FT-ICR analysis of urban air particulates: Problems with SRM 1649

We used the National Institute of Standards and Technology Standard Reference Material (SRM) 1649 as the particulate source for development of a screening procedure for nonvolatile and semivolatile organic chemicals In urban air particulates. Negative Ion laser desorption/ionization Fourler transform ion cyclotron resonance mass spectrometry (LD FT-ICR MS) was the method applied to these particulates. Polynuclear aromatic hydrocarbon (PAH) oxygen derivatives were identified In addition to the more abundant underivatized PAHs. The contaminant, dichlorophene (1, C13H10O2Cl2) was present in the samples at approximately 1.6 parts-per-thousand. This compound and its reaction products were present in samples even after extraction and acid/base fractionation. The contaminant and its reaction products, present significant interferences for the use of negative ion detection for screening these samples for trace and ultra-trace levels of electron capturing materials. Since the contaminant is present at higher levels than any other organic compound in the matrix, it may also be an interference for positive ion analysis. The utility of SRM-1649 for the development and certification of screening procedures for atmospheric contaminants is vitiated by the fungicide contamination.