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A simple and rapid headspace method for gas chromatographic determination of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in drinking water was developed. Acidic methanol esterification followed by a headspace technique using a capillary column gas chromatograph (GC) equipped with an electron capture detector (ECD) was applied to determine the levels of DCAA and TCAA in drinking water. The major advantages of this method are the use of acidic methanol as the derivatization agent instead of the hazardous diazomethane, and esterification is carried out in water instead of organic solvent. DCAA and TCAA methyl esters produced in the reaction were determined directly by a headspace GC/ECD method. The linear correlation coefficients at concentrations ranging from 0 to 60 microg/L were 0.992 and 0.996 for DCAA and TCAA, respectively. The relative standard deviations (RSD, %) for the determination of DCAA and TCAA in drinking water were 15 and 21.3%, respectively (n=3). The detection limits of this method were 3 and 0.5 microg/L for DCAA and TCAA, respectively, and the recovery was 68-103.2% for DCAA and TCAA.

Adsorption performance of 5 GACs were compared on two abundant haloacetic acids (HAAs) as disinfection by-products (dichloroacetic acid and trichloroacetic acid). The adsorption behaviours of the two HAAs were well correlated with Langmuir equation. When the two HAAs co-existed, trichloroacetic acid tended to be adsorbed more easily. The adsorption capacity of a foreign GAC-A for dichloroacetic acid was 4.4-5.7 times that of domestic GACs, and 3.8 times that of another foreign GAC-B, while the adsorption capacity of a foreign GAC-A for trichloroacetic acid was 4.0-5.4 times that of domestic GACs, and 2.6 times that of another foreign GAC-B. The equilibrium study of competitive adsorption between dichloroacetic acid and trichloroacetic acid on GAC-A demonstrates that the relative adsorption capacity of HAAs has a linear increase with their relative equilibrium concentration. The adsorption capacity for trichloroacetic acid is sensitive to changes at its equilibrium concentration greater than that for dichloroacetic acid.

A sensitive and reproducible method is described for the analysis of trichloroacetic acid in urine and 1,1,1-trichloroethane in blood using dynamic headspace GC/MS. Samples were analyzed using the soil module of a modified purge and trap autosampler to facilitate the use of disposable purging vessels. Coefficients of variation were below 3.5% for both analytes, and response was linear in the range of 0.01-7.0 microg/ml for trichloroacetic acid and 0.9 ng/ml-2.2 microg/ml for 1,1,1-trichloroethane. Attempts at using dynamic headspace for the analysis of trichloroethanol in urine were unsuccessful.

Hemoglobin (Hb) can take direct electron-transfer reactions after being entrapped in poly-3-hydroxybutyrate (PHB) film. A pair of well-defined, quasi-reversible cyclic voltammetric peaks is thus obtained at an Hb-PHB modified pyrolytic graphite electrode. The anodic and cathodic peaks are located at -224 and -284 mV for a pH 5.0 acetate buffer solution. Meanwhile, the peroxidase activity of the protein in the membrane has been greatly enhanced, with the apparent Michaelis-Menten constant calculated to be 1076 microM. According to the direct electron transfer property and enhanced peroxidase activity of Hb in the membrane, a Hb-PHB based hydrogen peroxide biosensor is prepared, with a linear range 6.0 x 10(-7) to 8.0 x 10(-4) M. The pathway of reductive dehalogenation of trichloroacetic acid is also discussed in detail. The highly reduced form of Hb produced in PHB film can be used to dechlorinate di- and monochloroacetic acid. The catalytic ability of Hb toward the reduction of nitric oxide has been investigated as well. Due to its biodegradability, low cost, chemical inertness, and especially its biocompatibility and non-toxicity, PHB would be a desirable film in the sensor field.

Soil is an important compartment in the environmental cycling of trichloroacetic acid (TCA), but soil TCA concentration is a methodologically defined quantity; analytical methods either quantify TCA in an aqueous extract of the soil, or thermally decarboxylate TCA to chloroform in the whole soil sample. The former may underestimate the total soil TCA, whereas the latter may overestimate TCA if other soil components (e.g. humic material) liberate chloroform under the decarboxylation conditions. The aim of this work was to show that extraction and decarboxylation methods yield different TCA concentrations because the decarboxylation method can also determine "bound" TCA. Experiments with commercial humic acid solutions showed there was no additional chloroform formation under decarboxylation conditions, and that all TCA in a TCA-humic acid mixture could be quantitatively determined (108 +/- 13%). Anion exchange resin was used as a provider of solid-phase TCA binding; only 5 +/- 1% of a TCA solution mixed with the resin was present in the aqueous extract subsequently separated from the resin, yet the decarboxylation method yielded mass balance (123 +/- 22%) with TCA remaining in the resin. In aqueous extraction of a range of soil samples (with or without added TCA spike), the decarboxylation method was able to satisfactorily account for TCA in the extractant + residue post-extraction, compared with whole-soil TCA (+ spike) pre-extraction: e.g. mass balances for unspiked soil from Sikta spruce and larch forest were 99 +/- 8% and 93 +/- 6%, respectively, and for TCA-spiked forest and agricultural soils were 114 +/- 13% and 102 +/- 2%. In each case recovery of TCA in the extractant was substantially less than 100%(<20% for unspiked soils, <55% for spiked soils). Extraction efficiencies were generally lower in more organic soils. The results suggest that analytical methods which utilise aqueous extraction may underestimate whole-soil TCA concentrations. Application of both methodologies together may enhance insight into TCA behaviour in soil.

There has been an accelerated expansion of deserts in the past five decades. Recent data reveal that the atmogenically formed organic compound, trichloroacetic acid (TCA) is a contributory factor in addition to anthropogenic and natural sources. The aim of this study was to use TCA as an indicator for the possible occurrence of C2-chloroacetic acids; to assess the burden on the vegetation by using pine needles as a bio-indicator system and to deliberate on the possible role of TCA in the dynamics of the vegetation in southern Africa. Field experiments conducted on pine trees and on C3 and C4 crop plants under controlled laboratory conditions, have revealed that plants could be influenced positively or negatively by TCA. To obtain an integrated assessment of the pollution emission over a time span of at least one year, two-year-old pine needles of different Pinus species were used as a bio-indicator for TCA pollution at different measuring sites. The data of our investigation clearly indicate that areas exist in South Africa where the vegetation is burdened by ecotoxicologically relevant TCA contents comparable to those in central Europe and southern Russia where TCA was shown to play a role in the destabilisation of the steppe vegetation.

Trichloroacetic acid (TCA, CCl(3)COOH) has been associated with forest damage but the source of TCA to trees is poorly characterised. To investigate the routes and effects of TCA uptake in conifers, 120 Sitka spruce (Picea sitchensis (Bong.) Carr) saplings were exposed to control, 10 or 100 microg l(-1) solutions of TCA applied twice weekly to foliage only or soil only over two consecutive 5-month growing seasons. At the end of each growing season similar elevated TCA concentrations (approximate range 200-300 ng g(-1) dwt) were detected in both foliage and soil-dosed saplings exposed to 100 microg l(-1) TCA solutions showing that TCA uptake can occur from both exposure routes. Higher TCA concentrations in branchwood of foliage-dosed saplings suggest that atmospheric TCA in solution is taken up indirectly into conifer needles via branch and stemwood. TCA concentrations in needles declined slowly by only 25-30% over 6 months of winter without dosing. No effect of TCA exposure on sapling growth was measured during the experiment. However at the end of the first growing season needles of saplings exposed to 10 or 100 microg l(-1) foliage-applied TCA showed significantly more visible damage, higher activities of some detoxifying enzymes, lower protein contents and poorer water control than needles of saplings dosed with the same TCA concentrations to the soil. At the end of each growing season the combined TCA storage in needles, stemwood, branchwood and soil of each sapling was <6% of TCA applied. Even with an estimated half-life of tens of days for within-sapling elimination of TCA during the growing season, this indicates that TCA is eliminated rapidly before uptake or accumulates in another compartment. Although TCA stored in sapling needles accounted for only a small proportion of TCA stored in the sapling/soil system it appears to significantly affect some measures of sapling health.

Leptin is an adipose and liver tissue-derived secreted protein in chickens that has been implicated in the regulation of food intake and whole-body energy balance. In this study, the metabolic clearance and tissue uptake of leptin were examined in the chicken (Gallus gallus). Four-week-old broiler males were infused with (125)I-labeled mouse leptin. Chromatography of radiolabeled leptin in plasma produced two peaks, one at 16 kDa (free leptin) and a free iodine peak. No leptin binding protein in blood was detected. Leptin was cleared with a half-life estimate of 23 min. In order to investigate the tissue distribution and uptake of radiolabeled leptin, multiple tissues were removed from infused birds at 15 and 240 min post-infusion, and trichloroacetic acid (TCA)-precipitable radioactivity was determined. The amounts of radioactivity at 15 min post-infusion in the tissues in rank order were: kidney, testis, lung, spleen, heart, liver, small and large intestine, gizzard, pancreas, bursa, leg and breast muscle, adrenals, and brain. A slightly different pattern of distribution was observed at 240 min post-infusion. We conclude from these studies that unlike mammals, no circulating leptin binding protein is present in chickens. Leptin is metabolized and cleared very rapidly from blood by the kidney.

The concentrations and input/output fluxes of trichloroacetic acid (TCA) were measured in all relevant media for one year at a 0.86 km2 upland conifer plantation and moorland catchment in SW Scotland (n > 380 separate samples analyzed). Annual wet precipitation to the catchment was 2.5 and 0.4 m for rain and cloud, respectively. TCA input to the catchment for the year was 2100 g, predominantly in rainwater (86%), with additional input via cloudwater (13%) and gas plus particle dry deposition (1%). There were no seasonal trends in TCA deposition, and cloudwater concentration was not enhanced over rainwater. TCA in precipitation exceeded concentrations estimated using currently accepted routes of gas-phase oxidation from anthropogenic chlorinated hydrocarbon precursors, in agreement with previous studies. Export of TCA from the catchment in streamwater totalled 1970 g for the year of study. The TCA concentration in streamwater at outflow (median 1.2 microg L(-1)) was significantly greater than that before the stream had passed through the conifer plantation. To well-within measurement uncertainties, the catchment is currently at steady-state with respect to TCA input/output. The catchment reservoir of TCA was dominated by soils (approximately 90%), with the remainder distributed in forest litter (approximately 9%), forest branchwood and stemwood (approximately 0.7%), forest foliage (approximately 0.5%), and moorland foliage (approximately 0.1%). Although TCA is clearly taken up into foliage, which consequently may be important for the vegetation, this was a relatively minor process for TCA at the catchment scale. If it is assumed, on the basis of laboratory extraction experiments, that only approximately 20% of "whole soil" TCA measured in this work was water extractable, then total mass of TCA in the catchment is reduced from approximately 13 to approximately 3.5 kg. Comparing the latter value with the annual flux yields an average steady-state residence time for TCA in the catchment of approximately 1-2 y, if all TCA is involved in catchment turnover. Considering that other evidence indicates the lifetime of TCA in soil and biota is considerably shorter than this (weeks rather than years), the magnitude of the TCA reservoir is suggested to be strong evidence for net natural TCA production in soils and/or that the majority of TCA in the reservoir is not involved with external fluxes.

Oxidative stress is supposed to play an important role in demyelinating diseases. Oligodendrocytes are the myelin-forming cells in the brain and are highly susceptible to oxidative stress due to their low antioxidative defense systems and high metabolic rate. In the present work, we tested the response of the oligodendrocyte cell line OLN 93 to oxidative stress. OLN 93 cell cultures are characterized by a loss of cell viability after oxidation. This loss of cell viability is accompanied by an increase in protein oxidation and consequently an elevated overall proteolysis. To minimize the oxidative damage, we tested the effects of the antioxidants alpha-lipoic acid and coenzyme Q(10). Both compounds were able to elevate cell viability and to decrease intracellular protein turnover and oxidant induced protein oxidation. Therefore, we concluded that the excessive oxidative damage of oligodendrocytes and their protein pool can be prevented by the usage of antioxidants.

Soils have been shown to possess a strong microbial trichloroacetic acid (TCA)-degrading activity. High TCA-degradation rate was also observed during soil extraction with water. For correct measurements of TCA levels in soil all TCA-degrading activities have to be inhibited immediately after sampling before analysis. We used rapid freezing of soil samples (optimally in liquid nitrogen) with subsequent storage and slow thawing before analysis as an efficient technique for suppressing the degradation. Frozen soil samples stored overnight at -20 degrees C and then thawed slowly exhibited very low residual TCA-degrading activity for several hours. Omitting the above procedure could lead to the confusing differences between the TCA levels previously reported in the literature.

This paper reviews the concentrations of trichloroacetate (TCA) in the atmosphere-plant-soil system. Data originate mainly from Europe. The median TCA concentration in rainwater and canopy drip decreased until 1995. From then the median TCA concentration in rainwater remains rather constant while for canopy drip later data are not available. The same seems to hold for concentrations in air although a very limited data set is available. The median concentrations in coniferous needles and groundwater are constant for the period observed. The median TCA concentrations in soil decreased until 1992 and then remained constant.The TCA formation from chlorinated solvents in the atmosphere may explain a substantial percentage of the TCA amount in the atmosphere. The TCA concentrations in rainwater and canopy drip indicate that there will be other sources contributing to 10-50%. Waste incineration, biomass burning and natural formation in the marine boundary layer are potential candidate sources of TCA, but nothing can be said as yet on their TCA emission rates. Anthropogenic emissions of chlorine could also be a source.TCA can be formed from chlorinated solvents by biota. However, for coniferous trees the uptake of TCA from soil may be the predominant route. Biotic and abiotic reactions can cause to formation of TCA in soil, but also formation of TCA from chlorinated solvents by biota that excrete TCA, may contribute. Mass balance calculations of the bioactive soil top layer show that the production rate of TCA in certain soil types could be substantial. The mass balance calculations could not distinguish between natural and anthropogenic sources in soil.

Trichloroacetic acid (TCA, CCl(3)COOH) is a phytotoxic chemical. Although TCA salts and derivates were once used as herbicides to combat perennial grasses and weeds, they have since been banned because of their indiscriminate herbicidal effects on woody plant species. However, TCA can also be formed in the atmosphere. For instance, the high-volatile C(2)-chlorohydrocarbons tetrachloroethene (TECE, C(2)Cl(4)) and 1,1,1-trichloroethane (TCE, CCl(3)CH(3)) can react under oxidative conditions in the atmosphere to form TCA and other substances. The ongoing industrialisation of Southeast Asia, South Africa and South America means that use of TECE as solvents in the metal and textile industries of these regions in the southern hemisphere can be expected to rise. The increasing emissions of this substance--together with the rise in the atmospheric oxidation potential caused by urban activities, slash and burn agriculture and forest fires in the southern hemisphere--could lead to a greater input/formation of TCA in the vegetation located in the lee of these emission sources. By means of biomonitoring studies, the input/formation of TCA in vegetation was detected at various locations in South America, North America, Africa, and Europe.

Trichloroacetic acid (TCA), in former times used as a herbicide in agriculture, is now ubiquitous and almost evenly distributed in precipitations of the Northern and Southern Hemisphere, despite larger emissions of the possible precursors tetrachloroethene and 1,1,1-trichloroethane in the Northern Hemisphere. The permanent input of a herbicidal compound into most vulnerable ecosystems might lead to adverse effects to biota (plants, microorganisms, etc.). TCA soil levels of coniferous forests in mountainous regions of Central Europe are significantly elevated. Mass balance calculations show that precipitation as sole source of TCA in soil seems to be of minor importance and provide evidence for a natural formation of TCA within soil itself. In addition, the isolation of a chlorinating enzyme in soil and laboratory experiments with humic acid, iron and halide point to an omnipresent chlorinating capability of nature producing polyhalogenated organic compounds such as TCA. In this paper we present an overview of TCA levels in the environment and provide a new estimate about the extent of a natural TCA formation, especially in soil.

In environmental risk assessments the question has to be answered, whether risk reduction measures are necessary in order to protect the environment. If the combination of natural and anthropogenic sources of a chemical substance leads to an unacceptable risk, the man-made emissions have to be reduced. In this case the proportions of the anthropogenic and natural emissions have to be quantified. Difficulties and possible solutions are discussed in the scope of the OECD- and EU-risk assessments of trichloroacetic acid (TCA) and tetrachloroethylene. In the atmosphere, TCA is formed by photo-oxidative degradation of tetrachloroethylene (PER) and 1,1,1-trichloroethane. The available data on atmospheric chemistry indicate that tetrachloroethylene is the more important pre-cursor. With its high water solubility and low volatility, TCA is adsorbed onto aerosol particles and precipitated during rainfalls. Extended monitoring in rainwater confirmed the global distribution of airborne TCA. TCA reaches soils by dry and wet deposition. In addition formation of TCA from tetrachloroethylene in plants was observed. Consequently, high concentrations were detected in needles, leaves and in forest soil especially in mountain regions. The effect assessment revealed that plants exposed via soil are the most sensitive species compared to other terrestrial organisms. A PNECsoil of 2.4 microg/kg dw was derived from a long-term study with pine and spruce seedlings. When this PNEC is compared with the measured concentrations of TCA in soil, in certain regions a PEC/PNEC ratio >1 is obtained. This clearly indicates a risk to the terrestrial ecosystem, with the consequence that risk reduction measures are deemed necessary. To quantify the causes of the high levels of TCA in certain soils, and to investigate the geographical extent of the problem, intensive and widespread monitoring of soil, air and rainwater for TCA and tetrachloroethylene would be necessary to be able to perform a full mass balance study at an appropriate number of sites. In addition, measurements of the 14C content in TCA isolated from soil could clarify whether a significant proportion of the TCA occurs from natural sources. The possible formation of TCA in soil can also be tested by incubation of isotope enriched inorganic chloride with subsequent mass spectrometry of TCA.

The first long-term concurrent measurements of trichloroacetic acid (TCA) in rainwater, in cloudwater, and in air (both gas and particle phase) are reported. Measurements were made weekly between June 1998 and April 2000 at a rural forested upland site in SE Scotland. Rainwater TCA concentration did not differ significantly between two elevations (602 and 275 m asl), with precipitation-weighted mean values of 0.77 and 0.70 microg L(-1), respectively (n > 75). The precipitation-weighted mean concentration of TCA in cloudwater at the highest elevation was 0.92 microg L(-1), yielding an average cloudwater enrichment factor of 1.2, considerably lower than for other inorganic ions measured. Rainwater and cloudwater TCA concentrations did not vary systematically with season. Since wet precipitation depth also did not vary systematically with season, the wet deposition fluxes of TCA were likewise invariant (annual fluxes at the highest elevation of 880 and 130 microg m(-2), respectively, for rain and cloud interception to spruce forest). Weekly integrated concentrations of TCA in air (gas and particle) were very low (median 25 pg m(-3), range < LOD-110 pg m(-3)). The estimated upper limit for annual dry deposition of TCA at this site was approximately 20 microg m(-2), assuming a deposition velocity of 2 cm s(-1). Concentrations of TCA in air correlated reasonably strongly with concentrations in rainwater, with a partition ratio approximately equal to the Henry's law coefficient. On average, only about 23% of TCA measured in Edinburgh air was associated with the particle phase. These measurements are consistent with the observed high scavenging ratio of TCA (ratio of concentration in air to concentration in rainwater). Overall, these data confirm that the atmosphere is an important source of TCA to the environment and that precipitation is the dominant transfer mechanism. In line with previous work, the atmospheric deposition flux is greater than expected from the current understanding of atmospheric production of TCA from anthropogenic precursors. It is suggested that aqueous-phase processes could lead to greater atmospheric conversion of chlorinated solvent precursors to TCA than is currently accepted.

A new and simple approach is described for the determination of the haloacetic acids (such as mono-, di- and trichloroacetic acids) usually found in drinking water as chlorination by-products after disinfection processes and acetic acid. The new approach, termed vacancy ion-exclusion chromatography, is based on an ion-exclusion mechanism but using the sample solution as the mobile phase, pure water as the injected sample, and a weakly acidic cation-exchange resin column (TSKgel OApak-A) as the stationary phase. The addition of sulfuric acid to the mobile phase results in highly sensitive conductivity detection with sharp and well-shaped peaks, leading to excellent and efficient separations. The elution order was sulfuric acid, dichloroacetic acid, monochloroacetic acid, trichloroacetic acid, and acetic acid. The separation of these acids depends on their pKa values. Acids with lower pKa values were eluted earlier than those with higher pKa, except for trichloroacetic acid due to a hydrophobic-adsorption effect occurring as a side-effect of vacancy ion-exclusion chromatography. The detection limits of these acids in the present study with conductivity detection were 3.4 microM for monochloroacetic acid, 0.86 microM for dichloroacetic acid and 0.15 microM for trichloroacetic acid.

Trichloroacetic acid (TCA) and dichloroacetic acid (DCA) are possible minor atmospheric degradation products of perchloroethylene and trichloroethylene, respectively. These acids may be wet- or dry-deposited from the atmosphere to land surfaces and hence possibly affect plant growth. However, the existing database on TCA levels in soil is limited to a few studies carried out in the late 1980's and the early to mid-1990's and it was concluded that there is a need for further measurements of concentrations of TCA and DCA in soils. In this study soil samples from 10 locations in 5 European countries, as well as vegetation samples, and a limited number of rainwater and air samples were collected and analysed for DCA and TCA to determine the concentrations of these compounds. An isotope dilution method using GC-MS was used for the determination of these acids in the samples. The method was briefly validated and the performance characteristics are presented. The results of the analysis of the soil samples show that the DCA and TCA concentrations in soil from different sites in Europe are more or less comparable, with the exception of Germany, especially Freudenstadt, where significantly higher TCA concentrations (up to 12 microg kg(-1) dw) were found. The average DCA and TCA concentrations in soil in this study were 0.25 +/- 0.12 and 0.64 +/- 1.40 microg kg(-1) dw, respectively. Generally, the concentration in soils from forest areas are about twice those from open-land areas. The DCA and TCA concentrations in vegetation samples ranged from 2.1 to 73 microg kg(-1) dw for DCA and from 4.7 to 17 microg kg(-1) dw for TCA. Thus, the concentrations in vegetation samples are 10-20 times higher than the soil concentrations. DCA and TCA concentrations in wet deposition samples and air samples collected in The Netherlands were 0.14 and 0.15 microg l(-1) for wet deposition samples and <0.5 and 0.7 ng m(-3) for air samples respectively. For these samples taken in The Netherlands, the estimated values for soil and air concentrations calculated from the wet deposition concentrations are in agreement with the concentrations measured in this study.

This study reports an example of visible-light photocatalyst based on TiO2 modified by ruthenium-complex sensitizers and noble metal deposits. The photodegradation of trichloroacetate (TCA) and carbon tetrachloride was used as a probe reaction for evaluating the visible light activity of the photocatalyst under the illumination of lambda > 420 nm. Photodeposition of platinum nanoparticles on dye-sensitized TiO2 (Pt/TiO2/Ru(II)L3) drastically enhanced the degradation rate of TCA and CCl4. The visible light reactivity of Pt/TiO2/Ru(II)L3 was optimal with [Ru(II)L3] = 10 microM, [TiO2] = 0.5 g/L, and Pt loading of about 0.2 wt %. Although no electron donors to regenerate the oxidized Ru-sensitizers were added in the aqueous suspension, the photoreductive dechlorination of perchlorinated compounds proceeded far beyond the stoichiometric limit of the initial sensitizer concentration. Water acted as an electron donor to regenerate the sensitizer with a concurrent production of dioxygen. On the other hand, Pt/TiO2/Ru(II)L3 was completely inactive in the presence of dissolved oxygen and the in-situ generated dioxygen gradually decelerated the dechlorination rate. Conduction band electrons transferred to O2 in preference to CCl4 and TCA on Pt deposits. Other noble metals (Ag, Au, and Pd) deposited on TiO2 showed a better oxygen-tolerance but less visible-light reactivity than PtTiO2/Ru(II)L3. Effects of metal loading on the visible light activity and its implications for the efficientvisible-light photocatalyst development are discussed.

Suppositions that the trichloroacetic acid (TCA, CCl3C(O)OH) found in nature was a consequence solely of the use of chlorinated hydrocarbon solvents prompted this critical review of the literature on its environmental fluxes and occurrences. TCA is widely distributed in forest soils (where it was rarely used as an herbicide) and measurements suggest a soil flux of 160 000 tonnes yr(-1) in European forests alone. TCA is also produced during oxidative water treatment and the global flux could amount to 55 000 tonnes yr(-1) (from pulp and paper manufacture, potable water and cooling water treatments). By contrast, the yields of TCA from chlorinated hydrocarbon solvents are small: from tetrachloroethene 13 600 tonnes yr(-1) and from 1,1,1-trichloroethane 4300 tonnes yr(-1) on a global basis, at the atmospheric burdens and removal rates typical of the late 1990s. TCA is ubiquitous in rainwater and snow. Its concentrations are highly variable and the variations cannot be connected with location or date. However, there is no significant difference between the concentrations found in Chile and in eastern Canada (by the same analysts), or between Malawi and western Canada, or between Antarctica and Switzerland, nor any significant difference globally between the concentrations in cloud, rain and snow (although local enhancement in fog water has been shown). TCA is present in old ice and firn. At the deepest levels, the firn was deposited early in the 19th century, well before the possibility of contamination by industrial production of reactive chlorine, implying a non-industrial background. This proposition is supported by plume measurements from pulp mills in Finland. TCA is ubiquitous in soils; concentrations are very variable but there are some indications that soils under coniferous trees contain higher amounts. The concentrations of TCA found in plant tissue are region-specific and may also be plant-specific, to the extent that conifers seem to contain more than other species. TCA is removed from the environment naturally. There is abundant evidence that soil microorganisms dehalogenate TCA and it is lost from within spruce needles with a half-life of 10 days. There is also recent evidence of an abiotic aqueous decarboxylation mechanism with a half-life of 22 days. The supposedly widespread effects of TCA in conifer needles are not shown in controlled experiments. At concentrations in the needles of Scots pine similar to those observed in needles in forest trees, changes consequent on TCA treatment of field laboratory specimens were almost all insignificant.

To investigate the role of trichloro compounds as a potential cause of "cork taint" in wine, an assay for trichloroanisole (TCA) and trichlorophenol (TCP) in corks and wine was developed utilizing solid phase extraction on a C(18) cartridge followed by gas chromatography with mass selective detection. Recovery and imprecision for TCA were 86-102 and 1.6-5.8%, respectively, and for TCP 82-103% and 1.7-3.9%, respectively. Limits of detection and quantitation were 0.1 and 2 ng/L, respectively, for TCA, and 0.7 and 4 ng/L, respectively for TCP. A survey of 2400 commercial wines revealed a higher incidence of cork taint in white wine than in red and in wines utilizing composite cork closures; wines from central Europe and Spain had higher overall rates of contamination and those from Canada and Italy the lowest. Significant but modest associations were found between the TCA and TCP contents of the wines and corks, but many wines exhibiting cork taint had low or undetectable concentrations of TCA. Over a 12-month period, experimentally bottled wines exhibited a slow increase in TCA and TCP content while cork closures manifested a decrease; most bottles showing cork taint contained low levels of TCA, and TCP concentrations were well below the sensory threshold. Neither compound was cytotoxic to human cell lines in culture up to final concentrations of 500 ng/mL. It was concluded that these two trichloro compounds are, at most, minor components of cork taint in commercial wines.

A simple, closed-form analytical expression based on the homogenous solution diffusion model is derived for contaminant removal during nanofiltration (NF) of ground and surface water. Solute permeation and back-diffusion coefficients were used as fitting parameters to model rejection characteristics of four thin-film composite NF membranes under conditions typical of drinking water NF. Nonlinear fits of the model to experimental data suggests that the United States Environmental Protection Agency's (USEPA)'s Information Collection Rule protocol for bench-scale studies could be improved to obtain greater precision of the mass transfer coefficients. The model was found to fit rejection data for several water treatment contaminants including total organic carbon, precursors to total organic halide, four trihalomethanes and nine haloacetic acids containing chlorine and bromine, calcium and total hardness, alkalinity and conductivity. The simplified approach to mass transfer calculations from multisolute systems suggests that feed water recovery has a stronger influence on contaminant rejection than permeate flux. Evidence for coupled transport of divalent inorganic ions is also presented. Even though the model developed does not account for ion coupling and cannot be applied in a purely predictive mode, it can assist in the better design and interpretation of data obtained from site-specific pilot-scale water treatment NF studies conducted in support of plant design.

Trichloroacetic acid (TCAA) is a phytotoxic chemical, present throughout the environment. The majority of methods for analysis of TCAA require chemical derivatisation and multiple extraction steps prior to analysis by gas-chromatography. Here, a new analytical method for TCAA determination in environmental matrices is reported. The method is based on a modified Nielsen-Kryger steam distillation that combines into one 1 h reflux the thermal decarboxylation of TCAA to CHCl3 and the partitioning and concentration of the CHCl3 into 5 ml of hexane, which is analysed by GC. Sample preparation is minimal and no matrix standard additions are required. The background CHCl3 in the sample is removed prior to extraction by degassing the solution for 1 h with nitrogen. Optimisation of the method gave recoveries from three separate solutions of 0.31 ppb aqueous TCAA standards of 93 +/- 15% (n = 9), 110 +/- 9% (n = 9) and 105 +/- 11% (n = 6). The extraction method has been compared with a decarboxylation and headspace GC method for determination of TCAA in Sitka spruce needles. No significant difference in TCAA concentration or replicate precision between the two methods was observed.

An extraction technique using MTBE (methyl tert. butyl ether) and reagent water in combination with ion chromatography and conductivity determination was developed to quantify dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) concentrations in raw water after chlorination. The detection limit of the method was 0.45 and 1.50 microg/L for DCAA and TCAA, respectively. Mean values of recovery ranged from 90 to 96% for DCAA and 95 to 108% for TCAA. The evaluation of recovery and precision of the method indicates that the performance characteristics are comparable with gas chromatographic (GC) methods reported in literature. In addition, the procedure is simple, fast, and does not need any derivatization step. Application of the analytical method to the determination of DCAA and TCAA in real samples is shown.

We describe a simple, precise, and sensitive assay of tetrachloroethylene and trichloroethylene in tissues, suitable both for emergency cases and forensic medicine. The method employs headspace solid phase microextraction-capillary gas chromatography and electron capture detection. The case is relative to a 45-year-old woman discovered unconscious in a laundry area. The concentrations of the solvents in tissues were determined and compared to other previously published fatalities.

Headspace solid-phase microextraction (SPME) was studied as a possible alternative to liquid-liquid extraction for the analysis of haloacetic acids (HAAs) in water. The method involves derivatization of the acids to their ethyl esters using sulphuric acid and ethanol after evaporation, followed by headspace SPME with a polydimethylsiloxane fibre and gas chromatography-ion trap mass spectrometry (GC-IT-MS). The derivatization procedure was optimized: maximum sensitivity was obtained with esterification for 10 min at 50 degrees C in 30 microl of sulphuric acid and 40 microl of ethanol. The headspace SPME conditions were also optimized and good sensitivity was obtained at a sampling temperature of 25 degrees C, an absorption time of 10 min, the addition of 0.1 g of anhydrous sodium sulfate and a desorption time of 2 min. Good precision (RSD lower than 10%) and detection limits in the ng l(-1) range (from 10 to 200 ng l(-1)) were obtained for all the compounds. The optimized procedure was applied to the analysis of HAAs in tap water and the results obtained by standard addition agreed with those of EPA method 552.2, whereas discrepancies due to matrix interferences were observed using external calibration. Consequently, headspace SPME-GC-IT-MS with standard addition is recommended for the analysis of these compounds in drinking water.

The microextraction/ion chromatographic (IC) method developed in this study involves extraction of 9 haloacetic acids (HAAs) from aqueous samples (acidified with sulfuric acid to a pH of < 0.5 and amended with copper sulfate pentahydrate and sodium sulfate) with methyl tert-butyl ether (MTBE), back extraction into reagent water, and analysis by IC with conductivity detection. The separation column consists of an Ion Pac AG-11 (2 mm id x 50 mm length) guard column and an Ion Pac AS-11 (2 mm id x 250 mm length) analytical column, and the concentration column is a 4 mm id x 35 mm length Dionex TAC-LP column. Use of the 2 mm id Dionex AS-11 column improved detection limits especially for trichloracetic acid (TCAA), bromodichloroacetic acid (BDCAA), dibromochloroacetic acid (DBCAA), and tribromoacetic acid (TBAA). The peak interfering with BCAA elutes at the same retention time as nitrate; however, we have not confirmed the presence of nitrate. Stability studies indicate that HAAs are stable in water for at least 8 days when preserved with ammonium chloride at 100 mg/L and stored at 4 degrees C in the dark. At day 30, recoveries were still high (e.g., 92.1-106%) for dichloroacetic acid (DCAA), BCAA, dibromoacetic acid (DBAA), trichloroacetic acid (TCAA), BDCAA, and DBCAA. However, recoveries of monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), and TBAA were only 54.6, 56.8, and 66.8%, respectively. Stability studies of HAAs in H2SO4-saturated MTBE indicate that all compounds except TBAA are stable for 48 h when stored at 4 degrees C in the dark. TBAA recoveries dropped to 47.1% after 6 h of storage and no TBAA was detected after 48 h of storage. The method described here is only preliminary and was tested in only one laboratory. Additional research is needed to improve method performance.

This study compares four different commercial sorbents, LC-SAX (a quaternary ammonium anion exchanger), LiChrolut EN (a highly crosslinked styrene-divinylbenzene), Envi-Carb (a graphitized carbon black) and Oasis HLB [a macroporous poly(divinylbenzene-co-N-vinylpyrrolidone) copolymer], for the solid-phase extraction (SPE) of various haloacetic compounds from aqueous samples. The recoveries with the different sorbents were studied by coupling an off-line SPE system to capillary electrophoresis with indirect photometric detection. The recoveries were highest when LiChrolut EN was used. The limits of detection for the compounds are in the low microgram per litre range and the recovery values are over 80% for dichloroacetic acid and trichloroacetic acid, two of the most habitual haloacetic acids in chlorinated water, when 500 ml of standard solution was preconcentrated using this sorbent. Finally, the performance of the method with different water samples, the effect of chlorination in a treatment plant and the evolution of the haloacetic acids in the water distribution system were tested and the results were compared with those obtained using liquid-liquid extraction and gas chromatography-mass spectrometry.

Trichloroacetic acid (TCA) and dichloroacetic acid (DCA) are environmental contaminants that are suspected human carcinogens. To obtain more detail on the role of the liver in the kinetics of TCA and DCA, experimental studies in the isolated perfused rat liver (IPRL) system were conducted. The IPRL system was dosed with either 5 or 50 micromol of either TCA or DCA (25 or 250 microM initial concentration, respectively). TCA and DCA concentrations were followed in perfusion medium and bile for 2 h. The chemical concentration in liver was determined at the end of exposure. Liver viability was monitored by measuring leakage of lactate dehydrogenase (LDH) into perfusion medium and the rate of bile production. Studies performed with TCA showed that the total TCA concentration in perfusion medium decreased slightly during the first 30 min of exposure and remained constant thereafter. Most TCA, greater than 90% of total, was bound to albumin in the perfusion medium. A low, linear excretion rate of TCA in bile was obtained. The calculated free TCA concentration in the liver intracellular water space was higher than the unbound TCA concentration in the perfusion medium. Parallel studies with DCA showed that the DCA concentration in perfusion medium decreased rapidly. Of the total DCA in the perfusion medium, 60% was bound to albumin. The concentration of DCA in bile decreased over time. There was no DCA detectable in the liver after 2 h of exposure at both DCA concentrations. Enzyme leakage and bile production did not change in the presence of TCA or DCA, indicating that these concentrations were not acutely cytotoxic to the liver., (Copyright 1998 Academic Press.)

A capillary zone electrophoresis (CZE) system for determining haloacetic acids in water was optimized with indirect photometric detection. Two different carrier electrolytes, potassium hydrogenphthalate and sodium 2,6-naphthalenedicarboxylate, were evaluated in terms of sensitivity and two different electroosmotic flow modifiers, tetradecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide, were tested. Parameters such as electrolyte concentration and pH, and the concentration of the electroosmotic flow modifiers, which affect the CZE separations, were investigated. The method was used to determine haloacetic acids in chlorine tap water using the liquid-liquid extraction process.

Trichloroacetic acid (TCA) is a metabolite of trichloroethylene (TRI) thought to contribute to its hepatocarcinogenic effects in mice. Recent studies have shown that peak blood concentrations of TCA do not occur until approximately 12 hr after an oral dose of TRI; however, blood concentrations of TRI reach a maximum within 1 hr and is nondetectable after 2 hr. The objective of this study was to examine quantitatively enterohepatic recirculation of trichloroethanol (TCEOH) and TCA as a possible mechanism responsible for the delayed production of TCA. Jugular vein, duodenum, and bile duct-cannulated Fischer 344 rats were used, with the collection of blood, bile, urine, and feces samples after intraduodenal and intravenous dosing of animals with TRI, TCEOH, and TCA. Samples were analyzed by GC for TCA, total TCEOH, and free TCEOH. The results show that, after an intravenous dose of TCEOH (100 mg/kg), 36% of the TCEOH in blood is attributable to enterohepatic recirculation. With the same treatment, 76% of the TCA in blood is attributable to enterohepatic recirculation of metabolites. Peak concentrations of total TCEOH in bile, after an intraduodenal dose of TRI, are over 5 times higher than peak concentrations of total TCEOH in systemic blood. Peak concentrations of TCEOH glucuronide in bile are approximately 200 times higher than peak concentrations of TCEOH glucuronide in systemic blood.

Background: Chemical peeling using trichloroacetic acid (TCA) is a popular and long utilized procedure in dermatology and cosmetic surgery., Objective: To determine the actual concentration of TCA in four disparate methods of preparation of solutions, expressed in the standard pharmaceutical method of weight to volume (wt/vol)., Methods: Method I was wt/vol, method II was weight to weight (wt/wt), method III was grams of TCA added to 100 cc water, and method IV was the usage of saturated TCA, and calling it 100%, then making appropriate dilutions. The amounts of TCA in each solution for methods II, III, and IV were converted, by calculation, to the wt/vol method., Results: The relative concentrations of TCA, ranked by the wt/vol pharmaceutical standard, showed that from strongest to weakest: method IV > method II > method I > method III., Conclusions: Tremendous variations were found in the relative concentrations of TCA in these solutions. To avoid mishaps and complications, the wt/vol method should be used.

Capillary gas chromatography with electron capture detection is described for the quantification of chloral hydrate (CH) and is metabolites trichloroethanol (TCE) and trichloroacetic acid (TCA) in 0.1-1 mL of plasma samples. The method, with 2,2'-dichloroethanol (DCE) as internal standard, involved extraction of chloral hydrate and trichloroethanol with diethyl ether and methylation of trichloroacetic acid with 3-methyl-1-tolyltriazene (MTT), followed by diethyl ether extraction. The method has a detection limit of 5 ng/mL for CH and TCE and 10 ng/mL for TCA and also allows the determination of TCE-glucuronide in 0.1-1 mL of plasma samples. It exhibits good linearity and precision. The method was applied to samples of plasma from a neonate after a single dose of 40 mg/kg of chloral hydrate and from an adult after a single dose of 6.25 mg/kg.

18 different swimming pool waters in the Bonn-Rhein-Sieg area were analysed for trihalogenmethanes, halogenated acetic acids, 2,2-dichloropropionic acid, dihalogenacetonitriles and chloral hydrate. Most substances mentioned above were determined in almost every sample reaching total concentrations up to 538 micrograms/l. Considering the results one can see that some of the main pollutants are polar organic compounds like di- and trichloroacetic acid as well as chloral hydrate.

We studied 31 employees (26 men, five women) from three firms, between the ages of 16 and 56 years, who had been exposed to trichloroethylene (TRI) from 1 month to 35 years, mean 7 years. To objectify the actual solvent-exposure we performed "biological monitoring" and determined TRI- and the metabolites trichloroethanol (TCE) and trichloroacetic acid (TCA) in blood- and/or urine-samples. The following concentrations were found in the urine-samples: TCE 19.0-357.0 mg/g creatinine, median 90.0; TCA 2.0-201.0 mg/g creatinine, median 48.0; TTC (TCE + TCA) 31.0-416.0 mg/g creatinine, median 112.5. Additionally three results of former urine-analyses in the period 1978-1980 from 10 workers were obtained to calculate "time-weighted-average (TWA)"-levels (TWA-TTC in urine: 53-640 mg/g creatinine). Nerve conduction velocity (NLG)-measurements of motor and/or sensory fibers of the ulnar and median nerve were performed to test peripheral nerve function. Seven employees were excluded. They had possible competitive risks of peripheral neuropathy, or were of less than 10 months exposed. For controls we examined 24 healthy persons of identical sex and age (matched pairs), but without known risks of a peripheral neuropathy. In comparing the nerve conduction velocities there were no significant differences between TRI-exposed and non-exposed persons. Correlation analyses and the individual assessment of the data concerning exposure/dose and effect revealed no signs of a "dose-effect-relationship".

A method for the detection of ascorbic acid using high-performance liquid chromatography with coulometric electrochemical detection and a technique for stabilization of the vitamin are described. Since less than 1 pmol of ascorbic acid can be detected, this assay provides significantly greater sensitivity than nearly all of the currently available procedures. Stabilization of 10 pmol or less of ascorbic acid at room temperature for up to 4 h and for several weeks at -70 degrees C facilitates storage of a large number of samples and measurement of ascorbic acid using an automated sampling device. This method was used to quantitate the amounts of ascorbic acid in human polymorphonuclear leukocytes and bovine adrenomedullary chromaffin granules. The calculated concentrations found for human neutrophils (1.35 mM) and bovine chromaffin granules (10.0 mM) are in agreement with previously published data. The assay is suitable for the determination of ascorbic acid in biological samples where only a small amount of tissue is available or very low amounts of ascorbic acid are found. This method is the first application of coulometric electrochemical detection to ascorbic acid HPLC analysis.

Four colostomated hybrid laying hens were fed, for 6 days, a semisynthetic ration containing 15N labelled casein as sole protein source. Within this period, the hens laid 13 eggs which were fractionated into egg yolk, egg white and egg shell. The N content of these egg fractions was established. A TCE soluble and TCE precipitable fraction (TCE=trichloroacetic acid) were obtained from the fractions of egg yolk and egg white. Additionally, an analysis was made of the set of amino acids contained in the crude protein of the egg yolk, egg white and egg membrane (lysine, histidine and arginine only). The excess 15N atom% (15N') was established in the crude protein, in the nitrogen from the TCE soluble and TCE precipitable fractions and in the N from 17 amino acids of the egg yold and egg white. In the egg membrane fraction the 15N' atom% was determined as percentage of the total amount of N and of the amount of N contained in the basic amino acids. Essential differences between the 3 egg fractions were noticed with regard to the process of initial incorporation of labelled N and the intensity of this process after the onset of 15N application. 15N' was detected in the egg shell as early as 4 hrs after administration of the 15N' dose. Heavy nitrogen was found to be contained in the egg white of eggs that were laid on the 2nd day of experiment. The level of 15N' atom% in the egg white increased essentially during the following days of experiment; the 15N'quantities in the egg white were considerably higher than those in the egg yolk. Similar results were obtained for the process of 15N incorporation into the 17 amino acids. It is assumed that differences between the 3 fractions as observed in the level of labelling and in the pattern of 15N' incorporation are accounted for by the different sites and different times of protein synthesis for the different egg proteins.