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PubMed1981

Determination of pentachlorophenol and related compounds in animal materials by high-performance liquid chromatography and gas chromatography.

The rapid determination of pentachlorophenol and tetrachlorophenols in animal materials by high-performance liquid chromatography (HPLC) on porous silica is described. Non-fatty substrates are digested in alkali and the chlorophenols extracted as ion pairs. Fatty materials are extracted with ethyl acetate-hexane after acidification. Extracts are cleaned up on "Sep-Pak" silica or Florisil cartridges. Penta- and tetrachloroanisoles are recovered by the extraction procedures and can be determined by gas chromatography if required. Mean recoveries of the chlorophenols were 73-108% at fortification levels of 0.1-10 mg/kg. A concentration of 0.1 mg/kg can readily be determined and the method can be adapted to reach about 1 microgram/kg. Identities can be confirmed by ion-pair HPLC on a reversed-phase column.

Animals↗
PubMed2002

Nonionic surfactant effects on pentachlorophenol biodegradation.

Several potential mechanisms of surfactant-induced inhibition of pentachlorophenol (PCP) biodegradation were tested using a pure bacterial culture of Sphingomonas chlorophenolicum sp. Strain RA2. PCP degradation, glucose degradation, and oxygen uptake during endogenous conditions and during glucose degradation were measured for batch systems in the presence of the nonionic surfactant Tergitol NP-10 (TNP10). TNP10 did not exert toxicity on RA2 as measured by dissolved oxygen uptake rates under endogenous conditions and glucose biodegradation rates. TNPIO reduced the substrate inhibition effect of PCP at high PCP concentrations, resulting in faster PCP degradation rates at higher concentrations of TNP10. Calculations of a micelle partition coefficient (Kmic) show that PCP degradation rates in the presence of surfactant can be explained by accounting for the amount of PCP available to the cell in the aqueous solution. A model is discussed based on these results where PCP is sequestered into micelles at high TNP10 concentrations to become less available to the bacterial cell and resulting in observed inhibition. Under substrate toxicity conditions, the same mechanism serves to increase the rate of PCP biodegradation by reducing aqueous PCP concentrations to less toxic levels.

Biodegradation, Environmental↗
PubMed2002

Degradation of pentachlorophenol by ozonation and biodegradability of intermediates.

The degradation pathway of pentachlorophenol (PCP) under ozonation and the biodegradability of the resulting intermediates were investigated. The objectives were to: (1) provide mechanistic details in the ozone-mediated degradation, (2) evaluate the biodegradability of resultant intermediates at various progressive stages of ozonation, and (3) thereby, assess the feasibility for a coupled chemical-biological treatment scheme for PCP. Tests of BOD5, COD, and E. coli toxicity along with qualitative and quantitative GC analyses were performed for aliquots withdrawn before and after various stages of ozonation and biological incubation. Ozonated PCP decomposed under the direct nucleophilic attack of ozone through an addition-elimination mechanism, resulting in tetrachloro-p-benzoquinone and tetrachloro-p-hydroquinone intermediates that were further degraded by O3 and OH* to other open-ring products including ketones and acids that eventually led to simple oxalic acid and quantitative release of chloride ion. As ozonation progressed toward but prior to complete mineralization, reaction intermediates became increasingly more biodegradable prior to complete degradation, which suggested the potential of using ozonation in conjunction with biological treatment for the effective control of chlorinated aromatics.

Biodegradation, Environmental↗
PubMed2003

Equilibrium partitioning of a non-ionic surfactant and pentachlorophenol between water and a non-aqueous phase liquid.

The partitioning of the non-ionic surfactant Tergitol NP-10 (TNP10) and pentachlorophenol (PCP) into a mineral oil light non-aqueous phase liquid (NAPL) were quantified in batch tests. Due to the ionizable nature of PCP, the effects of pH and ionic strength (micro) on the equilibrium partitioning were evaluated. NAPL:water partition coefficients (K(n:w)) of TNP10 ranged from 3 to 7 l(water)/l(NAPL). Enhanced PCP dissolution into water from the NAPL was achieved at aqueous TNP10 concentrations > or =200mg/l. Surfactant addition of 1200 mg/l TNP10 increased the aqueous PCP concentrations by 14-fold at pH 5 versus 2 to 3-fold at pH 7 as compared to PCP aqueous solubility. The more significant response at the lower pH is likely due to the greater hydrophobicity of PCP at the lower pH, which is approaching PCP's pK(a) of 4.7. Higher ionic strength (micro 0.11 versus 0.001 M) increased K(n:w) of PCP by 10-33% without surfactant, compared to a more than 150% increase with a dose of 4000 mg/l TNP10. This work contributes information relevant to the application of surfactants to remediate sites contaminated with NAPLs.

Environmental Pollution↗
PubMed2001

Synergistic cytotoxicity between pentachlorophenol and copper in a bacterial model.

Both pentachlorophenol (PCP) and copper compounds have been widely used as wood preservatives, and are commonly found not only in the area near wood-preserving facilities, but also in body fluids and tissues of people who are not occupationally exposed to them. In this study, we found that exposing bacteria to a combination of PCP and copper at non- or sub-toxic concentrations resulted in enhanced cytotoxic effect in a synergistic mode as indicated by both the inhibition of growth and the lowering of the colony-forming ability. The toxicity of the combination PCP/Cu(II) was relieved by hydrophilic chelating agents, thiol compounds and adventitious proteins, but was markedly potentiated by low levels of the lipophilic metal chelating agents.

Chelating Agents↗
PubMed2002

Phototransformation of polychlorinated dibenzo-p-dioxins from photolysis of pentachlorophenol on soils surface.

The phototransformation of polychlorinated dibenzo-p-dioxins (PCDDs) by photolysis of pentachlorophenol (PCP) on soil surface under irradiation of UV light in the laboratory has been investigated. Octachlorodibenzo-p-dioxin (OCDD) and heptachlorodibenzo-p-dioxin (H7CDD) were detected from the products of the photoreactions. The effects of soil types with different basic soil physicochemical properties were varied from silt loam, silt clay and clay soil on the formation of PCDDs by irradiation of PCP on soils surface. Fulvic acids can prevent phototransformation of PCDDs by photolysis of PCP on soil surface.

Benzopyrans↗
PubMed2002

Determination of pentachlorophenol (PCP) in waste wood--method comparison by a collaborative trial.

Two independently developed and validated procedures for the determination of pentachlorophenol (PCP) in waste wood were compared by means of a collaborative trial. Both methods foresee quantification of PCP by gas chromatography (GC-ECD) after acetylation and differ with regard to the use of methanol or toluene/sulphuric acid, respectively, as solvent in the sonication extraction step. Test samples with established analyte homogeneity were prepared from a ground "real life" starting material. A total of 23 participating laboratories with experience in wood preservative analysis were instructed to apply both methods to three levels of content in the range of 0.5-20 mg PCP/kg. In case of the toluene/sulphuric acid extraction, lower recoveries and higher interlaboratory dispersion of results at the higher PCP contents were observed. Seen against the background of the Horwitz equation a reproducibility standard deviation of approximately 19% for the methanol extraction at the 4.5 mg/kg level meets the requirement for a sound analytical method. Thus, the sonication extraction procedure with methanol has been annexed as a reference method to the German waste wood regulation.

Chemistry Techniques, Analytical↗
PubMed2003

Remediation of waters contaminated with pentachlorophenol.

We describe a simple method of remediating waters contaminated with pentachlorophenol (PCP), which involves filtering the water through clean soil. The filtrate is contaminant free and no PCP can be extracted from the soil. If the soil it treated with dilute acid, the filtrate is still contaminant free but 28.7% of the PCP can be extracted from the contaminated soil. Irradiating the soil with microwave energy either destroys or binds the PCP to the soil irreversibly such that none can be extracted after long periods of time.

Adsorption↗
PubMed2003

Fate of 1,2,3,4,6,7,8-heptachlorodibenzofuran and pentachlorophenol during laboratory-scale anaerobic mesophilic sewage sludge digestion.

The possibility of the formation of PCDDs and dechlorination of PCDFs during the anaerobic digestion of sewage sludge in laboratory scale digesters was investigated. Digesters were spiked with 1,2,3,4,6,7,8-HpCDF-13C(6) (240 ng/g organic matter (OM)) and pentachlorophenol (PeCP)-13C(6) (24 microg/g OM) and the output sludge monitored for 60 days. No dechlorination or formation of the labelled or native PCDD/Fs was observed. The detectable 1,2,3,4,6,7,8-HpCDF-13C(6) dechlorination yield was 0.0008-1% depending on homologue group and the detectable formation of OCDD yield was 0.00042% PeCP-13C(6). Preferential respiration of other, more bioavailable, substrates is suggested as the most plausible explanation for the lack of dechlorination. Formation of PCDDs from PeCP has been observed in aerobic environments but this study provides further evidence that it is not a precursor for formation during anaerobic digestion.

Anaerobiosis↗
PubMed2003

Kinetics of photodegradation and ozonation of pentachlorophenol.

The oxidation of 2,3,4,5,6-pentachlorophenol (PCP) has been carried out by a photodecomposition process using a polychromatic UV irradiation, and by an ozonation process. In the photodegradation process, the pH accelerated the decomposition rate and the approximate first-order rate constants were evaluated, with values between 0.16+/-0.005 min(-1) at pH=3 and 0.26+/-0.007 min(-1) at pH=9. A more rigorous kinetic study led to the determination of the quantum yields of the reaction, with values of 200+/-7x10(-3) mol/Eins for pH=3 and 22+/-1.1x10(-3) mol/Eins for pH=9. In the ozonation process, the rate constants for the reaction between ozone and PCP were determined by means of a competition kinetics, with values in the range from 0.67x10(5) to 314x10(5) l/mols. The specific rate constants for the un-dissociated and dissociated forms of PCP were also calculated. Finally, in both processes, the intermediate reaction products were identified, the most important being tetrachlorocatechol, tetrachlorohydroquinone and tetra-p-chlorobenzoquinone. Free chloride ion released, which was favored at high pHs, was also followed in both processes.

Hydrogen-Ion Concentration↗
PubMed2003

Removal of biocide pentachlorophenol in water system by the spent mushroom compost of Pleurotus pulmonarius.

Pentachlorophenol (PCP) has been widely used as a wood preservative since 1980s. Although it has been banned worldwide, residues of PCP are still commonly found. The spent compost of oyster mushroom Pleurotus pulmonarius (SMC) which was a degraded paddy straw-based substrate, contained 25% chitin. Five percentage of the SMC could remove 89.0 +/- 0.4% of 100 mg PCPl(-1) within 2 days at room temperature predominantly by biodegradation. The maximum removal capacity was 15.5 +/- 1.0 mg g(-1) SMC. The sorption kinetics of PCP by SMC can be described by the Freundlich monolayer model with a theoretical sorption capacity similar to that found for chitin. A PCP-degradative bacterium was isolated from the SMC. Yet, biodegradation was predominantly contributed by the immobilized ligninolytic enzymes secreted by the mushroom to the SMC. Degradation of PCP involves dechlorination, methylation, carboxylation and ring cleavage as verified by GC-MSD and ion chromatography. Thus, the SMC has a potential for treating PCP-contaminated water.

Adsorption↗
PubMed2003

A high-resolution model for estimating the environmental fate of multi-species chemicals: application to malathion and pentachlorophenol.

A high-resolution multi-species (HR-MS) model is presented that assesses the fate of up to four inter-converting chemical species. The current model has a more detailed environmental description than previous multi-species models in order to give a more accurate description of environmental fate. Improvements to the model environment include stratified air, soil and sediment compartments, the inclusion of a vegetation compartment, and the separation of the aerosol phase from the gas phase of the atmosphere. Such detailed environmental descriptions are particularly valuable when chemical heterogeneity is expected within environmental media as occurs with more reactive chemicals or local-scale simulations. The HR-MS model is illustratively applied to two situations for which a detailed environmental description is needed to describe the chemical fate accurately. The first example is the estimation of the atmospheric concentrations of malathion and its degradation product malaoxon following a local-scale application. The second example is a regional simulation of pentachlorophenol, which benefits from the more detailed treatment of ionizing chemical in the atmosphere. In both these cases, the HR-MS model is shown to be in good agreement with observed field data and provides a more accurate description of environmental fate than simpler multi-species models.

Environment↗
PubMed1997

Microbial response to repeated applications of low concentrations of pentachlorophenol in an alfisol under pasture.

Columns of an Alfisol under permanent pasture were polluted by repeated additions of pentachlorophenol (PCP) (7 mg l-1) to levels of 102 and 510 mg Kg-1, to simulate a dynamic diffuse pollution. PCP was rapidly sorbed to the soil organic matter, and was only slightly degraded. Measurements of soil microbial biomass-C revealed a 25% decrease in total biomass-C caused by both leaching and PCP toxicity. Microbial biomass-C measurements performed on soil fractions showed that only microorganisms located in the outer compartment of the aggregates were affected. Microorganisms protected by soil micro-aggregates were not affected, suggesting that they were not in contact with PCP, which was thus unavailable for biodegradation. Three gram negative bacterial strains (Si, C3 and C2), able to use PCP as a sole carbon and energy source, were isolated after 0, 1 and 3 months of PCP enrichment respectively, and were identified as Pseudomonas (Si) and Acinetobacter (C3 and C2). In liquid degradation tests, the strains C2 and C3 degraded 60% of PCP within 26 days whereas the Pseudomonas degraded only 25%. A specific immuno-labeling of the three strains permitted to show that repeated PCP additions to soil had a positive, negative or absence of effect on the populations C2, C3 and Si respectively.

Acinetobacter↗
PubMedDate not supplied

Atmospheric pentachlorophenol concentrations in relation to air temperature at five Canadian locations.

Pentachlorophenol (PCP), used as a wood preservative and as a disinfectant, has been found in human urine samples from Saskatchewan and in air samples from three Canadian sites. To confirm the presence of atmospheric PCP residues and to explore seasonality, weekly samples were collected at five Canadian sites for three consecutive weeks, in the months of July and October, 1995 and January, April and May, 1996, using a high volume sampler equipped with polyurethane foam (PUF) plugs. PCP was present in all samples collected adjacent to a utility pole storage site with concentrations ranging from 0.7 to 1233.0 ng m-3. There was a very strong correlation between average weekly air temperature, measured over a range of -29.3 to +20.0 degrees C, and the log10 of the average weekly concentration of PCP at this site. PCP was measured in 7 of 11 air samples from each of two small cities (concentrations ranging from 0.2 to 6.8 ng m-3) and the correlation between temperature and PCP concentration, for these two city sites, was similar to that for the utility pole storage site. Concentrations of PCP at two rural sites were lower (0.1-1.5 ng m-3) and detected less frequently. As a consequence, the correlation between air temperature and PCP concentration was more variable.

Air Pollution↗
PubMed1999

Biodegradation of low aqueous concentration pentachlorophenol (PCP) contaminated groundwater.

Bioremedial treatment to remove low level organic contamination to regulatory standards has met with limited success. In this study source water from a contaminated surficial aquifer at a former wood treatment facility was used to evaluate the potential for indigenous microorganisms to degrade low level (< 1.0 mg) pentachlorophenol (PCP) to a regulatory drinking water standard of 0.001 mg/L. PCP degradation was evaluated in series of batch reactors in a two phase study to (a) determine the rate and extent of PCP removal and (b) evaluate the impact of nutrient amendment (N and P) on removal rate. All reactors with the exception of the abiotic control demonstrated PCP removal to a level < 0.002 mg/L within a maximum period of 32 d with and without nutrient amendment. A regression analysis of reactive phosphate (ortho-P) concentration versus removal rate produced an R2 of 0.94 (p = 0.006) indicating a significant correlation between the level of available phosphate and PCP degradation rate. Selective bacterial enumeration (for PCP degrading bacteria) revealed PCP-degrading bacteria increased in abundance prior to and in conjunction with the degradation phase to a density of between 10(3) to 10(4) CFU/ml. Isolates were also analyzed for total fatty acids using Fatty Acid Methyl Ester (FAME) methodology and the results indicated that PCP degrading bacteria were present in the aquifer and consisted of predominately fluorescent, oxidase positive Pseudomonas species. Overall, data indicate that autochthonous microbes are capable of removing low level PCP (< 1.0 mg/L) to approach if not reach the regulatory standard of 0.001 mg/L with the addition of oxygen, with or without nutrient amendment. Results of this research can be applied to full-scale implementation of in-situ or ex-situ bioremediation of groundwater at former wood treatment facilities.

Bacteria↗
PubMed1999

Inefficiency of Mycobacterium chlorophenolicum PCP-1 to enhance mineralization of pentachlorophenol in soil microcosms.

We examined the mineralization of pentachlorophenol (PCP) in sterile and non-sterile soil with or without added bacteria (Mycobacterium chlorophenolicum PCP-1). The soil used had no history of PCP contamination. Microcosms (30 g dry weight of soil) were incubated with labelled PCP (6.76% 13C, a non-radioactive stable isotope, 22 mg kg-1 dry weight) for 60 days. M. chlorophenolicum PCP-1 (7.8 x 10(6) cells g-1 dry weight) was added to some samples. 50% of the PCP was mineralized in non-sterile soil with or without the exogenous bacteria. Only 5% of the PCP was mineralized in sterile soil with or without bacteria. These data suggest that the PCP was not accessible to M. chlorophenolicum and that the indigenous soil microflora can mineralize PCP.

Biodegradation, Environmental↗
PubMed1999

Sorption of pentachlorophenol on peat-bentonite mixtures.

Batch kinetic and isotherm studies were carried out to determine the adsorptive characteristics of peat and bentonite mixtures for pentachlorophenol, and to examine the hydraulic conductivity of peat-bentonite mixtures to determine if they are applicable for use as cutoff barriers. Batch kinetic studies showed that over 90% of PCP was removed from water spiked with approximately 1 mg/l of PCP using a peat-bentonite (5%) mixture. The equilibrium time was 8 hours. The optimum pH range for adsorption of PCP by the peat-bentonite mixture was found to be 3-3.5. Batch isotherm studies showed that the adsorption of PCP by the peat-bentonite mixture from aqueous solution was best described by the Freundlich isotherm equation. Batch adsorption studies using various ratios of bentonite in the mixture showed that the adsorption of PCP decreased linearly with increased amount of bentonite in the mixture, indicating that adsorption of PCP by the peat moss portion of the mixture was the dominant process. The inverse of the hydraulic conductivity was found to increase exponentially with an increase in the bentonite content of the mixture over the range studied. The minimum hydraulic conductivity observed was 3.3 x 10(-7) cm/s for a 50% peat-50% bentonite mixture. Peat-bentonite mixtures can be used to successfully remove PCP from aqueous media and can be used effectively as a barrier to attenuate the migration of PCP through soil and groundwater systems.

Adsorption↗
PubMed2000

Microtox testing of pentachlorophenol in soil extracts and quantification by capillary electrochromatography (CEC)--a rapid screening approach for contaminated land.

An approach to rapid soil testing which involved the use of simple solvent extraction methods was developed. The analytes of interest were priority pollutants of low water solubility which could not be readily removed from the soil using water. Direct toxicity testing of the soil samples by Microtox showed a high background toxicity which prevented realistic toxicity data from being obtained for the contaminants present. A range of different extraction solutions was used in an attempt to extract the contaminants while eliminating the matrix effects of the soil. It was necessary that the solvents selected for extraction of the soil samples were not of significant toxicity, as this could potentially mask the toxic effects of any compounds extracted from the soil. The extraction efficiencies of solvent systems were evaluated using pentachlorophenol (PCP) as a model compound of known toxicity in the Microtox assay. A rapid and cost-effective method was developed in order to determine the amount of PCP recovered from the soil by the extraction solvents employed. This method consisted of a solid phase extraction (SPE) step followed by quantification using capillary electrochromatography (CEC). Recoveries were greater when a higher proportion of organic solvent (methanol) was used in the extraction process, and lowest when water was used. An extraction based on water could provide information on the potential for leaching of contaminants from the soil into nearby water bodies in an environmental setting. An organic solvent extraction method could indicate how much toxicity soil-dependent organisms might be exposed to through ingestion. Extraction based on 50% (v/v) methanol in water was considered to be the most suitable overall extraction solution for soil screening, given that this permitted extraction of the water-insoluble compound PCP at a level which was clearly toxic in the Microtox assay while also retaining the capability to extract water-soluble contaminants.

Chemistry Techniques, Analytical↗