Solid Phase Microextraction (SPME) as a Method to Defect the Presence of Escherichia Coli in Waster by Headspace Sampling and Gas Chromatography/Mass Spectrometry Analysis

A method was developed for detecting the metabolite indole produced by Escherichia coli in the headspace above a sample in Luria bertani broth. This method used solid phase microextraction (SPME) and gas chromatography/mass spectrometry to perform extraction and analysis. Five commercially available SPME fibers were investigated to determine the optimal fiber and extraction conditions. Polyacrylate (PA) and polydimethylsiloxane-divinylbenzene fiber coatings gave a statistically indistinguishable and best response compared to the other three types examined. The PA fiber coating was selected for further study. The lower level of detection was determined to be 1 colony forming unit (cfu) in 100 milliliters (mL) of water incubated for twelve hours at 37 degrees Celsius. Themethod detection level was determined to be 101-1000 cfu in 100 mL of water, although 11-100 cfu were detected 90.9% of the time. Forty water samples split, filtered and analyzed with SPME and membrane filtration were shown to be in agreement 57.1% more often than would be expected by chance (Kappa = 0.571, P<0.001). The results of this study showed significant promise in the use of SPME for detection of volatile metabolites of bacterial water contaminants. However, under the conditions optimized in this study, the method is neither sensitive nor fast enough to be considered superior over existing methods.