Donald G. Patterson

2,3,7,8-tetrachlorodibenzo-p-dioxin levels in adipose tissue of persons with no known exposure and in exposed persons

Abstract Adipose tissue tetrachlorodibenzo-p-dioxin (TCDD) levels were determined for 128 persons with no known exposure and for 51 exposed persons. For persons with no known exposure, adipose TCDD levels ranged from nondetectable to 20.2 ppt with 95% of the levels at 16.6 ppt or less. For the 51 exposed persons, adipose tissue TCDD levels ranged from 3.7–750 ppt.

1H-NMR spectra of the 22 tetrachlorinated dibenzo-p-dioxins

Abstract The 22 tetrachlorinated dibenzo-p-dioxins (TCDDs) were prepared by reacting the dipotassium salt of a chlorinated catechol with a chlorinated benzene or an ortho-chlorinated nitrobenzene. Some of the purified reaction products contained isomers formed by the Smiles rearrangement. The 300 MHz 1 H-Nuclear Magnetic Resonance (NMR) spectra of these reaction products are presented. The spectra were assigned by spectral analysis and by comparison of NMR integrations with data from Gas Chromatographic-Flame Ionization Detection (GC-FID) measurements. The uniqueness of the spectra makes NMR measurement an efficient means for the isomer-specific determination of the 22 TCDDs at the microgram level.

Isomer identification of chlorinated dibenzo-p-dioxins by orthogonal spectroscopic and chromatographic techniques

Isomer differentiation of chlorinated dibenzo-p-dioxin (CDD) isomer pair components was examined by three orthogonal chromatographic (gas chromatography, liquid chromatography, and micellar electrokinetic chromatography) techniques and three orthogonal spectroscopic (Fourier transform infrared and carbon-13 and proton nuclear magnetic resonance) techniques. Synthetic CDD isomer pair mixtures from the same sample set were separated by methods using independent partitioning dynamics and identified by spectroscopic methods using independent energy/structure transformations. This integrated approach using orthogonal methods minimizes isomer identification error probability and results in an excellent agreement among methods in isomer assignment.

Importance of enhanced mass resolution in removing interferences when measuring volatile organic compounds in human blood by using purge-and-trap gas chromatography/mass spectrometry

The number of volatile organic compounds (VOCs) that can be purged from human blood is so great that they cannot be separated completely by capillary gas chromatography. As a result, the single-mass chromatograms used for quantitating the target compounds by mass spectrometry have many interferences at nominal (integer) mass resolution of a quadrupole mass spectrometer. The results of these interferences range from small errors in quantitation to completely erroneous results for the target VOCs. By using a magnetic sector mass spectrometer, these interferences at nominal mass can be removed at higher resolution by lowering the ion chromatogram windows around the masses of interest. At 3000 resolution (10% valley definition), unique single-ion chromatograms can be made for the quantitation ions of the target VOCs. Full-scan mass data are required to allow the identification of unknown compounds purged from the blood. By using isotope-dilution mass spectrometry, most target VOCs can be detected in the low parts per trillion range for a 10-mL quantity of blood from which the VOCs have been removed by a purge-and-trap method.

Interlaboratory testing study on 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran isomer standard solutions

Abstract Carefully prepared isomer standard solutions of all 17 of the 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and their corresponding crystalline materials were provided to nine environmental analytical laboratories for the purpose of performing a round robin study of the accuracy and reliability of the standard solutions. Consensus values were determined for each isomer. Good correlation was found between the target values and the consensus values.

Molecular geometry/toxicity correlations for laterally tetrachlorinated dibenzo-p-dioxins by Fourier transform infrared spectroscopy

Abstract Correlations between infrared data and polychlorinated dibenzo-p-dioxin (PCDD) LD–50 values suggest that molecular geometry, polarizability and steric PCDD/receptor interactions are associated with isomer toxicity.

Relationships between concentrations of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin serum and personal characteristics in U.S. Army Vietnam veterans

Abstract We examined the association between personal characteristics and concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in blood serum of 640 male U.S. Army Vietnam veterans. TCDD concentrations ranged from 1.1 to 16.2 pg/g wet weight (ppt) with a geometric mean of 3.8 ppt consistent with no past heavy exposure to TCDD. TCDD concentrations increased with body mass index on the order of 0.3 ppt per 10 kg of body weight for veterans of the same height. Concentrations were about 50% greater for black veterans aged 45 compared to black veterans aged 37. We found no association between age and TCDD concentration in non-blacks. Veterans living in the western U.S. had slightly lower concentrations than those living elsewhere. TCDD concentrations tended to be slightly greater in veterans who reported spraying or mixing herbicides while employed in farming or ranching and in those who reported employment at incinerators. Relationships between concentrations of TCDD and personal characteristics were similar for 94 Vietnam-era veterans who had served in the continental U.S. or Germany.

Analysis of tetra-through octachlorinated dibenzo-p-dioxins by gas chromatography/Fourier transform infrared spectroscopy

Abstract The structures of individual polychlorinated dibenzo-p-dioxin isomers in each synthetic isomer pair were assigned by qualitative valence-bond evaluations and empirically derived quantitative estimations of ether linkage asymmetric stretching frequencies.

Purification of PCDD synthesis products by reversed-phase liquid chromatography with pyrenylethylsilylated and octadecylsilylated silica gel

Abstract Pure chlorinated dioxin congeners (including 20 of the 22 TCDDs) were isolated from synthetic reaction mixtures by reversed phase liquid chromatography on two stationary phases.

Structure/retention time correlations for the 22 tetrachlorodibenzodioxin isomers by gas chromatography/matrix isolation Fourier transform infrared spectroscopy

Abstract The structures of the individual tetrachlorodibenzodioxin isomers previously proposed from a chromatographically independent valence-bond analysis of infrared data were correlated with gas chromatography retention times using a CP-Sil 88 fused silica capillary column.