CE-MS: A useful tool for the identification of water-soluble polar organics in air and vehicular emitted particulate matter

Abstract

A CE-ESI/quadrupole-MS method using an ammonium acetate-based BGE (pH 4.7) was developed for the determination of isomeric benzoic acids in atmospheric aerosols and vehicular emission. UltraTrol™ LN was employed as the pre-coating polymer to suppress the EOF (0.3 × 10-9m2V-1 s-1) and achieve a baseline separation of the studied acids. Good repeatability for migration time (RSD<1%, N=10) was obtained without coating regeneration. The high pre-coating stability allowed coupling of CE to MS without ion suppression in the MS. In scanning mode and using field-amplified sample injection with electrokinetic injection (-5 kV for 60 s), LODs (S/N=3) ranged from 2.5 to 6 μg/L for standard target analytes prepared in DI water. In the presence of 100 mg/L of sulfate (added to simulate a sample matrix), LODs ranged from 8 to 90 μg/L. Several isomeric aromatic acids could be separated in atmospheric and diesel-engine-emitted particulate matter extracts based on their different acidities. Additional measurements with a flow infusion ESI Fourier transform ion cyclotron resonance MS were used for further structural information acquisition on the unknown compounds and allowed their formula to be proposed. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.