Separation of important PCBs and PAHs on a prototype smectic liquid-crystalline polysiloxane stationary phase capillary column

A prototype smectic liquid-crystalline polysiloxane GC column was tested as stationary phase for the separation of 7 BCR PCBs and 16 EPA PAH compounds. The separation efficiency on the smectic phase was much higher for both groups compared to a non-polar stationary phase column of the DB-5 type. Moreover non-ortho substituted (coplanar) PCBs were well separated from the mono-ortho and diortho PCBs and appeared as a late eluting group. Finally the smectic column is very useful for qualitative analysis of PAHs containing extracts.     

Formation and stability of polychlorinated biphenyl Pickering emulsions

An emulsion stabilized by colloidal suspensions of finely divided solids is known as a Pickering emulsion. The potential for polychlorinated biphenyls (PCBs) to form Pickering emulsions ex situ when in contact with powdered solids, such as clays and metal oxides, is investigated here. Bentonite, iron oxide and magnesium oxide dispersions proved to be robust Pickering emulsion stabilizers, whereas manganese oxide dispersions were not. Batch experiments revealed that emulsions can be formed using a moderately low energy input and can be stabilized with solid concentrations as low as 0.5 wt.%. For the base conditions (volumetric oil fraction (phi(oil))=30 vol.%; solid concentration (chi)=2 wt.%), the formed emulsions were indefinitely stable and the initial average droplet diameters varied from 80 to 258 mum, depending on the solid used in the colloidal dispersion. The average droplet size varied at early time, but for most conditions stabilized to a steady-state value 1 week after preparation. The effect of Ostwald ripening was limited. At greater than 0.5 wt.% concentration, the efficiency of the solid dispersion as a stabilizer was dependant on the volumetric oil fraction but not on the solid concentration. Generally, systems with volumetric oil fractions outside of the 20-70 vol.% range were unstable. The emulsions' droplet stability, average droplet size and size distribution were observed to vary as a function of the amount of energy provided to the system, the volumetric oil fraction, and the concentration of the solid in the aqueous dispersion. It is hypothesized that drilling through fractured rock in the immediate vicinity of dense, non-aqueous phase liquid (DNAPL) PCBs may provide both the energy and solid material necessary to form Pickering emulsions.     

Selective separation of deltamethrin by molecularly imprinted polymers using a β-cyclodextrin derivative as the functional monomer

A deltamethrin-imprinted polymer (MIP₁) was prepared using bis(-6-O-butanediacid monoester)-β-cyclodextrin (BBA-β-CD) as the functional monomer and toluene 2,4-diisocyanate (TDI) as the cross-linker. In comparison to the molecularly imprinted polymer where β-CD was applied as the functional monomer (MIP₂), MIP₁ showed a higher specific binding capacity (ΔC_P) and an improved imprinting factor (IF) for deltamethrin. The selective recognition experiments demonstrated that compared to MIP₂, MIP₁ could better recognize its template over other substrates that had similar chemical structures. The solid phase extraction (SPE) of deltamethrin using MIP₁ as the adsorbent was further investigated. The recoveries of the molecularly imprinted solid phase extraction (MISPE) column for deltamethrin were 83.2–93.4% with relative standard deviations (RSD) of 2.03–6.19%. The method has been successfully applied to the enrichment of trace deltamethrin from real water samples.     

Emission characteristics of PCDD/Fs, PCBs, chlorobenzenes, chlorophenols, and PAHs from polyvinylchloride combustion at various temperatures

The effect of temperature on polyvinylchloride (PVC) combustion using a downstream tubular furnace was investigated for the formation of polycylcic aromatic hydrocarbons (PAHs) and chlorinated compounds. As the temperature increased, higher levels of PAHs were generated. Chlorinated compounds reached a peak at 600 degrees C, with low emissions recorded at 300 and 900 degrees C. There was a close correlation (R2 = 0.97) among polychlorinated biphenyls (PCBs), hexachlorobenzene, pentachlorobenzene, and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). PAHs at all temperatures were analyzed in the gas phase. PCDD/Fs and PCBs were emitted as a solid phase at 300 and 600 degrees C and as a gas phase at 900 degrees C. For some PAHs, chlorobenzenes, and PCDD/Fs, a mathematical equation between the gas and solid phase and the reciprocal temperature in semilog proportion was derived. The proposed equation, which is log (amount in gas phase/amount in solid phase) = -A/T + B, where T is the temperature of the furnace and A and B are constants, for these species relating their gas/solid distributions showed a good relationship.     

Changes in Chlorinated Organic Pollutants and Heavy Metal Content of Sediments during Pyrolysis (7 pp)

Background There has been an increasing concern about the treatment and disposal of contaminated sediment from dredged river, harbor or estuary due to the accumulated toxic organics such as dioxins and inorganics particularly heavy metals like Cr, Pb, Zn, Cu, Hg and Cd. However, considering the huge amount of materials and financial costs involved, any candidate technology must ultimately result to reusable residual by-products. This can only be made possible if the toxic pollutants are removed or stabilized in the raw sediment and then fed back into the materials cycle. Currently, we are developing a pyrolysis process for the commercial-scale cleanup of dioxins and heavy metal-contaminated river sediment to yield reusable char for various economical applications. In this connection, this paper describes our preliminary investigation into the extent of dioxins and heavy metal volatilization from actual contaminated sediment. The stabilization of certain metallic species particularly Cr ions was studied. Methods Laboratory scale pyrolysis experiments were conducted using a special horizontal lab-scale pyrolyzer. Sediment samples from Shanghai Suzhou Creek and Tagonoura Harbor were pyrolyzed in the reactor under nitrogen gas at 800°C and different retention times of 30, 60 and 90 min. A constant heating rate of 10°C min-1 was employed. The pyrolysis gas was first allowed to pass through a cold trap to condense the tar. Uncondensed gases were then channeled through a column containing an adsorbent (XAD-2 Resin) for dioxins. Heavy metal concentrations in the initial and final sediment residues were analyzed by ICP (Nippon Jarrel-Ash) following their acid and alkali (for Cr6+) digestion. Dioxins content of the pyrolysis char, tar, and exhaust gases in the dioxin adsorbent were also determined. For comparative purpose, thermal treatment under air flow was conducted. Results The data for the removal of heavy metals from Suzhou Creek sediment showed very significant reductions in Pb, Zn and Cr6+ content of the sediment at this condition. Percentage removals were 42.4%, 60.8% and 42.2%, respectively. The disappearance of Cr6+ was due to reduction reactions rather than volatilization since the total Cr content remained almost unchanged. Other heavy metals such as Cu, Fe and Ni showed very minimal reductions. Nonetheless, Toxicity Characteristics Leaching Procedure (TCLP) tests confirmed that these residual heavy metals were rather stable in the pyrolysis char. Reduction of toxic Cr6+ at 42.2% has also been achieved by pyrolysis (with N2) as opposed to the more than 580 % increase in Cr6+ observed during thermal oxidation (with air). Discussion Pyrolysis also remove toxic organics particularly dioxins from the sediment. For the total dioxins, removal percentage of 99.9999% was achieved even at the lowest retention time of 30 min. Almost all polychlorinated dibenzo-p-dioxine (PCDDs) and polychlorinated dibenzo-furans (PCDFs) were removed at any retention time. The TEQs detected from the solid residues were mainly contributed by dioxin-like PCBs, yet these were present in relatively trace quantities. At the shortest retention time of 30 min, only 0.000085 pg-TEQ g-1 of polychlorinated biphenyls (PCBs) was detected in the pyrolysis char. Furthermore, the residual PCBs have very low toxicity ratings and none of the highly toxic PCBs, which were initially present in the sediment such as 3,3',4,4',5-PeCB and 3,3',4,4'5,5'-HxCB, were detected in the char. Results further confirmed that most of the dioxins that were removed were transferred to the gas phase so that volatilization may be considered as the main mechanism for their removal. Conclusion Some heavy metals particularly Pb and Zn can be volatilized under N2 pyrolysis at 800oC. Pyrolysis also prevented the formation of more toxic Cr6+ ions and at the same time resulted to its reduction by around 42.2% contrast to the 580% increase during thermal oxidation. PCDDs and PCDFs have been removed and were not formed in the solid products over the retention time range of 30-90 min at 800°C. Dioxin-like PCBs mostly remained and a retention time of 30 min was found sufficient for its maximum removal. Recommendations and Perspective . With the above results, a temperature of 800oC at a retention time of 30 min is sufficient for the removal of total dioxins and some heavy metals by volatilization. It is however necessary to destroy the dioxins as well as recover heavy metals in the gas phase. Stability of remaining heavy metals in the char also needs to be confirmed by leaching tests. These are the major concerns, which we are currently evaluating to establish the feasibility of our proposed large scale pyrolysis system for sediment treatment.     

表面活性剂冲洗修复多氯联苯污染土壤多相流研究

多氯联苯(PCBs)是一种具有持久性、抗生物降解性、脂肪溶性和明显的生物毒性等特性的持久性有机污染物,PCBs在土壤中难于准确定位、难被分解和强烈吸附,去除土壤中PCBs比较困难.表面活性剂冲洗法可以通过提高PCBs溶解度和降低水-PCBs界面张力来实现PCBs从土壤中去除;表面活性剂冲洗PCBs污染土壤涉及气相、水相、NAPLs相和固相等物质,是多相共存并相互发生作用的过程,发生相对渗透率、饱和度和毛细压力的变化;另外,为研究表面活性剂冲洗土壤中PCBs的去除机理,并降低PCBs对研究人员的危害,采用微观孔隙结构网络模型是一种较新颖的和效果显著的研究方法.开展表面活性剂冲洗PCBs污染土壤多相流研究,可以为PCBs污染场地修复提供理论基础和实验支持,并促进我国POPs履约工作的顺利进行.     

Selective supercritical fluid extraction to identify aged sediment-bound PCBs available for uptake by eel

A naturally contaminated sediment was partially extracted with selective supercritical fluid extraction (SFE) to remove a fraction of supposedly bioavailable PCBs from the matrix. Eels (Anguilla anguilla) were cultured in systems with untreated and pre-extracted sediment, respectively, and it was shown that the SFE treatment selectively removed bioavailable PCBs from the sediment, since relative biota-to-sediment accumulation factors (BSAFs) for the eight studied PCB congeners were much lower in the pre-extracted than in the untreated system at the end of the study. Relative BSAF values decreased with about the same relative amount for all eight congeners, independent of the degree of chlorination and the initial concentration in the sediment. The results demonstrate the ability of SFE to selectively remove sediment-bound PCBs that are available for uptake by the eels, thus demonstrating the feasibility of using selective SFE to estimate bioavailability of PCBs in sediments.     

Aircraft Release of Sulfur Hexafluoride as an Atmospheric Tracer

Abstract

The effect of temperature on polyvinylchloride (PVC) combustion using a downstream tubular furnace was investigated for the formation of polycylcic aromatic hydrocarbons (PAHs) and chlorinated compounds. As the temperature increased, higher levels of PAHs were generated. Chlorinated compounds reached a peak at 600°C, with low emissions recorded at 300 and 900°C. There was a close correlation (R² = 0.97) among polychlorinated bi-phenyls (PCBs), hexachlorobenzene, pentachloroben-zene, and polychlorinated dibenzo-p-dioxins and poly-chlorinated dibenzofurans (PCDD/Fs). PAHs at all temperatures were analyzed in the gas phase. PCDD/Fs and PCBs were emitted as a solid phase at 300 and 600°C and as a gas phase at 900°C. For some PAHs, chloroben-zenes, and PCDD/Fs, a mathematical equation between the gas and solid phase and the reciprocal temperature in semilog proportion was derived. The proposed equation, which is log (amount in gas phase/amount in solid phase) = ?A/T + B, where T is the temperature of the furnace and A and B are constants, for these species relating their gas/solid distributions showed a good relationship.     

A practical approach to the degradation of polychlorinated biphenyls in transformer oil

A practical and efficient disposal method for hydrodechlorination of polychlorinated biphenyls (PCBs) in transformer oil is reported. Transformer oil containing PCBs was treated by nanometric sodium hydride (nano-NaH) and transition metal catalysts. High destruction and removal efficiency (89.8%) can be attained by nano-NaH alone under mild conditions. The process exhibits apparent characteristics of a first order reaction. The reductive ability of nano-NaH was enhanced by the addition of transition metal catalysts. In the presence of TiCl4, 99.9% PCBs was hydrodechlorinated. The complex reducing reagents, Ni(OAc)2+i-PrONa, show extra hydrodechlorinating activity for di-chlorinated biphenyls.     

Elimination of persistent organic pollutants from fish oil with solid adsorbents

Fish oils are one of the main sources of ω-3 fatty acids in animal and human diet. However, they can contain high concentrations of persistent organic pollutants due to their lipophilic properties. The aim of this study is the reduction of persistent organic pollutants in fish oil using silicon-based and carbon-based solid adsorbents. A wide screening study with different commercially available adsorbents was carried out, in order to determine their capacity of pollutant removal from fish oil. Moreover, adsorption conditions were evaluated and optimized with using an experimental design and adjustment of the experimental results to response surfaces, obtaining removals rates of more than 99% of PCDD/Fs, 81% of dioxin-like PCBs, 70% of HCB, 41% of DDTs, 16% of marker PCBs and 10% of PBDEs. Finally, fish oil fatty acids were analyzed before and after the treatment with solid adsorbents, confirming that it did not affect its nutritive properties.     

Solid phase extraction with pyrenebutyric acid-bonded silica for analysis of polychlorinated biphenyls in sewage water by gas chromatography-mass spectrometry

A solid phase extraction (SPE) method using pyrenebutyric acid-bonded silica (PYB) as sorbent was developed to determine 23 polychlorinated biphenyls (PCBs) in sewage water by gas chromatography-mass spectrometry (GC-MS). Factors were optimized in SPE procedures including elution solvent, pH, and cartridge burden. The recoveries of 23 PCB congeners were 69.44-111.91% under optimized conditions. Comparisons were also conducted among PYB-SPE, C(18)-SPE and United States Environmental Protection Agency 608 (USEPA608) methods in the analysis of PCBs in sewage water samples. The results showed that the performance of PYB-SPE method was similar with USEPA608 method and better than C(18)-SPE method. Both PYB-SPE and USEPA608 methods were then employed to analyze PCBs in real spiked sewage water samples. The recoveries of PCB congeners determined by PYB-SPE method ranged from 70.6% to 92.4% in real spiked sewage water samples which were identified to be in accordance with USEPA608 method. Limits of detection (LOD) were in the range of 0.06-0.22ngL(-1) for PCB congeners. The optimized PYB-SPE method was successfully applied to the determination of PCBs in sewage water samples.     

Impact of edible oil injection on the permeability of aquifer sands

Recent laboratory and field studies have shown that food-grade edible oils can be injected into the subsurface for installation of in-situ permeable reactive barriers. However to be effective, the oil must be distributed out away from the oil injection points without excessive permeability loss. In this work, we examine the distribution of soybean oil in representative aquifer sediments as non-aqueous phase liquid oil (NAPL oil) or as an oil-in-water emulsion. Laboratory columns packed with sands or clayey sands were flushed with either NAPL oil or a soybean emulsion followed by plain water, while monitoring permeability loss and the final oil residual saturation. NAPL oil can be injected into coarse-grained sands. However NAPL injection into finer grained sediments requires high injection pressures which may not be feasible at some sites. In addition, NAPL injection results in high oil residual saturations and moderate permeability losses. In contrast, properly prepared emulsions can be distributed through sands with varying clay content without excessive pressure buildup, low oil retention and very low to moderate permeability loss. For effective transport, the emulsion must be stable, the oil droplets must be significantly smaller than the mean pore size of the sediment and the oil droplets should have a low to moderate tendency to stick to each other and the aquifer sediments. In our work, oil retention and associated permeability loss increased with sediment clay content and with the ratio of droplet size to pore size. For sandy sediments, the permeability loss is modest (0-40% loss) and is proportional to the oil residual saturation.     

Simultaneous quantification of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pharmaceuticals and personal care products (PPCPs) in Mississippi river water, in New Orleans, Louisiana, USA

An effective analytical method for simultaneously determining 16 polycyclic aromatic hydrocarbons (PAHs), 28 polychlorinated biphenyl (PCBs), and 12 pharmaceuticals and personal care products (PPCPs) has been developed to measure their concentrations in the Mississippi river waters in New Orleans, Louisiana, USA. The method involves the simultaneous extraction of the selected PAHs, PCBs, and PPCPs, from the aqueous phase by solid phase extraction using two-layer disks consisting of C(18) and SDB-XC, and collection of suspended solid in water samples by 0.2-0.6 microm filter in a single step. Target compounds adsorbed on the extraction disks were eluted with methanol, acetone, and dichloromethane. The suspended particles retained by the filter were sonically extracted using the same solvents. GC/MS was used for quantification of PAHs and PCBs directly and of PPCPs after derivatization. The analytical method was used in a 6-month field study of the Mississippi river water for contamination by PAHs, PCBs, and PPCPs and the following concentrations (ng/l) have been obtained: clofibric acid (3.2-26.7), ibuprofen (0-34.0), acetaminophen (24.7-65.2), caffeine (0-38.0), naproxen (0-135.2), triclosan (8.8-26.3), bisphenol A (0-147.2), carbamazepine (42.9-113.7), estrone (0-4.7), 17beta-estradiol (0-4.5), total PAHs (62.9-144.7), and total PCBs (22.2-163.4).     

Analysis method for PCBs in reclaimed oil using a fast-GC triple stage quadrupole mass spectrometer with the 13-component quantitation method

It is necessary for companies supplying reclaimed oil to analyze polychlorinated biphenyls (PCBs), because there is a possibility of the presence of contaminants due to trace-level PCBs in the reclaimed oil. However, common analysis methods of PCBs are time-consuming and complicated. Fast-GC triple stage quadrupole mass spectrometer with the 13-component quantitation method is an official method for analyzing PCBs in insulating oil in Japan. This method is extremely fast and simplified. The purpose of this study involves an investigation of the aforementioned fast and simple method for potential use in the analysis of reclaimed oil. Furthermore, it was attempted to combine the method with sample preparation involving only hexane dilution. The effect of sample dilutions corresponding to 100, 300, and 500 times was evaluated for reducing the matrix effect. The matrix effect was suppressed at a dilution ratio equal to or exceeding 300 times. Calibration curves of four points, namely 0.01, 0.05, 0.1, and 0.5 ng/mL, (ignored origin) by using an internal standard method were prepared for the 13 components. The square of regression coefficient (R²) values of all calibration curves exceeded 0.997. This method was adopted for the analysis of reclaimed oil containing 0.5 μg/mL PCBs, which corresponds to the judgment criteria, and accurate quantitation (accuracy value, 94.0–102%) and good repeatability (%RSD, 3.6%) were obtained. Furthermore, the required sensitivity was maintained even when 800 samples were analyzed without a cleaning ion source and an exchanging analysis column.     

Combined steam distillation and electrochemical peroxidation (ECP) treatment of river sediment contaminated by PCBs

A combined treatment process utilizing steam distillation followed by electrochemical peroxidation (ECP) has been utilized to remove >90% of the polychlorinated biphenyls (PCBs) in St. Lawrence River sediment and destroy 95% of the PCBs recovered in the condensate. 2 l of condensate were collected by boiling 500 grams of sediment containing 4.3 mg PCBs. Most of the PCBs (82.3%) were recovered as a small volume (<1 ml) of yellow oil floating on the condensate and coating glassware surfaces. The aqueous phase PCBs (182 μg/l) were destroyed (95%) by three sequential ECP treatments at 16.8°C and pH 5, utilizing 1 ml of H₂O₂ (3%) and periodically reversed current (0.75–1.0 A @ 10 volts). Oxidation is primarily mediated by hydroxyl radicals produced by the reaction of hydrogen peroxide with electrochemically generated ferrous iron (Fenton's reagent). This work suggests steam extraction, in combination with advanced oxidation technologies, provides an effective treatment strategy for contaminated solids.     

Coating effects on the glass adsorption of polychlorinated biphenyl (PCB) congeners

The effects of coating materials on polychlorinated biphenyl (PCB) adsorption in aqueous solution were assessed in an attempt to minimize PCB sorption loss during sampling processes. A coating material, which enhances PCB adsorption and allows adsorbed PCBs to be readily extracted by solvents, can act as a sampling concentrator to reduce PCB losses from both adsorption and evaporation. Several coating materials were evaluated, including paraffin oil, silicone oil, dimethyldichlorosilane (Sylon-CT), Prosil 28^® and polydimethylsiloxane (PDS) with viscosity 0.65, 50 (PDS 50), and 500 (PDS 500) cSt. PDS and silicone oil enhanced adsorption for all five congeners examined (IUPAC No. 28, 52, 101, 138, and 180). Sylon-CT, paraffin oil and Prosil 28^® had inconsistent effects on adsorption of different congeners. Desorption of adsorbed PCBs onto all coating types was assessed. The recovery efficiency of extracting PCBs with solvents was enhanced greatly with all coatings as opposed to non-coated surfaces, with the exception of paraffin oil. Coating with silicon oil, PDS 50, and 500 resulted in virtually 100% recovery of adsorbed PCBs. It was also found that Teflon containers were poor substitutes for glass containers and failed to minimize PCB losses. Among the materials studied, the best coating that could be used as a sampling concentrator was PDS 500.     

Bioavailability of PCBs from field-collected sediments: application of Tenax extraction and matrix-SPME techniques

Two chemical approaches, Tenax extraction and matrix solid phase microextraction (matrix-SPME), were evaluated for their potential to improve the prediction of bioavailability by equilibrium partitioning theory (EPT) across sediments with various characteristics. Biota-sediment accumulation factors (BSAFs) and body residues were quantified by exposing Lumbriculus variegatus to three PCB-contaminated field sediments. The concentration of PCBs in biota was positively correlated to the total PCB sediment concentration, the PCB concentration in the rapidly desorbing fraction estimated using Tenax extraction, and the PCB concentration on the SPME fibers. Results showed EPT was acceptable for estimating bioavailability from the tested sediments with sum PCB BSAFs of 1.18-2.47; however, it overestimated PCB bioavailability from sandy sediment. Both Tenax extraction and matrix-SPME, which take sequestration into account, reduced variability in prediction of PCB bioavailability across sediments, including the sandy sediment, and could be used as cost- and time-efficient alternatives for bioassay. Matrix-SPME was considered the better technique due to its ability to directly predict PCB body residues in the exposed biota and its potential use with in situ applications in the field.     

Determination of coplanar and ortho substituted PCBs in some sewage sludges of Switzerland using HRGC/ECD and HRGC/MSD

The three most toxic coplanar PCB congeners PCB 77, 126 and 169 as well as 7 mono-and di-ortho-PCBs (PCB 28, 52, 101, 118, 153, 138, 180) were measured in 19 sewage sludges. Concentrations of the coplanar PCBs ranged between 231–5050 ng/kg dw for PCB 77, 43–1511 ng/kg dw for PCB 126 and 29–273 ng/kg dw for PCB 169. Comparable results were obtained with mass selective detection in the single ion monitoring mode (MSD-SIM) except for PCB 169, where MSD-SIM was less sensitive than ECD. The sum of the 7 mono-and di-ortho-PCBs, which are routinely measured as representatives of the PCB fraction, reached levels between 43–550 μg/kg dw and agreed well with results previously obtained in our laboratory. Based on our data, a selective accumulation of the coplanar PCBs could not be observed. Sludges that received industrial effluents clearly showed higher PCB levels than rural ones. Finally, calculation of TEQ equivalents of the coplanar PCBs in the sewage sludges revealed that, based on application rates normally used in Switzerland, the contribution of the sludges to soil pollution seems to be of minor importance.     

Detection of PCBs in natural waters by front face fluorometry on solid sorbent on account of their fluorescence quantum yields and interaction with humic substances

A method for the detection of PCBs in natural water, based on extraction/concentration with tab shaped elements cut from C18 fiber glass SPE disks coupled with a fluorescence detection has been evaluated. The potential of the method was estimated through the measurement of the fluorescence quantum yields in acetonitrile and limits of detection (LOD) of 11 PCBs congeners and Arochlors 1221 and 1242 in pure water. Most of the LOD values are within the range of PCB concentrations found in highly polluted waters (<1microg l(-1)) and thus confer some interest to the method. However, as expected, naturally present humic substances was shown to compete with the solid phase for PCBs adsorption thus reducing the capability of the method when applied to natural waters. A Stern-Volmer plot of the fluorescence signal reduction in the presence of various type of humic substances leads to apparent sorption coefficients (K(DOC)) significantly higher than the literature values determined for PCBs or for polycyclic aromatic hydrocarbons, indicating that besides complexing PCBs, humic substances may also block some of the adsorption sites at the sorbent surface. An increase of the pH up to 11 was shown to reduce the negative effect of humic substances but their preliminary total denaturation or destruction appears as a prerequisite condition for taking full advantage of the present method.     

Isotope dilution analysis of polychlorinated biphenyls (PCBs) in transformer oil and global commercial PCB formulations by high resolution gas chromatography-high resolution mass spectrometry

Special polychlorinated biphenyls (PCBs) standards (native and isotope labeled) were analyzed by isotope dilution method using HRGC-HRMS. Multiple analysis of special PCBs standards by three different laboratories produced the relative response factors (RRFs) and relative standard deviations (RSDs %) was in the average of 0.979 and 3.86, respectively. Additionally, inter-laboratory analysis of various forms of transformer oil revealed the PCBs concentrations were in the following order; PCBs fortified transformer oil (940-1300 ng/g)>PCB polluted transformer oil (490-680 ng/g)>chemically degraded-transformer oil (480-490 ng/g) and PCBs free oil (ND-17 ng/g). Chemical degradation resulted in an order of magnitude decrease in the PCB concentrations. Specifically, higher chlorinated PCBs degraded into lower chlorinated PCBs. Also, composition of PCBs have been determined in PCB formulations from Japan (Kanechlor), Germany (Clophen), USA (Aroclor), Russia (Sovol) and Poland (Chlorofen). Major PCBs (24-PCB congeners) contributed 54-67%, 55-68%, 16-69%, 71% and 72% in Kanechlor, Clophen, Aroclor, Sovol and Chlorofen, respectively to total PCBs. The homologue pattern of Kanechlor, Aroclor and Clophen in technical fromulation was similar (e.g., Kanechlor-300 resembled to those of Clophen A-30 and Aroclor-1242). Furthermore, congener-specific distributions of major PCBs/dioxin-like PCBs and toxic equivalency quantities (TEQ) were calculated. Based on our tentative assumption calculations, cumulative production of five different technical PCB formulations, WHO-TEQ emission was estimated to be approximately 16.05 tons.