Determination of 3,3 '-dichlorobenzidine and its degradation products in environmental samples with a small low-field Fourier transform ion cyclotronresonance mass spectrometer

3,3'-Dichlorobenzidine (DCB) and its degradation products, 3-chlorobenzidin e (MCB) and benzidine, are of environmental concern because of their carcin ogenic nature. The suitability of a small Fourier transform ion cyclotron r esonance (FT-ICR) mass spectrometer for the analysis of these environmental contaminants in different types of matrices was explored. All the measurem ents were carried out by depositing the sample solution directly on a disk that was introduced into the mass spectrometer. This approach is very fast and simple because it requires no prior chromatographic separation or deriv atization. Calibration curves determined by collecting 70-eV electron ioniz ation mass spectra of neat samples yielded lower limits of detection of 29 and 17 pg (total amount on the solids probe) for DCB and benzidine, respect ively (based on a signal to noise ratio of greater than or equal to 2:1), w hile chemical ionization with ammonia resulted in lower limits of detection of 21 pg for DCB and 9 pg for benzidine (total amount on the solids probe) . FT-ICR analysis of sediments collected from Lake Macatawa (Holland, MI) v erified the presence of DCB in this complex, environmentally significant sa mple matrix. Laboratory experiments designed to probe biodegradation and ph otodegradation pathways showed that DCB undergoes sequential dehalogenation to yield MCB and then benzidine under exposure to microorganisms and under simulated tropospheric solar radiation. The ability of the FT-ICR to deter mine elemental compositions of compounds introduced as described above was demonstrated for one of the degradation products. (J Am Soc Mass Spectrom 1 999, 10, 1152-1156) (C) 1999 American Society for Mass Spectrometry.