Richard D. Brown

Toxicology Studies of a Chemical Mixture of 25 Groundwater Contaminants I. Chemistry Development

As part of an effort to evaluate the toxicology of a chemically defined mixture of 25 frequently detected groundwater contaminants, we report here the formulation and analytical chemistry of this mixture. Many problems were anticipated, including limitation of solubility, chemical interactions, and extreme volatility in the aqueous solution of 25 chemicals. The final technically achievable stock solution was prepared based on EPA survey concentrations of these chemicals in groundwater around hazardous waste disposal sites, their toxicity information, and solubility of the individual compounds in the matrix of the aqueous solution of these 25 chemicals. Because the anticipated animal studies were to be conducted at various laboratories, for ease of handling and maximum stability, the stock solution was stored or shipped as two substock solutions: an organic substock with 18 neat organic chemicals in a glass vial sealed with minimum headspace and an aqueous substock solution with 6 metals of various salt forms and phenol. The concentrations of the solutions were such that direct mixing of the organic and aqueous substocks produced the desired high dose level for the animal experiments. Analyses of all 25 chemicals in the drinking water mixture required six different chromatographic and spectroscopic methods. Some loss of organic volatiles during mixing of the substocks and during the first 24 hr following preparation did occur. However, the concentrations of acetone, phenol, and all the metals remained constant during preparation. Solutions held under simulated animal cage conditions for 96 hr showed losses of the organic volatiles; the majority of which occurred within the first 24 hr. This study shows that it is possible to conduct animal experiments on an aqueous mixture containing 25 groundwater contaminants. Furthermore, a reasonable estimate of intake of individual chemicals can be achieved provided that dosing solutions are prepared fresh at frequent intervals (e.g., 48 to 72 hr) and that comprehensive analyses are carried out.

Analysis of the brominated fire retardant decabromodiphenyl oxide for low and trace level impurities

Abstract The fire retardant, decabromodiphenyl oxide, was analyzed for the presence of impurities by high resolution gas chromatography/mass spectrometry. Traditional elution chromatographic methods were also used in an attempt to screen the sample for brominated dibenzodioxins and dibenzofurans. Results from these analyses indicated that highly brominated compounds such as decabromodiphenyl oxide could be successfully analyzed by high resolution gas chromatography for trace level impurities. Better separation of impurities was obtained with this system than with the traditionally used high performance liquid chromatography. Several brominated impurities were identified in the sample. Analysis of the sample for brominated dibenzodioxins and dibenzofurans indicated that traditional elution chromatographic systems were inadequate for separating the brominated biphenyls and diphenyl ethers from the brominated dibenzodioxins and dibenzofurans.

Identification of bromotetrachlorophenol in commercial pentachlorophenol samples

Identification et analyse quantitative par chromatographie en phase gazeuse et spectrometrie de masse

Identification of Chlorinated Phenyl and Phenoxy Substituted Dibenzodioxin, Dibenzofuran, and Diphenyl Ether Homologs in Commercial Grade Pentachlorophenol

Abstract As part of a bioassay study by the National Toxicology Program, technical grade pentachlorophenol (PCP) was analyzed for chlorinated impurities using capillary gas chromatography/mass spectrometry (GC/MS). Several high molecular weight impurities eluting after octachlorodibenzodioxin were detected during the analysis of this material. These impurities were tentatively identified according to structural classes as chlorinated triphenyl ethers, dibenzodioxin phenyl ethers, phenyldibenzodioxins, and dibenzofuran phenyl ethers.

Characterization of Sulfonic Acid Isomers of Dehydrothio- p -toluidine

Dehydrothio-p-toluidine sulfonic acid (DTSA) is commonly used as a dye intermediate. It is typically produced by sulfonation of the product obtained from fusion of p-toluidine and sulfur. In addition to the major component, 2-(4-aminophenyl)-6-methyl-7-benzothiazolyl-sulfonic acid (APM-7-BSA), a commercial sample of DTSA, characterized for the National Toxicology Program, was found to contain sulfonic acid isomers of the major component which have not been described in the chemical literature.

Analysis of halogenated hydrocarbons in trans-1,2-dichloroethylene by thick-film, wide-bore, capillary gas chromatography

Chemical analyses performed in support of toxicological studies must provide a thorough characterization of the impurities in the test chemical. This often includes the need for efficient chromatographic separation of compounds which are closely related to the major component and to each other and are present in the sample at low concentrations relative to the major component. The following work was performed in support of toxicological studies of trans-1,2-dichloroethylene. These studies required that several specific halogenated hydrocarbon impurities be identified and quantitated. Some of these impurities are very similar in volatility to trans-1,2-dichloroethylene. Several gas chromatographic systems have been described for the analysis of halogenated hydrocarbons in complex matrices but these systems were found to be incapable of providing the separation necessary to perform this analysis. The gas chromatography/mass spectrometry (GC/MS) system described herein may be adaptable to the analysis of low concentration impurities in similar technical grade solvents and especially the separation, identification, and quantitation of rapidly eluting volatile components in these solvents.