Elemental composition of nanoparticles with the nano aerosol mass spectrometer.
The nano aerosol mass spectrometer (NAMS) irradiates individual, size selected nanoparticles with a high energy laser pulse to generate a mass spectrum consisting of multiply charged atomic ions. The elemental composition of the particle is determined from the ion signal intensities of each element, which requires deconvoluting isobaric ion signals at 4 m/z (O(4+) and C(3+)) and at 8 m/z (O(2+) and S(4+)). A method to deconvolute these ion signals using sucrose and ammonium sulfate as calibrants is presented. The approach is based on the assumption that the charge state distribution of a given element is independent of the chemical form of that element in the particle. Relative to previously reported methodology, the new approach permits accurate and precise determination of sulfur, which is crucial for interpretation of ambient nanoparticle data sets. With this approach, the differences between expected and measured elemental ratios of C, O, N, and S for a variety of test particles were generally much less than 10%, although a difference as high as 16% was observed.
Zordan
Christopher A
CA
Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
Pennington
M Ross
MR
Johnston
Murray V
MV
D000336:Aerosols / Q000737:chemistry*; D000645:Ammonium Sulfate / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry
D000336:Aerosols; D013395:Sucrose; D013455:Sulfur; D002244:Carbon; D009584:Nitrogen; D010100:Oxygen; D000645:Ammonium Sulfate