Two multidimensional chromatographic methods for enantiomeric analysis of o,p'-DDT and o,p'-DDD in contaminated soil and air in a malaria area of South Africa.

In rural parts of South Africa the organochlorine insecticide DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is still used for malaria vector control where traditional dwellings are sprayed on the inside with small quantities of technical DDT. Since o,p'-DDT may show enantioselective oestrogenicity and biodegradability, it is important to analyse enantiomers of o,p'-DDT and its chiral degradation product, o,p'-DDD, for both health and environmental-forensic considerations. Generally, chiral analysis is performed using heart-cut multidimensional gas chromatography (MDGC) and, more recently, comprehensive two-dimensional gas chromatography (GC×GC). We developed an off-line gas chromatographic fraction collection (heart-cut) procedure for the selective capturing of the appropriate isomers from a first apolar column, followed by reinjection and separation on a second chiral column. Only the o,p'-isomers of DDT and DDD fractions from the first dimension complex chromatogram (achiral apolar GC column separation) were selectively collected onto a polydimethylsiloxane (PDMS) multichannel open tubular silicone rubber trap by simply placing the latter device on the flame tip of an inactivated flame ionisation detector (FID). The multichannel trap containing the o,p'-heart-cuts was then thermally desorbed into a GC with time-of-flight mass spectrometry detection (GC-TOFMS) for second dimension enantioselective separation on a chiral column (ß-cyclodextrin-based). By selectively capturing only the o,p'-isomers from the complex sample chromatogram, (1)D separation of ultra-trace level enantiomers could be achieved on the second chiral column without matrix interference. Here, we present solventless concentration techniques for extraction of DDT from contaminated soil and air, and report enantiomeric fraction (EF) values of o,p'-DDT and o,p'-DDD obtained by a new multidimensional approach for heart-cut gas chromatographic fraction collection for off-line second dimension enantiomeric separation by (1)D GC-TOFMS of selected isomers. This multidimensional method is compared to the complementary technique of comprehensive GC×GC-TOFMS using the same enantioselective column, this time as the first dimension of separation.

Interindividual differences in o,p'-DDD enantiomer kinetics examined in Göttingen minipigs.

Five minipigs were given a single oral dose of a racemic mixture of o,p'-DDD (30 mg kg(-1)b.w., EF=0.49). Blood plasma and subcutaneous adipose tissue were collected for analysis, at different time-points over 180 d. At the end of the experiment also liver, kidney and brain tissue were collected. Low concentrations of o,p'-DDD still remained after 180 d in plasma (mean 0.5+/-0.3 ng g(-1)f.w.) and in adipose tissue (mean 40+/-40 ng g(-1)f.w.). The mean concentrations in liver and kidney were 500+/-300 pg g(-1)f.w. and 90+/-50 pg g(-1)f.w., respectively. The enantiomers of o,p'-DDD were isolated by HPLC and the absolute configuration of the enantiomers were determined by X-ray crystallography and polarimetry as R-(+)-o,p'-DDD and S-(-)-o,p'-DDD. The enantiomer fractions (EFs) of o,p'-DDD were determined in plasma, adipose tissue and kidney using GC/ECD equipped with a chiral column. The EFs of o,p'-DDD in the individual minipigs showed large variability, ranging from 0.2 to 0.6 after 24h in plasma and from 0.2 to 0.7 after 90 d in adipose tissue. Hence in two of the minipigs, the S-(-)-o,p'-DDD enantiomer was dominating while the other enantiomer, R-(+)-o,p'-DDD was dominating in three minipigs. We propose that a yet not identified factor related to polymorphism, regulating the metabolism and/or elimination of the enantiomeric o,p'-DDD, is responsible for the differences in enantiomeric retention of the compound in the minipigs.

Determination of chiral ratio of o,p-DDT and o,p-DDD pesticides on polysaccharides chiral stationary phases by HPLC under reversed-phase mode.

A simple and reliable HPLC method for the chiral resolution of o,p-DDT and o,p-DDD is described. The enantiomeric resolution of o,p-DDT and o,p-DDD has been achieved on Chiralpak AD-R, Chiralcel OD-R, and Chiralcel OJ-R chiral stationary phases. The mobile phases used were acetonitrile-water (50:50 [v/v]) and acetonitrile-2-propanol (50:50 [v/v]) at a flow rate of 1.0 mL/min. For both pesticides detection was done at 220 nm. The values for o,p-DDT of alpha and R(s) varied from 1.24 to 2.52 and from 0.80 to 2.47, respectively. The values of alpha and R(s) for o,p-DDD were 1.26 and 0.60, respectively.

Detection of endocrine disrupting chemicals in samples of second trimester human amniotic fluid.

Man-made chemicals that have been shown to modulate endocrine function in animal models, so-called "endocrine disrupters", are suspected to play a role in the development of male reproductive tract abnormalities and neurobehaviroal deficits in children. However in utero exposure to environmental contaminants has not been documented previously. The present study was performed to test our hypothesis that man-made chemicals can be quantified in human amniotic fluid during the second trimester. Gas chromatographic/mass spectrometric (GC/MS) analysis was performed on amniotic fluid samples (n=53) from women (n=51) undergoing routine amniocentesis with a mean (+/- SEM) age of 36.5 +/- 0.5 years and between 15 and 23 weeks of gestation. Analytes included common PCB congeners, the DDT metabolites p,p'-DDE, and o,p'-DDE as well as the pesticides: hexachlorobenzene (HCB); and the three isomers of hexachlorocyclohexane (alpha,beta and gamma-HCH). The limit of quantitation (LOQ) for PCBs was 0.01 ng/ml and for the other organochlorines contaminants is was 0.1 ng/ml. The contaminants alpha-HCH with a mean (+/- SD) concentration of 0.15 +/- 0.06 (ng/ml) and p,p'-DDE with a mean (+/- SD) concentration of 0.21 +/- 0.18 ng/ml were detected in the amniotic fluid. PCB specific congeners were detected with a much lower frequency and levels were in the range of the LOQ. Overall one in three amniotic fluid samples tested positive for at least one environmental contaminant. Therefore, we conclude that approximately one in three fetuses in the Los Angeles area are exposed to endocrine modulatory environmental contaminants in utero the consequences of which remain unknown at this time.

Organochlorine pesticide residues in muscle tissue of rainbow trout, Oncorhynchus mykiss, taken from four fish farms in León, Spain.

Levels of nine organochlorine pesticides (lindane, heptachlor epoxide, aldrin, dieldrin, endrin, o,p'-TDE, p,p'-TDE, p,p'-DDE and p,p'-DDT) were determined in muscle samples of rainbow trout, Onchorhynchus mykiss, collected from four fish farms in the province of León, in the north-west of Spain (Europe). The highest incidence percentage was for lindane (67.5%) and heptachlor epoxide (55.0%). Organochlorine residue levels detected contributed slightly to acceptable daily intakes (ADIs) established by the Food and Agriculture Organization of the United Nations and the World Health Organization (lindane 0.22-2.3%; sigma DDT 0.05-0.46%; heptachlor epoxide 10.0-71.4% and sigma dieldrin 16.7-33.3% assuming 300 g of trout muscle as a mean daily intake). The highest concentration found was for heptachlor epoxide (0.043 microgram/g).

Noninvasive in vivo 13C-NMR spectroscopy of a 13C-labeled xenobiotic in the rat.

This study demonstrates that the xenobiotic product, 1-(o-chlorophenyl)-1-(p-chlorophenyl)-2,2-dichloro-3-13C-propane can be monitored in the liver of an intact animal by in vivo 13C surface coil NMR spectroscopy after intraperitoneal administration. The carbon-13 label could be detected after a single dose of only 200 mg/kg of the product. The intrahepatic changes of the signal intensity of the labeled product were monitored as a function of time. No signals corresponding to metabolites could be detected.

The role of calcium ions and bile salts on the pancreatic lipase-catalyzed hydrolysis of triglyceride emulsions stabilized with lecithin.

Lecithin-stabilized triglyceride emulsions are subject to hydrolysis by pancreatic lipase. The time profiles of these reactions are characterized by a lag-phase and a zero-order phase. Lag phases are more pronounced with long-chain triglycerides. Ca2+ is effective in reducing the lag-phase and activating lipase. Kinetic analysis of the reactions suggests that, like previous findings by others, taurodeoxycholate (TDC) micellar solutions combine with the lipase-colipase complex to form another catalytically active enzyme form. This enzyme form exhibits reduced activity in the absence of Ca2+. In the presence of Ca2+ the mixed micelle-lipase complex becomes more active and opens a new pathway for lipolysis. It is suggested that this enzyme form can bind more easily to interfaces with different physicochemical properties. Under these conditions, Ca2+ activates the lipolysis of short-, medium-, and long-chain triglycerides by a similar mechanism. Maximum activities were measured in the presence of approximately 6 mM TDC and 30 mM Ca2+. The experimental conditions approximate the physiological conditions in the gastrointestinal tract since all of the factors studied here have been reported to be necessary for in vivo lipolysis and/or absorption of triglycerides. A mechanistic model for lipolysis in the presence of Ca2+ and the bile salt TDC is proposed which accounts for most of the experimental observations in a quantitative manner.

[Relationship between accumulation of o,p'-dichlorodiphenyl-dichloroethane in the adrenal glands and their function and structure]. / Zavisimost' mezhdu nakopleniem o,p'-dikhlordifenil-dikhloretana v nadpochechnikakh, ikh funktsiei i strukturoi

Over a periof of 12 days following introduction of o'p-dichlordiphenyl-chlorethane to dogs in a dose of 25 mg/kg a sizable accumulation of the compound in the adrenal tissue, a drastic inhibition of its function and deragment of the suprarenal cortex structure are observed. After a 28-day administration of the compound the functional and structural upsets in the adrenals gain in strength, whereas it concentration in this organ declines.

Metabolism of 1-(0-chlorophenyl)-1-(p-chlorophenyl)-2,2-dichloroethane (o,p'-DDD) in rats.

The metabolism of 14C-labeled 1-(p-chlorophenyl)-2,2-dichloroethane (o,p'-DDD) in rats was investigated. Metabolites were identified in feces and urine extracts by thin-layter chromatography (TLC), gas-liquid chromatography, and mass spectropmetry. Extracts of acidic metabolites were methylated with diazomethane for identification. Metabolites were quantitated by TLC and liquid scintillation counting. After a 100-mg oral dose to each of three rats, an average of 7.1% of the radioactivity was excreted in the urine and 87.8% in the feces within 8 days. The urine was found to contain o,p'-dichlorodiphenylacetic acid (o,p'-DDA) as well as 4-hydroxy-, 3-hydroxy-, and 3,4-dihydroxy-substituted o,p'-DDA. The serine and glycine conjugates of o,p'-DDA were also identified. In addition to the above metabolites the feces contained o,p'-DDD. 1-(o-chlorophenyl)-1-(P-chlorophenyl)-2-chloroethylene, and the aspartic acid conjugate of o,p'-DDA. The presence of aromatic mono- and dihydroxylated o,p'-DDD was also detected in feces.