PCDD, PCDF, and PCB contamination of air and inhalable particulate in Rome

Summary The isomer specific determination of PCDD, PCDF and PCB was carried out on samples of air and inhalable particulate from Rome. Samples were taken daily for six months and pooled to yield two samples per month. Normal PCDD+PCDF concentrations expressed in TEQ ranged from 48 to 87 fg/m³, while total PCB ranged from 0.1 to 1.4 ng/m³. The 2, 3, 7, 8-substituted PCDD and PCDF congener pattern is shown together with the PCB congener pattern.     

Chlorobiphenyl (PCB) composition of extracts of subsurface soil, superficial dust and air from a contaminated landfill

Samples of 3 matrices (air, superficial dust and subsurface soil) from an aged PCB-containing landfill were extracted and the extracts refined for bioassay. Acetone:hexane extraction was modestly selected for non-planar compounds. Coplanar PCBs and PCDFs were enriched about 2-fold in the subsequent benzene:methylene chloride extracts of the soil. Extract refinement with Florisil slurry and alumina column chromatography did not appreciably change the composition of the extracts. CB 28 (2,4,4′-triCB) dominated in all extracts. The congener composition of soil and air were surprisingly similar, being enriched in tri- and tetraCBs while dust retained higher proportions of congeners with 4 and 5 chlorines. It is postulated that anaerobic dechlorination in the moist subsurface soil depleted the higher chlorinated congeners; more volatile congeners escaped into the atmosphere while moderately chlorinated congeners were trapped in the superficial dust and debris. The refined extracts represent distinct compositions of environmental PCB mixtures suitable for bioassay. Received: 21 November 1995 / Revised: 9 April 1996 / Accepted: 14 April 1996     

Improved Procedure for Single DB-XLB Column GC-MS-SIM Quantitation of PCB Congener Distributions and Characterization of Two Different Preparations Sold as “Aroclor 1254”

Complete PCB congener distributions in a panel of Aroclor mixtures were previously obtained by combining data from several HRGC systems. In that study quantitation of minor components may have been unreliable due to single level calibration against high levels of individual congener standards. Two lots of Aroclor 1254 had markedly different congener distributions. In this study, the design and performance of a congener-specific PCB analysis method employing GC-MS-SIM detection of congeners separated on a DB-XLB capillary column are discussed. Quantitation is carried out against a 6-level inclusive standard curve of a mixture of 144 congeners found in Aroclors. A separate procedure to measure trace levels of PCB 126 in Aroclors using the same system, combined with levels initially acquired for other congeners, facilitates estimation of TEQ values (Toxic Equivalencies of the PCB mixtures to 2,3,7,8-TCDD). PCB congener profiles of 15 Aroclor 1254 mixtures are presented. These profiles show that the less common, high TEQ variety of Aroclor 1254 was manufactured by an atypical, two-stage chlorination process that was apparently used during the final 1% of Aroclor 1254 production (ca. 1974–1976).     

Determination of dissolved and particle-bound PCB congeners at ultra-trace concentrations in water

Adsorption of 10 PCB congeners in aqueous solutions on glass-fibre filters taken from different boxes but of the same type were not significantly different. The standard deviations using filters from the same box were below 10% at concentration levels of 4.1?ng?L^?1. At this level, the adsorption of dissolved PCB at the filters was in the range of 5–20% depending on the congener. This led to a procedure for determination of dissolved and particle-bound congener in authentic landfill leachate, which included correction for adsorption losses. The procedure was based on filtration through glass-fibre filters, followed by trapping of the PCB in the eluate on solid-phase extraction (SPE) disks. After separate supercritical fluid (SFE) extractions, with carbon dioxide, of the filters as well as of the SPE disks, the extracts were analysed on a two-column capillary GC-ECD system. Corrections for congener adsorption on glass-fibre filters were made, from which corrected distribution constants between particle-bound and dissolved PCB congener in the water phase could be obtained for authentic landfill leachate. These values (10⁴–10⁵) agreed well with those obtained by others.     

High resolution gas phase chromatography-mass spectrometry of polychlorinated biphenyl congener residues in samples of biologic origin

A study is performed on polychlorinated biphenyl (PCB) congener residues in samples of human blood and milk as well as in falcon and pigeon eggs. Most of the PCB congeners found in these biological samples were quantified by high-resolution gas chromatography (HRGC). A PCB technical mixture--namely, DP6 (Phenochlor)--was used for the calibration as its composition was previously determined by HRGC-mass spectrometry. The usefulness of such a congener analysis is outlined. It is the first time to the best of our knowledge that a Phenochlor mixture is used for standardization.     

Development of a quantification methodology for polychlorinated biphenyls by using Kanechlor products as the secondary reference standard

Kanechlor (KC)-300, 400, 500 and 600, Japanese polychlorinated biphenyl (PCB) products, and their equivalent mixture were analyzed by using a gas chromatograph (GC) equipped with an SE-54 capillary column/electron capture detector (ECD) and a GC/mass spectrometer in the selected ion monitoring mode (MS-SIM). All peaks were assigned to the composing congeners based on the data on peak assignment of Clophen A-30, 40, 50, 60 and Aroclor 1016, 1242, 1254, 1260 [1] and on the relative retention time values of 209 PCB congeners [2]. The weight percentage of the congener(s) which corresponds to each peak in the mass chromatograms was calculated by comparison of its height with that of certified reference standard with the same molecular weight. Each weight percentage of PCB congener(s) corresponding to each ECD peak was obtained by summing up the percent contribution values of the PCB congeners co-eluting. The results showed that it was possible to use KC products and their equivalent mixture as secondary reference standards for congener-specific PCB quantification.     

Individual determination of ortho and non-ortho substituted polychlorobiphenyls (PCBs) in sediments by high performance liquid chromatographic pre-separation and gas chromatography/ECD detection

Summary An analytical procedure for the individual determination of ortho and non-ortho PCB congeners in sediments, using high performance liquid chromatography (HPLC) preseparation and gas chromatography/ECD detection, is described. Gas chromatography/FTIR spectrometry (GC/FTIR) and gas chromatography/mass spectrometry (GC/MS) were employed for individual congener identification and determination. Sample extraction, clean-up of extract and selective elution procedures were optimized by using reference certified marine sediment samples. Recovery and precision were typically 83% and 16% respectively at 2 ng/g of total PCB content. The proposed procedure, tested by analyzing real sediment samples, showed a reproducibility better than 20% at 13 ng/g PCB level.     

Polychlorinated naphthalene concentrations and profiles in cheese and butter,and comparisons with polychlorinated dibenzo-p-dioxin,polychlorinated dibenzofuran and polychlorinated biphenyl concentrations

Polychlorinated naphthalenes (PCNs) are candidates for inclusion in the Stockholm Convention on persistent organic pollutants. PCNs are structurally and toxicologically similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and its analogues. Intake in food is considered to be an important human exposure pathway for PCNs. In this preliminary study, cheese and butter samples were analysed for PCNs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) using an isotope dilution gas chromatography high-resolution mass spectrometry method. The aim of this study was to evaluate the PCN concentrations in the cheese and butter samples and to compare them with the PCDD, PCDF and PCB concentrations. The PCN concentrations were 5.6–103 pg g^?1 of wet weight in the seven cheese samples tested and 5.0–199 pg g^?1 of wet weight in the seven butter samples tested. The mass concentrations of lower chlorinated congeners were greater than those of the higher chlorinated congeners. Congeners of CN45/36, CN27/30 and CN33/34/37 were much more abundant than other congeners found in tetrachlorinated PCNs. Congeners of CN51, CN66/67 and CN73 were determined to be the predominant congeners in penta-, hexa- and heptachlorinated homologs, respectively. The PCNs contributed around 5% of the total PCN, PCDD, PCDF and PCB toxic equivalence (TEQ) values. CN73 was found to be the dominant PCN congener and contributed more than 40% to the PCN TEQ value. Congeners CN66/67, CN69 and CN63 were also found at relatively high levels. The PCB congener CB118 was the predominant congener (by mass-based concentration) of the 12 dioxin-like PCBs (dl-PCBs). The PCBs contributed 53.8% of the total TEQ, and congener CB126 contributed more than any other compound that was analysed to the total TEQ. The PCDDs and PCDFs contributed 11.6% and 29.7% of the total TEQ values, respectively.     

Complete PCB congener distributions for 17 aroclor mixtures determined by 3 HRGC systems optimized for comprehensive,quantitative, congener-specific analysis

Three HRGC systems (1: 30m DB-XLB capillary with MS-SIM detection; 2: 60m DB-XLB capillary with full-scan, ion-trap MS detection; and 3: Parallel dual-column DB-17 and series-coupled HP5/HT5 with ECD detection) were used to completely characterize multiple lots of 8 different-numbered Aroclor mixtures by quantitative calibration against 9 solutions containing primary standards of all 209 PCB congeners. Despite lower absolute sensitivity and more Aroclor congener coelutions than the dual-column ECD system, the MS systems enabled measurement of more congeners per Aroclor since their greater linear response range did not require dilution of samples and standards. Pairs of different lots of Aroclors 1248 and 1254 displayed markedly different proportions of congeners, and the 1254 pair displayed strong differences in the extent of ortho-chlorine substitution. The tables of congener weight percent distributions among Aroclors are more comprehensive and quantitatively precise than those of prior publications. However, the limitations of single-level calibration precluded measurement of all congeners to the ±10% accuracy desirable for establishing these Aroclors as secondary standards for comprehensive, quantitative congener-specific PCB analysis.     

A collaborative study of 209 PCB congeners and 6 Aroclors on 20 different HRGC columns 2. Semi-quantitative Aroclor congener distributions

Weight percents of PCB congeners in Aroclors 1221, 1016, 1242, 1254, 1260, and 1262 were determined by separately averaging resolved peaks quantified against standards of all 209 congeners in 9 HRGC-ECD and 9 HRGC-MS systems. A separate pair of systems provided nearly complete profiles of Aroclors 1232 and 1248. The tabulated values lack sufficient accuracy to qualify the Aroclors as secondary standards for comprehensive, quantitative, congener-specific analyses, but they provide more complete and accurate semi-quantitative characterizations of congener distributions for a larger number of Aroclors than prior publications.     

Direct analysis of mineral components in wine by inductively coupled plasma optical emission spectrometry (ICP-OES)

A direct measuring method for the determination of 15 inorganic components in wine by ICP-OES was developed. It was applied to 17 white wines from 6 German wine-growing regions. In these investigations 15 elements (B, V, Mn, Zn, Fe, Al, Cu, Sr, Ba, Rb, Na, P, Ca, Mg and K) were involved. By using alcoholic calibration solutions the results of the direct measuring method are comparable with those of the control methods. Typical patterns of elements obtained by the multicomponent analyses can be evaluated by multivariate data analysis to recognize the origin of the wines. Received: 30 May 1996 / Revised: 2 July 1996 / Accepted: 5 July 1996     

Direct analysis of mineral components in wine by inductively coupled plasma optical emission spectrometry (ICP-OES)

A direct measuring method for the determination of 15 inorganic components in wine by ICP-OES was developed. It was applied to 17 white wines from 6 German wine-growing regions. In these investigations 15 elements (B, V, Mn, Zn, Fe, Al, Cu, Sr, Ba, Rb, Na, P, Ca, Mg and K) were involved. By using alcoholic calibration solutions the results of the direct measuring method are comparable with those of the control methods. Typical patterns of elements obtained by the multicomponent analyses can be evaluated by multivariate data analysis to recognize the origin of the wines. Received: 30 May 1996 / Revised: 2 July 1996 / Accepted: 5 July 1996     

Measurements of coeluting unlabeled and C-labeled polychlorinated biphenyl congeners with partially overlapping fragment profiles using a tandem mass spectrometry

¹³C-labeled compounds are often employed as surrogate or internal standards to monitor the performance of extraction and instrumental analysis procedures for their unlabeled counterparts. However, labeled and unlabeled counterparts most often coelute chromatographically with overlapping mass ion fragments, posing a challenge to the accurate quantification of these compounds. In the present study, an analytical scheme, using coeluting unlabeled and ¹³C-labeled polychlorinated biphenyl (PCB) congeners as the model compounds, was developed with a low-resolution tandem mass spectrometer (MS/MS) to determine the appropriate ranges of PCB congener concentrations that satisfy the no-interference condition. Interferences from unlabeled PCBs to quantitation of labeled counterparts could be minimized when ¹³C-labeled PCB congeners were quantified in the MS/MS mode within a certain concentration range. In addition, good agreements between the measured and theoretically predicted quantitation errors were observed for all labeled PCB congeners except PCB 180. The exception with labeled PCB 180 was mainly attributed to the occurrence of instrumental analytical uncertainty, as analytical error was also observed with absence of unlabeled PCB 180. These results indicate that MS/MS techniques can serve as a useful tool to minimize interferences with quantitation of isotopically labeled compounds from their unlabeled counterparts, which possess partially overlapping ion fragment profiles.     

Multidimensional gas chromatographic separation of selected PCB atropisomers in technical formulations and sediments

A simple dual-column gas chromatographic system with a six-port switching valve has been used to separate the atropisomers of PCB congeners 84, 91, and 95 in technical PCB formulations and in extracts of soil and river sediment. A capillary column coated with a methylphenylsiloxane stationary phase (CP-Sil 8) was used as the first column, for retention window selection, and a permethylated β-cyclodextrin (ChirasilDex) capillary column as the main separation column. Because peak overlap could not be eliminated by optimization of column temperature, the enantiomeric ratios of PCB congeners could not be determined from the original chromatograms. The correct enantiomer ratio was determined from the peak areas obtained by deconvolution of the chromatograms. Whereas the PCB atropisomers considered were present in equal concentrations in the technical PCB formulations, analysis of a river sediment sample confirmed different residual concentrations of the atropisomers of congener 95.     

Toxic Congener-Specific Analysis of PCBs: Assessment of Toxicity in Equivalents of TCDD

Abstract

High resolution capillary gas chromatographic analysis of the polychlorobiphenyls (PCBs) present in snapping turtle eggs, provided quantitative data on selected toxic congeners. The concentrations of these congeners have been converted into equivalent toxic concentrations of 2,3,7,8-tetrachloro-p-dibenzodioxin (TCDD). The toxic equivalent factors (TEFs), necessary to effect this transformation were derived from EC₅₀ values (half the concentration of the toxic congener required to produce the maximum effect) for aryl hydrocarbon hydroxylase (AHH) induction associated with the corresponding toxic PCB congener or isomer. Summation of the resulting toxic equivalents provided a composite assessment of the toxlcity of the PCB mixture in terms of an equivalent concentration of TCDD.     

Relative performance of immunochemical (enzyme-linked immunosorbent assay) and gas chromatography-electron-capture detection techniques to quantify polychlorinated biphenyls in mussel tissues

Results from polychlorinated biphenyls (PCB) analyses of mussel tissue extracts by immunoassay (PCB RaPID Assay^®) and conventional gas chromatography-electron-capture detection (GC-ECD) are described and compared. Mussels from natural populations with diverse concentrations of PCBs, mussel tissue fortified with technical Aroclor^® 1254 and a certified reference material are included.A strong correlation is reported between “total” PCBs quantified by both techniques (r²=0.95, n=27). Immunoassay results, however, exhibited lower values compared to GC-ECD, particularly when GC results are corrected for procedural recovery. A reduced antibody response, due to differences in the congener composition between the mussel extracts and Aroclor^® 1254 (used to raise and calibrate the ELISA), provides the most likely explanation for this difference. Non-parametric statistical analyses confirmed that, although differing from Aroclor^® 1254, PCB congener compositions in the mussel extracts most closely resemble that of Aroclor^® 1254. At very high PCB concentrations (>30 μg g⁻¹ dry weight), however, ELISA results are statistically different (P<0.01) from GC-ECD results, which is likely to be related to the solvation capacity of ELISA diluent. Similarity analysis showed high correlations between the most prominent congeners in Aroclor^® 1254 and immunoassay results. This analysis did not, however, identify a specific chlorine substitution pattern to which the immunoassay preferentially responded.Whilst GC-ECD affords the capability to quantify individual congeners of different reactivity and toxicity, the data reported do indicate that immunoassay offers a rapid and inexpensive alternative method for estimation of “total” PCBs at environmentally significant levels. It is, however, necessary to remove extraneous lipids to reduce matrix effects in the immunoassay.     

Rock porosity determination by combination of X-ray computerized tomography with mercury porosimetry

First results are described of coupling of mercury porosimetry with X-ray computerized tomography (CT) as a new combination technique for rock porosity studies. This technique is suitable for rock samples with a pronounced mercury intrusion-extrusion hysteresis and includes CT measurements before and after mercury intrusion. The entrapped portion of mercury, when the pressure after the intrusion into the rock sample is reduced to 0.1 MPa, serves as a contrast agent in the porous network to localize spatial distribution of rock porosity by CT. The results obtained show that the mercury intrusion and therefore the porosity were quite different for the separate mineral phases. Therefore the combination of mercury porosimetry and computer tomography can give 3-D data on mineral-specific porosity distributions with additional pore size information. In contrast to mercury porosimetry as a single method, results of the combination technique with CT represent a direct visualization of porosity variation and do not depend on any special pore network model. Received: 2 July 1996 / Revised: 20 November 1996 / Accepted: 22 November 1996     

Rock porosity determination by combination of X-ray computerized tomography with mercury porosimetry

First results are described of coupling of mercury porosimetry with X-ray computerized tomography (CT) as a new combination technique for rock porosity studies. This technique is suitable for rock samples with a pronounced mercury intrusion-extrusion hysteresis and includes CT measurements before and after mercury intrusion. The entrapped portion of mercury, when the pressure after the intrusion into the rock sample is reduced to 0.1 MPa, serves as a contrast agent in the porous network to localize spatial distribution of rock porosity by CT. The results obtained show that the mercury intrusion and therefore the porosity were quite different for the separate mineral phases. Therefore the combination of mercury porosimetry and computer tomography can give 3-D data on mineral-specific porosity distributions with additional pore size information. In contrast to mercury porosimetry as a single method, results of the combination technique with CT represent a direct visualization of porosity variation and do not depend on any special pore network model. Received: 2 July 1996 / Revised: 20 November 1996 / Accepted: 22 November 1996     

Polychlorinated biphenyls,dibenzo-p-dioxins and dibenzofurans in soil samples from airport areas of Croatia

Levels and patterns of polychlorinated biphenyls (PCBs) were studied in surface soil samples collected in the coastal part of Croatia within and surrounding four different airports and in the vicinity of two partially devastated electrical transformer stations. The compounds accumulated from air-dried soil samples by multiple ultrasonic extraction with an n-hexane?:?acetone 1?:?1 mixture were analysed by capillary gas chromatography with electron capture and ion-trap detection. PCBs were quantified against a standard Aroclor 1242/Aroclor 1260 mixture and a standard mixture of 17 individual PCB congeners (IUPAC No.: 28, 52, 60, 74, 101, 105, 114, 118, 123, 138, 153, 156, 157, 167, 170, 180, and 189). The mass fractions of total PCBs in 18 soil samples collected within the airport premises ranged from 3 to 41?327?µg/kg dry weight (dw) (median: 533?µg/kg?dw), and those in 21 samples collected at a distance ranging from several metres to 5?km away from the airport fence, from <1 to 39?µg/kg?dw (median: 5?µg/kg?dw). The highest PCB levels were determined in soils along the airport aprons where the aircrafts were serviced and refuelled. The PCB pattern was very similar to technical Aroclor 1260 in all airport soils. The PCB pattern in 22 soils collected in the vicinity of electrical transformer stations was dominated by congeners contained in Aroclor 1242. These soils contained 7 to >400?µg/kg?dw of total PCBs. One highly PCB-contaminated airport soil sample was analysed for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). With an international toxic equivalent (I-TEQ) of 9.7?ng/kg?dw, the airport soil contamination was within values typical for urban and rural areas, and the congener patterns gave no clear indication for PCBs as the only source of PCDDs/PCDFs.     

A significant improvement of the gradient selected SELINCOR technique

 The gradient selected SELINCOR sandwich, a NMR pulse sequence for selecting the signal of a proton bound to a specific carbon atom, was modified and significantly improved by using a 180^° selective pulse on carbon. The sequence provides artifact-free carbon selected proton spectra and can serve as a building block for various applications. Received: 30 May 1996/Revised: 1 July 1996/Accepted: 3 July 1996