Microextração em fase sólida em cromatografia gasosa para detecção de ácidos orgânicos em água residuária de fecularia.

Abstract

Manipueira is generated in the process of making flour by pressing the grated cassava, resulting in a liquid residue which has a composition rich in nutrients and a high level of pollutant substances, so there are proposals based on research by several authors, with the goal to add value to manipueira as a byproduct in order to reduce environmental pollution. The growing demand for environmental safety elevates the importance of this analysis in order to provide the use of such waste. As a result, there is an increase in the need for analysts to develop fast, reliable and accurate methods. The solid phase microextraction (SPME) is a technical evolution, which reduces the sample preparation and therefore reduces the time of analysis and solvent extraction. There are few reports in the literature using this technique in the analysis of volatile organic acids and detection and quantification of organic acids in cassava, and it may be a promising technique for low generation of organic waste in the analysis, since there is no use of solvents in the extraction and in the chromatographic method. The anaerobic digestion process occurs in manipueira, in which there is the formation of volatile acids such as acetic, propionic, butyric. The objective of this study is to implement a method of analysis in a gas chromatograph using SPME Solid Phase Microextraction to detect and quantify organic acids in manipueira. To optimize the conditions of the method, the DCCR 23 experimental design was used, with the factors of exposure time of the fiber, NaCl concentration and heating, which contributed to determine the best conditions of the method. The factors that most influenced the determining recovery of the acids: acetic acid the time of exposure of the fiber and the concentration of NaCl; propionic acid concentration of NaCl and heating; and butyric acid heating and NaCl concentration. The desirability technique allowed the simultaneous evaluation of responses and the optimal conditions for the method. The process presented overall desirability of 91.86% and levels of the factors defined in the following condition: exposure time of the fiber of 23.24 minutes, NaCl concentration to 40% and heating of the solution equal to 65 °C.