Evaluation of a micro-fabricated pyrolyzer for the detection of Bacillus anthracis spores

A micro-fabricated device for pyrolysis (i.e. micro-pyrolyzer) has been evaluated for pyrolysis and thermal hydrolysis methylation using Bacillus anthracis spores. The micro-pyrolyzer consists of a silicon wafer substrate with either a circular (2.7 mm diameter) or square (6.25 mm(2) area) silicon-nitride membrane heated by a platinum resistive element. A metal housing (i.e. test fixture) encloses the micro-pyrolyzer and serves as a manifold for the air carrier gas. The test fixture was interfaced to a quadrupole ion trap mass spectrometer via a direct capillary (100 mum x 1.4 m). The 360-440degreesC pyrolysis of B. anthracis spores produced dipicolinic acid (DPA) similar to that from a furnace pyrolyzer. In further studies, B. anthracis spores subjected to thermal hydrolysis methylation conditions produced ions characteristic of dipicolinic acid dimethyl ester. Results demonstrate the micro-pyrolyzer devices are capable of temperatures and heating rates to perform pyrolysis and thermal hydrolysis methylation. (C) 2004 Elsevier B.V. All rights reserved.