Optimization of quartz tube pyrolysis atmospheric pressure ionization mass spectrometry for the generation of bacterial biomarkers

Abstract

Experimental procedures were investigated to improve the efflux of biomolecule pyrolyzates from quartz tube pyrolysis under atmospheric pressure ionization mass spectrometry conditions. Heating regimes, airflows, and ion focusing parameters were optimized to increase the informative mass spectral signals generated from the pyrolysis of Gram-positive bacterial spores and vegetative cells. Dipicolinic acid (DPA) is found in 5-15% by weight in Gram-positive Bacillus spores, and the parameter optimization procedures provided an intense mass spectral signature of the m/z 168 protonated DPA molecule with a minimization of pyrolytic and ionization fragments. Moreover, mass spectral information from the optimization protocols yielded peaks and mass patterns characteristic of DNA and RNA nitrogen bases, protein diketopiperazines, and amino sugars.

Recent Advances in Real-time Mass Spectrometry Detection of Bacteria

“…This compound makes up 5-15 % of a Bacillus spore, and as such it is representative for the possible presence of Bacillus anthracis. Specific pyMS based methods for detecting Bacillus through DPA were developed (Beverly et al 1996;Goodacre et al 2000;Tripathi, Maswadeh, and Snyder 2001). Tandem mass spectrometry was employed to show that a more general characteristic of bacteria, their fatty acid profile, is accessible by pyMS/MS without prior chromatographic separation (DeLuca et al 1990).…”

“…Tandem mass spectrometry was employed to show that a more general characteristic of bacteria, their fatty acid profile, is accessible by pyMS/MS without prior chromatographic separation (DeLuca et al 1990). A fast in situ chemical methylation reaction, to form fatty acid methyl esters (FAMEs), is included to allow better volatilization (Basile et al 1998;Barshick, Wolf, and Vass 1999;Tripathi, Maswadeh, and Snyder 2001;Poerschmann et al 2005). Although FAME profiling does not provide a complete typing scheme for bacteria, correlation with laboratory profiles can be employed in detection applications.…”

Quantitative assessment and optimization of parameters for pyrolysis of bacteria with gas chromatographic analysis

“…Despite this experience, there is surprisingly little information available in the open literature on the quantitative influence of individual parameters on results from Py-GC characterization of intact bacteria. The effects of some parameters have been explored in limited manner for different types of pyrolysis units or different types of samples [3,13,14,[16][17][18]; however, quantitative repeatability for Py-GC analysis of bacteria was needed in our laboratory along with an understanding of the analytical significance of experimental variables. Some of these parameters include the time of pyrolysis, the temperature of pyrolysis, the gas atmosphere, gas flow, and chromatographic conditions such as initial temperature of the column and the rate of temperature programming, the pyrolyzer design and geometry, the sample amount and depth of sample on the pyrolysis ribbon.…”

Perspective on Improving Environmental Monitoring of Biothreats

“…Furthermore, the data observed in many peer-reviewed efforts use simple mixtures or even pure samples of target organisms, which do not reflect the real-life situations where samples contain hundreds of organisms and diverse biological materials. The MS techniques that have been investigated include pyrolysis MS (Tripathi et al, 2001 ; Wilkes et al, 2006 ), pyrolysis-derivatization MS/MS (Griest et al, 2001 ), derivatization gas chromatography GC-MS (Jeong et al, 2014 ), aerosol laser ablation (LA) MS (Fergenson et al, 2004 ), and aerosol matrix assisted laser desorption/ionization (MALDI) MS (Jung et al, 2014 ). The high cost, generally large footprint, and power requirements (mostly because of vacuum pumps) are factors that have limited the application of MS in autonomous detection devices.…”