No abstract

Exhaled breath acetone (EBA) is gaining relevance as an alternative noninvasive biomarker of diseases like diabetes and, more recently, also of heart failure (HF), thanks to contributions of joint work of researchers from IQ-USP and INCOR-FM-USP. This dissertation is about improvements that have been made in the spectrophotometric method of acetone determination aiming to speed up and improve the reliability of the methodology for EBA analysis that is routinely used in the IQ/INCOR collaboration. The method is based on the reaction between acetone and salicylaldehyde in strong alkaline medium. All activities have been developed in order to get results quickly and reliably. First of all, the determination wavelength has been revised. In order to do that, some UV/Vis absorption spectra of the colored reagent and product were recorded, at many acetone concentrations, for some conditions (such as light exposure or not, variations of reagent/acetone solution proportion and heating vials containing reactive medium). After that, slope of analytical curve, intercept and slope/intercept quotient were plotted as a function of wavelength. Posteriorly, reaction kinetics were tested, also in some conditions (such as heating in many temperatures, variations of reagent/acetone solution proportion and extra addition of sodium hydroxide) in order to reduce determination time. Finally, after being defined some aspects of the procedure to be changed, that changes were applied to the determination of acetone in some real samples, collected by coworkers in the hospital.