Rapid Detection of Bacteria with Miniaturized Pyrolysis-Gas Chromatographic Analysis

摘要

Rapid detection and identification of bacteria and other pathogens is important for many civilian and military applications. The profiles of biological markers such as fatty acids can be used to characterize biological samples or to distinguish bacteria at the gram-type, genera, and even species level. Common methods for whole cell bacterial analysis are neither portable nor rapid, requiring lengthy, labor intensive sample preparation and bench-scale instrumentation. These methods chemically derivatize fatty acids to produce more volatile fatty acid methyl esters (FAMEs) that can be separated and analyzed by a gas chromatograph (GC)/mass spectrometer. More recent publications demonstrate decreased sample preparation time with in situ derivatization of whole bacterial samples using pyrolysis/derivatization. Ongoing development of miniaturized pyrolysis/GC instrumentation by this department capitalizes on Sandia advances in the field of microfabricated chemical analysis systems (μChemLab). Microdevices include rapidly heated stages capable of pyrolysis or sample concentration, gas chromatography columns, and surface acoustic wave (SAW) sensor arrays. We will present results demonstrating the capabilities of these devices towards fulfilling the goal of portable, rapid detection and early warning of the presence of pathogens in air or water. Results include successful pyrolysis/derivatization using only milliwatts of power and rapid (<5 minutes) separation of relevant FAMEs. We will also present data showing the effects of various derivatization schemes or air as carrier gas on GC performance. The capability of SAW sensor array detection of FAMEs and preliminary results on the differentiation of bacterial samples will also be discussed with respect to the goals stated above.