methods were able to identify and quantify the presence of formaldehyde in hair straightening products from the degradation of glyoxylic acid. The samples A1, A2 and A3 showed formaldehyde concentrations 0.05% (m/m), 0.03% (m/m) and 0.32% (m/m) respectively, in the spectrophotometric analysis. The thermogravimetric curves in thermal analysis identified 9% formaldehyde from pure glyoxylic acid and 6.51% in the progressive brush A1. Since procedures follow distinct patterns, it may explain the differences in percentages of formaldehyde found in the samples. According to the tests is confirmed degradation of glyoxylic acid in formaldehyde, enhancing the risks of using this type of cosmetic for hair straightening, it becomes as dangerous as using brushes with formaldehyde, whose toxicity is already thoroughly known.