Donald F. Groce

Gas chromatographic/mass spectrometric analysis of human serum for non-ortho (coplanar) and ortho substituted polychlorinated biphenyls using isotope-dilution mass spectrometry

Abstract We have synthesized in our laboratory all of the totally carbon-13-labeled PCBs normally found in human tissues. The mixture of carbon-13-labeled PCBs consists of more than 50 congeners including the 13 c 12 -labeled, coplanar, non-ortho substituted PCBs. We used this spiking material to prepare analytical standards at various concentration levels, and established standard curves using isotope-dilution mass spectrometry for each congener over a range of concentrations normally found in human samples. The PCBs were analyzed on a Finnigan MAT 4500 in either the electron-impact or negative-ion chemical ionization mode on a DB-5 capillary column.

Use of reference pools to compare the qualitative and quantitative determination of polychlorinated biphenyls by packed and capillary gas chromatography with electron capture detection. Part 1. Serum

Serum for reference pools of in vivo polychlorinated biphenyls (PCBs) was obtained from four goats that had received one dose (100 mg kg-1) of a selected technical Aroclor (AR) (1016, 1242, 1254 or 1260) and were allowed to recover for 30 d. These pools were used to assess the differences in an analytical method that determines and quantifies PCBs using packed-column gas chromatography (PCGC) (quantified on the basis of mean mass percent. data for grouped PCB peaks) and capillary-column gas chromatography (CCGC) (quantified on the basis of percent. composition data for specific congeners). With CCGC, results were statistically significantly different (p less than or equal to 0.0002) from results with PCGC for ARs 1016, 1242 and 1254 but not for AR 1260 (p = 0.23). When comparing these gas chromatographic methods using bovine serum spiked in vitro with the same ARs at 17-25 p.p.b., it was found that the methods were not statistically significantly different for any of the ARs (p = 0.30-0.92). Levels of serum PCB determined by the two methods for 12 persons, divided into two groups according to exposure, were compared using the paired t-test. Group 1 consisted of three persons with dietary and/or environmental exposure; one with dietary and/or environmental exposure in addition to occupational exposure dating back 20 years. Group 2 consisted of eight persons with recent occupational exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Acute response of rat liver microsomal lipids, lipid peroxidation, and membrane anisotropy to a single oral dose of polybrominated biphenyls

Liver microsomal lipids and lipid peroxidation activities were examined in adult male rats at intervals over a 2-mo period after the administration of a single oral dose of 0 or 500 mg/kg of FireMaster BP-6 in corn oil. Microsomal lipids were markedly altered in the polybrominated biphenyl- (PBB-) dosed animals at the earliest time examined (1 wk), and these changes persisted throughout the remainder of the study. An early decrease in the cholesterol-phospholipid ratio was noted, which probably contributed to the significant decrease in the steady-state fluorescence anisotropy demonstrable in both intact microsomes and in liposomes prepared from microsomal lipid extracts. Significant concentrations of PBBs were present in dosed rat microsomes, but the changes in anisotropy appeared to result from membrane lipid alterations rather than from a direct perturbation by PBBs. Iron ascorbate-induced peroxidation was also greatly enhanced in dosed rat microsomes, even when rats were maintained on a low-iron (25 ppm) diet. These early alterations in membrane fluidity and peroxidative capacity of microsomes may ultimately contribute to the hepatotoxicity of PBBs.

Long-term effects of a single oral dose of polybrominated biphenyls on serum and liver lipids in rats☆

Adult (5 months) male Sherman strain rats received a single dose of either 0 or 500 mg polybrominated biphenyls (PBB) in corn oil/kg body weight by stomach tube. After an 18-month recovery period, serum and liver samples were examined. The primary serum lipid response was an increase in cholesterol (both free and esterified) and in total phospholipids. The percentage of esterified cholesterol was not significantly different from that of the controls, and no significant differences in the cholesterol ester fatty acid composition were observed. Serum triglycerides were also unaffected. In the PBB-dosed animals, the total hepatic fatty acids contained significantly less palmitic acid and more stearic acid, consistent with an increase in palmitic acid chain elongation activity. No significant differences could be detected in the n-3 or n-6 acids except for a slight decline in the content of 22:6 (n-3). Hepatic microsomal phospholipids were slightly higher (per milligram protein) in the PBB-dosed animals, and the cholesterol content was lower. Consequently, the cholesterol-phospholipid ratio was reduced, and microsomes from the latter group appeared to have an altered lipid domain on the basis of steady-state fluorescence anisotrophy measurements. In addition, total hepatic thiobarbituric acid-reactive substances (assayed as malondialdehyde) were significantly increased in the PBB-dosed animals. This observation appeared to reflect an increased susceptibility to peroxidative stress in the latter group, probably resulting from reduced membrane antioxidant concentrations. The PBB-dosed rats had significantly lower serum retinol levels and a reduced content of this vitamin in liver microsomes. Microsomes were also deficient in alpha-tocopherol in the PBB-dosed animals, although serum levels were normal.

Stunted growth, increased mortality, and liver tumors in offspring of polybrominated biphenyl (PBB) dosed Sherman rats

Firemaster FF-1, a polybrominated biphenyl (PBB) mixture, was dissolved in corn oil and given as a dose of 200 mg/kg body weight to Sherman rats on d 7 and 14 of pregnancy. Control rats received equivalent doses of corn oil alone. Selected pups and all dams were killed 1 mo after pups were weaned. A total of 50 male and 50 female offspring per group were followed until they were 2 yr old. The livers of offspring killed at the ages of 2 mo and 2 yr had PBB levels of 2,4 (SD 1.2) and 0.8 (SD 0.65) mg/kg for females and 3.0 (SD 1.6) and 0.6 (SD 0.37) mg/kg for males, respectively. The incidence of hepatocellular carcinomas was 3/51 (5.9%) and 4/41 (9.6%) after 2 yr in females and males, respectively. Hepatocellular carcinomas were not observed among the controls. Neoplastic (hyperplastic) nodules of the liver were present in 9/51 (17.6%) and 2/41 (4.9%) of exposed females and males, respectively, whereas only 2/48 (4.2%) of control females and no control males had neoplastic (hyperplastic) nodules. Body weights were lower in PBB-exposed rats at ages 1, 6, 12, and 24 mo. Survival rates from birth to weaning were lower in PBB-exposed pups (89%) than in controls (98%). Mortality was two times higher in PBB-exposed males (64%) than in control males (32%) after 2 yr. Transplacental PBB exposure and exposure through milk resulted in PBB body burdens in the offspring still measurable at the end of their lifespan. These offspring had increased mortality rates and lower body weights than controls, and they developed hepatocellular carcinomas.

Investigation of hyperkeratotic activity of polybrominated biphenyls in Firemaster FF-1.

A polybrominated biphenyl (PBB) mixture was fractionated by normal-phase preparative high-performance liquid chromatography. The hexane fractions were concentrated and applied to rabbit ears. Only the most polar fraction produced hyperkeratosis on the rabbit ears. This active fraction was subfractionated by using the same procedure. Again, the extent of hyperkeratotic activity increased with increasing polarity. The PBBs of the largest concentration levels in the active fraction were purified by preparative gas chromatography and tested on rabbit ears. The major compounds did not demonstrate hyperkeratotic activity.

Synthesis of tetrachloro-, pentachloro-, and hexachlorodibenzofurans from the pyrolysis of polychlorinated biphenyls

Abstract We have used a pyrolysis procedure described by Mazer et al. and reaction routes described by Buser and Rappe to synthesize and characterize the 38-Tetrachlorodibenzofurans, 28-Pentachlorodibenzofurans, and 16-Hexachlorodibenzofurans. By using quantitative aliquots of the reaction product mixtures and a quantitative internal standard we were able to semiquantitatively assess the relative importance of various reaction pathways. We propose a number of general mechanistic rules concerning polychlorinated biphenyl (PCB) pyrolysis.