(144c) In-Situ Analysis of Organics In Exhaled Breath Utilizing Acid Catalyst Membranes

Measurement of acetone content in human breath has been suggested as a non-invasive method to the diagnosis of diabetes and/or ketoacidosis.  Existing methods use time consuming, ex-situ analyses of breath condensate that limit broad, real-time application.  In the present study, the diffusion and immobilization of chemically and optically active probe molecules into the heterogeneous domains of perfluorosulfonic acid (PSA) polymer membranes is investigated for direct, one-step gas phase acetone analysis utilizing a hand-held device.  The membranes act as acid catalysts for the condensation reaction of acetone and the immobilized agents at temperatures above the acetone boiling point, yielding an optical response in the visible region of the electromagnetic spectrum that may be observed utilizing standard light emitting diodes (LED’s). Partitioning of the immobilized concentration among the lipophilic, hydrophilic, and transitional domains within the PSA membrane is shown to control the sensitivity of the membrane to acetone exposure.  The detection limit of this method is found to be less than 1 ppb and is thus comparable to that of more typical, but ex-situ GC/MS and HPLC analyses.  Using this method, it is possible to observe the real-time exhaled acetone concentrations of diabetic and non-diabetic patients during periods of fasting as a means to correlate breath acetone levels to blood glucose concentrations and the extent of ketoacidosis in diabetic patients.  Extensions of this approach to other organic molecules that can be used as biomarkers of human health in exhaled breath are discussed for the development of multi-sensor arrays capable of real-time medical diagnostics and environmental monitoring.