Influence Factors on Particle Growth for On-line Aerosol Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

An evaporation/condensation flow cell was developed and interfaced with the matrix-assistedlaser desorption/ionization (MALDI) time-of-flight mass spectrometer for on-line bioaerosoldetection and characterization, which allows matrix addition by condensation onto the laboratory-generated bioaerosol particles. The final coated particle exiting from the con-denser is then introduced into the aerodynamic particle sizer spectrometer or home-built aerosol laser time-of-flight mass spectrometer, and its aerodynamic size directly effects on the matrix-to-analyte molar ratio, which is very important for MALDI technique. In order to observe the protonated analyte molecular ion, and then determine the classification of bi-ological aerosols, the matrix-to-analyte molar ratio must be appropriate. Four experimental parameters, including the temperature of the heated reservoir, the initial particle size, its number concentration, and the matrix material, were tested experimentally to analyze their influences on the final particle size. This technique represents an on-line system of detec-tion that has the potential to provide rapid and reliable identification of airborne biological aerosols.