P.W. Albro

Quantitative characterization of polychlorinated biphenyl mixtures (aroclors® 1248, 1254 and 1269) by gas chromatograpy using capillary columns

Abstract The polychlorinated biphenyl (PCB) compositions of Aroclors 1248, 1254 and 1260 have been determined using gas chromatography. A highly efficient glass capillary coated with teh moderately polar Dexsil 410 served as the primary column. Pairs of isomers not resolved on Dexsil 410 were easily distiguished on short, less efficient capillaries coated with Silar 5c, Apiezon L, or OV-25. The advantages associated with the high selectivity of moderately polar columns outweighed the high column efficiencies associated with non-polar phases, permitting not-very-efficient columns to provide the needed information. Meaningful quantitation was obtained through the use of the hydrogen flame ionization detector. These Aroclors, now characterized in terms of the relative molar percentages of approximately 100 different PCBs. can be used as secondary standards to obtain relative molar responses for electron capture detectors. This will permit valid application of quantitative gas- liquid chromatography to environmental samples.

Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on lipid profiles in tissue of the Fischer rat.

Female Fischer 344 rats were given single oral doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 10, 50 or 100 microgram/kg, and sacrificed 1, 3, 10, 14 or 21 days later. The fatty livers caused by a sub-lethal dose of TCDD involved a temporary increase in triglyceride and free fatty acid levels, with a persistent decrease in levels of sterol esters. In contrast, the fatty livers resulting from a lethal dose of TCDD involved a large increase in cholesterol esters and free fatty acids, with little change in triglyceride levels. These changes appeared to result in part from damage sustained by lysosomes. TCDD also altered the lipoprotein composition of the serum, the fatty acid composition of various lipid classes in liver and serum, and the ultrastructure of the liver (formation of myeloid bodies). A rapid, dose-dependent effect of TCDD, was the elevation of levels of organic-soluble fluorescent pigment in the heart. This pigment was found to match a previously characterized fraction of lipofuscins in fluorescence spectrum and chromatographic properties. The relatioship of these observations to a possible mechanism of toxicity for TCDD involving radical-induced lipid peroxidation is discussed.

Chromatographic and biological aspects of the

Abstract The chromatographic and bicohemical aspects of the phthalate esters have been reviewed with focus on their increasing occurence in the environment their physical and biological properties as well as the salient chromatographic (gas—liquid, thin-layer, liquid—liquid) procedures that have been employed for their separation and identification.

The use of radioimmunoassay for the detection of polychlorinated dibenzo-p-dioxins in fish samples

Abstract Because of the increasing numbers of environmental samples requiring analysis for polychlorinated dibenzo-p-dioxin (PCDD) contamination, a need exists for screening techniques, such as radioimmunoassay (RIA), that will facilitate the elimination of PCDD free samples from time-consuming conventional analysis. The RIA for the detection of PCDDs was interfaced with an extraction and cleanup procedure, and its performance was assessed using extensively and minimally cleaned-up Lake Trout samples. Sample size appeared to influence assay performance, probably because of its relationship to the specific detection limit: the larger the sample size that can be analyzed without adversely affecting the amount of TCDD detectable, the lower will be the specific detection limit. However, larger than optimal samples narrowed the assays working range, adversely affected dose response, and raised the detection limit. The working range of the assay results from a compromise between the required degree of cleanup and sample size.

In vitro studies of the inhibition of protein kinase C from rat brain by di-(2-ethylhexyl)phthalate

The environmental contaminant di(2-ethylhexyl)phthalate (DEHP) has been shown to inhibit the phosphorylation of histone by purified protein kinase C (PK-C) from rat brain in a concentration-dependent manner. The inhibition does not involve making the substrate unavailable, although DEHP does bind to some extent to histone. DEHP displaces phorbol dibutyrate from PK-C, indicating that DEHP binds to the regulatory domain of the enzyme. Since DEHP does not affect the PK-C dependent phosphorylation of protamine, DEHP probably does not bind at the catalytic site. DEHP non-competitively blocked activation of PK-C by either phosphatidyl serine or calcium ion. Inhibition of histone phosphorylation by DEHP was enhanced if diglyceride was present, and the enhancement was stereoselective for the isomeric form of the diglyceride. The mechanism of the inhibition is thought to involve interference with the interaction between calcium ion and the regulatory domain of PK-C, and would have significance only for those PK-C substrates that require calcium activation of the enzyme. Thus the presence of DEHP in the high nanomolar concentration range alters the effective substrate specificity of PK-C.

Purification and characterization of pesticidal synergists : I. Piperonyl butoxide

Abstract Piperonyl butoxide in greater than 99% purity could be obtained from technical material after a single chromatographic separation on Florisil. Among the identifiable impurities in technical grade material were diethyleneglycol monobutyl ether, dihydrosafrole, 6-methyl dihydrosafrole, 6-propyl piperonyl methoxide, 6-propyl piperonal, 6-chloromethyl dihydrosafrole, 6-propyl piperonylic alcohol, 2-propyl-4,5-dimethoxybenzyl n -butyldiethyleneglycol ether, bis(2-propyl-4,5-methylenedioxyphenyl) methane and di(2-propyl-4,5-methylenedioxybenzyl) ether.

Use of dimethyl sulfoxide as solubilization agent in the detection of 2,3,7,8-TCDD by radioimmunoassay

Abstract Immunoassays are potentially valuable tools for use in screening environmental samples for a broad range of contaminants, such as polychlorinated dibenzo-p-dioxins (PCDDs). The performance of the radioimmunoassay (RIA) for PCDDs was characterized using 4 solubilization systems: Cutscum, Triton, horse serum, and dimethyl sulfoxide (DMSO). The DMSO based assay appeared to perform best at low 2,3,7,8-TCDD levels. The effects of assay incubation time and hapten storage conditions on the DMSO based assay were assessed. The separation of bound from unbound radioactivity was accelerated without adversely affecting assay performance. Further assay development through the use of an alternative labelled hapten is considered.

Hepatic microsomal NADPH-cytochrome P-450 reductase from little skate, Raja erinacea. Comparison of thermolability and other molecular properties with a mammalian enzyme

Components of little skate (an elasmobranch) and rabbit hepatic microsomal cytochrome P-450 dependent monooxygenase systems were examined for differences which might explain the decreasing xenobiotic-metabolizing activity of little skate microsomes assayed at temperatures above 30 degrees C. The proportion of saturated fatty acids in microsomal lipids and the habitat temperature are both lower in skate as compared to rabbit, which is consistent with the known adaptive pattern. The more thermolabile enzyme of the skate system in microsomal preparations is NADPH-cytochrome P-450 reductase. The optimal assay temperature for purified skate reductase (30 degrees C) is 10 degrees C lower than that for the purified rabbit reductase. The purified skate reductase differs from rabbit reductase in monomeric molecular weight, in peptides produced by partial proteolysis, in immunochemical properties, but not in flavin content.

DEVELOPMENT AND RELIABILITY OF A RADIOIMMUNOASSAY FOR 2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN

ABSTRACT The developmental problems and a general procedure for a radioimmunoassay for 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) are briefly described. The principle is typical of competitive binding assays. The reliability of the method for determining TCDD in human fat was studied statistically. A reliable sensitivity in human fat at 95% confidence of accurate detection was 100 picograms.

Thin-layer and gas-liquid chromatography of derivatives of isomeric chlorophenols : Chlorophenyl fluorosulfonyl-benzenesulfonates and related compounds

Abstract The thin-layer and gas-liquid chromatography of derivatives of the isomeric chlorophenols, e.g. the isomeric chlorophenyl fluorosulfonyl-benzenesulfonates, were compared with the respective precursor isomeric fluorosulfonyl-benzenesulfonyl chlorides and acaricidal chlorophenyl benzenesulfonates. The thin-layer chromatographic investigation utilized four solvent systems and five electron-acceptor reagents to separate and distinguish the various isomeric derivatives. Gas-liquid chromatography was best accomplished using 5% OV-17 and SE-30 with flame ionization detection.