1 research outputs found
Water-Resistant Polymeric Acid Membrane Catalyst for Acetone Detection in the Exhaled Breath of Diabetics
Endogenous
volatile organic compounds (VOCs) such as acetone in
exhaled human breath are associated with metabolic conditions in the
bloodstream. Development of compact, rapid detectors of exhaled breath
chemical composition in clinical settings is challenging due to the
small sample size that can be collected during a single exhalation
as well as spectroscopic interference by the abundance of water. In
this paper, we show that the activity of a catalytic polymer membrane
(Nafion 117) toward the heterogeneous condensation reaction of immobilized
resorcinol reagent with gas-phase acetone can be preserved even at
100% ambient relative humidity through the incorporation of organic
acids such as vanillic or tiglic. The reaction produces a colored
flavan product that permits highly selective and sensitive correlation
to acetone concentration in exhaled breath. Such behavior suggests
solvent displacement, analogous to homogeneous liquid-phase systems.
However, unlike classic acid–base equilibria, the extent of
optode water resistance is shown to increase with the p<i>K</i><sub>a</sub> of the imbibed organic acid while peak signal intensity
of the imbibed acid undergoes a bathochromic shift to longer wavelengths.
These observations are consistent with competition between organic
acid deprotonation by water in a mixed solvent system on the one hand
and immobilization on the other. Finally, we demonstrate how when
applied to the direct chemical analysis of acetone in exhaled human
breath, the approach yields excellent correlation to blood glucose
in diabetics