L.R. Alexander

Partitioning of in vivo bound PCDDs/PCDFs among various compartments in whole blood

Abstract We have determined the in-vivo distribution in the various blood compartments of all of the PCDDs/PCDFs normally found in humans. We compare the in-vivo and in-vitro distribution of 2,3,7,8-TCDD among the protein and lipoprotein fractions. In addition, our previously presented serum method is validated for all of the 2,3,7,8-substituted PCDDs and PCDFs.

The analytical methodology and method performance for the determination of 2,3,7,8-TCDD in serum for the Vietnam Veteran Agent Orange validation study, the ranch hand validation and half-life studies, and selected Niosh worker studies

Abstract We present the changes to our published serum TCDD method including: 1) lower amount of serum required (100 g) for normal concentration levels to be measured; 2) addition of an external standard which allows for each analysis the calculation of internal standard recovery, the isomer specificity, and 10,000 RP at the time of peak detection; 3) more stringent QC requirements for a valid TCDD result; and 4) additional measures to protect against carryover from sample-to-sample. We also present a method validation and performance evaluation, along with QC results and ranges of concentration values that we determined in over 1,000 serum samples from Agent Orange, Ranch Hand, and NIOSH Worker Studies.

Safe handling of chemical toxicants and control of interferences in human-tissue analysis for dioxins and furans

The development of a comprehensive analytical program in ultratrace analyses of toxic substances requires a facility specifically devoted to synthesis activities and for making analytical standards. The development of adequate operational procedures for such a facility is described. Environmental monitoring is a key activity in protecting the laboratory worker and the analytical integrity of ongoing studies. A wipe test procedure is described that provides the information needed to pinpoint sources of contamination. Examples of operational problems and remedial actions are described for the development of a parts per trillion dioxin analytical method. 8 references, 4 figures, 3 tables.

Analysis of human serum for PCDDs/PCDFs: A comparison of three extraction procedures

Abstract We present a comparison of the lipid extraction efficiency from blood for three very different methods as well as the PCDD/PCDF distribution for two methods using serum from our quality control pools.

A method performance evaluation and lessons learned after analyzing more than 5,000 human adipose tissue, serum, and breast milk samples for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs)

Abstract Over the past 5 years, the Centers for Disease Control had analyzed more than 5,000 adipose tissue and serum samples for PCDDs and PCDFs. These samples have been collected under strict protocols for large-scale studies including: 1) The Agent Orange Vietnam Veteran Validation Study; 2) The Missouri Adipose Tissue Study; 3) The Air Force Ranch Hand Study; 4) The NIOSH Worker Study; as well as several smaller studies. Because of our extensive quality assurance program over the years, we have been able to identify several major areas of potential analytical contamination that should be avoided by laboratories performing analyses of biological samples. We also present the results of long-term stability studies of 2378-TCDD in adipose tissue and serum (5–6 years) as well as the stability of PCDDs and PCDFs after they have been extracted from the sample matrix. In addition, we discuss the results of a performance evaluation of our method which includes small interlaboratory studies with other laboratories performing PCDD and PCDF analyses in biological samples.

Synthesis and relative response factors for the 22 tetrachlorodibenzo-p-dioxins (TCDDs) by electron-impact ionization mass spectrometry

Abstract We report the response factors of all of the tetrachlorodibenzo-p-dioxins (TCDDs) relative to 2, 3, 7, 3-TCDD by electron-impact ionization mass spectrometry. We used CP SIL 88 capillary column interfaced a ZAB-2F high-resolution mass spectrometer operating at 10,000 resolving power

Synthesis of N-(5-vinyl-1,3-thiazolidin-2-ylidene)phenylamine and analysis of oils implicated in the spanish toxic oil syndrome for its presence

Previous reports have implicated 1-phenyl-5-vinyl imidazolidine-2-thione (PVIZT), a cyclic reaction product of aniline and naturally occurring rapeseed oil isothiocyanates, as the potential causative agent of the Spanish toxic oil syndrome (TOS). This report describes the synthesis, preliminary characterization and analysis of that reaction product, which has been identified as N-(5-vinyl-1,3-thiazolidin-2-ylidene)phenylamine (5-VTPA) rather than PVIZT. Oil samples (n = 21) that contained fatty acid anilides and were epidemiologically linked to TOS were analysed for the presence of 5-VTPA by extraction of the oil with methanol and clean-up on an ion-exchange column, followed by capillary gas chromatography-mass spectrometry using selected ion detection. A limit of detection of less than 500 ppb was established for these analyses. No 5-VTPA could be detected, however, in any of the TOS oils. As 5-VTPA was shown to be unstable in both heated and unheated food oils, it is possible that the compound had been lost from the oils since the time of the epidemic in 1981. However, no direct evidence for the involvement of 5-VTPA in TOS could be obtained in this study.

A quality assurance program for large-scale studies measuring 2,3,7,8-tetrachlorodibenzo-p-dioxin in human serum

Abstract A quality assurance program (comprised of method quality control and data quality assessment procedures) is reported for measuring 2,3,7,8-tetrachlorodibenzo-p-dioxin in human serum by GC/MS. This program was successfully applied to more than 1,000 serum specimens and more than 400 quality control samples from three major studies.

Laboratory quality assessment procedures for serum dioxin and furan measurements: U.S. Air Force Ranch Hand and Centers for Disease Control Vietnam veteran, National Institute for Occupational Safety and Health chemical workers, and Seveso, Italy, studies

Abstract An overview of the Centers for Disease Control (CDC) Quality Assurance program, focusing on data quality assessment procedures for serum dioxin/furan measurements, is presented.

Photodecomposition of 1,2,3,4- and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in water-alcohol media on a solid support

We used a hydrophobic solid support, octadecylsilylated silica gel (C18), packed in a quartz column as a reaction medium for the photolysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD). When we exposed the column to a 450 W UV lamp, the adsorbed 1,2,3,4-TCDD or 2,3,7,8-TCDD in 10% 2-propanol/water decomposed completely in 20 minutes and 5 minutes, respectively. The large estimated partition coefficient of 1,2,3,4-TCDD in 10% 2-propanol/water (> 1000) indicates that on the C18 stationary phase, both the saturated hydrocarbon chains and the absorbed 2-propanol may act as proton donors and accelerate the photolysis. In direct sunlight, the adsorbed 1,2,3,4-TCDD in 10% 2-propanol/water decomposed much faster than in a nonaqueous solvent (50% 2-propanol/methanol). This solvent effect is advantageous for the practical use of the C18 photolysis process in aqueous waste treatment. We have demonstrated that complete C18 trapping with continuous photodecomposition of TCDD contained in an aqueous alcohol waste is possible.