A gas chromatography-isotope dilution high-resolution mass spectrometry method for quantification of isomeric benzo[a]pyrene diol epoxide hemoglobin adducts in humans.

We developed a gas chromatography-isotope dilution high-resolution mass spectrometry (GC-ID-HRMS) method for quantifying isomers of benzo[a]pyrene (BaP) tetrol metabolites resulting from hydrolysis of benzo[a]pyrene-diol-epoxide hemoglobin (BaPDE-Hb) adducts. Acid hydrolysis of BPDE-Hb adducts extracted from human blood samples yielded isomers of benzo[a]pyrene-tetrahydrotetrols, (+/-)-BaP-r-7,t-8,t-9,c-10-tetrol (BPTI-1), (+/-)-BaP-r-7,t-8,t-9,t-10-tetrol (BPTI-2), (+/-)-BaP-r-7,t-8,c-9,t-10-tetrol (BPTII-1), and (+/-)-BaP-r-7,t-8,c-9,c-10-tetrol (BPTII-2). The isomeric BaP tetrols were isolated from the matrix by liquid-liquid extraction, and then further purified by solid-phase extraction. Following silylation with N-methyl-N-(trimethylsilyl)-trifluoroacetamide, the analytes were measured by GC-HRMS, using electron ionization. We have found detectable concentrations in the low fmol range for BPTII-1 and BPTI-1 in all donors tested. The mean BaP adduct levels for smoking donors (n = 9) were 0.022 fmol/mg hemoglobin for BPTII-1 and 0.070 fmol/mg hemoglobin for BPTI-1. The mean BaP adduct levels with hemoglobin for non smoking donors (n = 6) was 0.021 fmol/mg hemoglobin for BPTII-1 and 0.105 fmol/mg hemoglobin for BPTI-1.

Analysis of polyethylene by using cyclopentadienyl cobalt chemical ionization combined with laser-induced acoustic desorption/fourier transform ion cyclotron resonance mass spectrometry.

A new mass spectrometric method has been developed for the analysis of low molecular weight polyethylene (PE). Laser-induced acoustic desorption (LIAD), combined with chemical ionization by the cyclopentadienyl cobalt radical cation (CpCo.+) in a Fourier transform ion cyclotron resonance mass spectrometer, produces predominantly a quasimolecular ion, (R + CpCo - 2H2).+, for each PE oligomer (R). An examination of artificial alkane mixtures revealed no mass bias for alkanes of differing molecular weights. However, the success of the LIAD/CpCo.+ CI technique depends greatly upon the LIAD sample preparation method used. Several sample preparation methods were evaluated, and pneumatically assisted spin coating was concluded to provide the best mass spectra as a result of its ability to provide uniform PE coverage on the LIAD foils. The molecular weight distributions measured for several low molecular weight PE samples (200-655) were found to be in good agreement with manufacturers' values as determined by gel permeation chromatography.

Laser-induced acoustic desorption/fourier transform ion cyclotron resonance mass spectrometry for petroleum distillate analysis.

Laser-induced acoustic desorption (LIAD) coupled with a 3-T Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR) allows the simultaneous analysis of both the nonpolar and polar components in petroleum distillates. The LIAD/FT-ICR method was validated by examining model compounds representative of the various classes of polar and nonpolar hydrocarbons commonly found in petroleum. LIAD successfully desorbs all the compounds as intact neutral molecules into the FT-ICR. Electron ionization (EI) at low energies (10 eV) and chemical ionization using cyclopentadienyl cobalt radical cation (CpCo*+) were employed to ionize the desorbed molecules. The EI experiments lead to extensive fragmentation of many of the hydrocarbon compounds studied. However, the CpCo*+ ion ionizes all the hydrocarbon compounds by producing only pseudomolecular ions without other fragmentation, with the exception of one compound (*CH3 loss occurs). Examination of two different petroleum distillate samples revealed hundreds of compounds. The most abundant components have an even molecular weight; i.e., they are likely to contain no (or possibly an even number of) nitrogen atoms.

Analysis of saturated hydrocarbons by using chemical ionization combined with laser-induced acoustic desorption/Fourier transform ion cyclotron resonance mass spectrometry.

Laser-induced acoustic desorption (LIAD), combined with chemical ionization by the cyclopentadienyl cobalt radical cation (CpCo.+), is demonstrated to facilitate the analysis of saturated hydrocarbons by Fourier transform ion cyclotron resonance mass spectrometry. The LIAD/CpCo.+ method produces unique pseudomolecular ions for alkanes from C(24)H(50) to C(50)H(102). These alkanes were tested individually and in artificial mixtures of up to seven components. Only one product ion, [R + CpCo - 2H(2)].+, was detected for each alkane (R). The product ions' relative abundances correspond to the relative molar concentration of each alkane in mixtures. These findings provide a solid groundwork for the future application of this method for hydrocarbon polymer analyses.