Critical review of the analysis of non- and mono-ortho-chlorobiphenyls

Non-targeted Screening in Environmental Monitoring Programs

Contaminant monitoring programs have been tasked with understanding the fate and transport of toxic chemicals in the environment. Mass spectrometry based methods have traditionally been developed to maximize sensitivity and accuracy of a select set of target compounds. As mass spectrometry methods have advanced, so has the breadth of questions proposed by environmental chemists. Incorporating these methods in chemical monitoring programs provides large data sets to explore the effects of complex mixtures on environmental systems.

Development of a new automated clean-up system for the simultaneous analysis of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and 'dioxin-like' polychlorinated biphenyls (dl-PCB) in flue gas emissions by GPC-SPE

A comprehensive clean-up method for quantitative analysis of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) in one single extract of environmental samples was developed. Since the chemical nature and toxicity of planar PCBs are similar to those of PCDD/Fs, dioxin-like PCBs and PCDD/Fs are often surveyed together in their exposure assessments. The development of a method for the simultaneous analysis of PCBs and PCDD/Fs in environmental samples is invaluable. The automated clean-up system evaluated in this work consists of three additional steps after traditional extraction: the chromatography on gel permeation (GPC), the concentration of the solvent through the use of an in-line evaporation module and the further purification and separation of PCDDs/Fs and dl-PCBs on an alumina cartridge in the 'SPE module'. In this work, three fly ash samples from an interlaboratory study with different PCDD/F and PCB levels were Soxhlet-extracted and then cleaned up using an automated system. PCDD/Fs and PCBs were determined using isotope dilution and high resolution gas chromatography/high resolution mass spectrometry. The determined values of 17 PCDD/Fs were consistent with the certified values and the relative standard deviations (RSDs) of the determined values were less than 20%. The recoveries of (13)C labeled PCDD/Fs and planar PCBs, and their RSDs were within the ranges specified in EPA1613 and 1668a methods, respectively. An accurate and reliable method was successfully developed and can be used in the simultaneous analysis of PCDD/Fs and planar PCBs in environmental samples.

Optimization of large-volume injection for the determination of polychlorinated biphenyls in children's fast-food menus by low-resolution mass spectrometry

This study includes the determination of five indicator polychlorinated biphenyls (PCBs) (52, 101, 153, 138, and 180), six non-ortho PCBs (35, 80, 81, 77, 126, and 169), and two mono-ortho PCBs (28 and 118) in fast food for children. A freeze-dried sample of 10 g is extracted by using pressurized n-hexane in two 5 min cycles at 120 degrees C and 100 mbar. Fatty extracts were cleaned up by means of acetonitrile/n-hexane partitioning and gel-permeation chromatography. The fractionation of non-ortho, mono-ortho, and indicator PCBs was made on graphitized carbon solid-phase extraction cartridges by using n-hexane, n-hexane/toluene (99:1, v/v), and toluene as elution solvents. Gas chromatography coupled to tandem mass spectrometry and large-volume injections with a programmed-temperature vaporizer (PTV-LV) were used to increase sensitivity and selectivity of the PCB determination. The PTV-LV injection settings, that is, vaporizing temperature, vaporizing time, and purge flow, were optimized by using a central composite design. A 15-40 times increased sensitivity was reached as compared with that obtained with the conventional 1 microL splitless injection. The limits of detection achieved were between 0.3 and 1.2 pg/g, and repeatability data, as relative standard deviation varied, ranged from 2 to 9% for the 0.05 ng/mL PCB level.

Challenges in the application of conventional PCB quantitation methods to studies of "invasive" freshwater organisms

We describe significant and unexpected errors in application of a conventional method for the quantitative determination of polychlorinated biphenyls (PCBs) in unusual biological tissue samples. A standard method based upon microwave-assisted extraction (MAE) and gas chromatography tandem mass spectrometry (GC-MS/MS) was applied to a variety of "invasive" freshwater organisms, representing a variety of genera. The 12 "co-planar" PCBs (co-PCBs) were determined at ng g(-1) levels in small samples (ca. 750-1000 mg) of eight freshwater species (n = 172). We found that the conventional method could lead to random and relatively large changes in retention times. A nearly five-fold increase in retention variability was observed for "lower" organisms compared to that observed in the analysis of predatory fish tissue. These unexpected retention time changes would result in misidentifications, and become problematic not only for non-selective detectors such as electron capture but also for MS-based approaches. That is, for electron impact (EI) ionization methods, molecular ions (M(+)) are produced by loss of Cl not only for congeners in the same homolog class but also for fragments of higher homologs (e.g. M - 35 and M - 37), thereby yielding false positive measurement of the target congener when the retention time windows overlap.

Analysis of alkylphenol and bisphenol A in eggs and milk by matrix solid phase dispersion extraction and liquid chromatography with tandem mass spectrometry

A method based on matrix solid phase dispersion (MSPD) using C18 as dispersant, and a subsequent cleanup step with amino-propyl solid phase extraction cartridges and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) has been developed for the simultaneous determination of nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in eggs and milk. Recovery studies were performed at different fortification levels. Average recoveries by MSPD varied from 79% of BPA to 98% of NP and relative standard deviations were equal or lower than 15% for egg samples. The average recoveries in milk ranged from 86 to 84% for BPA, 90 to 99% for NP and 82 to 103% for OP and relative standard deviations were equal to or lower than 8%. The limits of detection (LODs) in eggs were 0.10, 0.10 and 0.25 microg/kg for BPA, NP and OP, respectively and LODs for milk were 0.10, 0.05 and 0.10 microg/kg for BPA, NP and OP, respectively. Investigation of the levels in commercial samples indicated that NP was ubiquitous in milk and eggs at levels ranging from 4.24 to 17.60 microg/kg, and the milk samples were more heavily contaminated by NP than were the egg samples.

Sample pretreatment method for the determination of polychlorinated biphenyls in bird livers using ultrasonic extraction followed by headspace solid-phase microextraction and gas chromatography–mass spectrometry

A simple and reliable sample methodology based on simultaneous ultrasonic extraction, sulfuric acid clean-up and headspace solid-phase microextraction (SPME)-gas chromatography-mass spectrometry has been developed as an advantageous analytical tool for the determination of seven polychlorinated biphenyl congeners in bird livers at low levels. The influence of several parameters on the efficiency of the proposed method was systematically investigated. The clean-up efficiency of sulfuric acid treatment was tested and compared with those of column chromatography (Flosiril, silica gel and alumina) and solid-phase extraction (SPE) (Supelclean ENVI-Carb cartridge) procedures. The use of sulfuric acid in the clean-up step prior to headspace solid-phase microextraction analysis allows the removal of interfering matrix compounds present in the liver extracts that would otherwise cause severe ionization suppression of the polychlorinated biphenyls (PCBs) during the ionization process. The optimized method had good linearity (R2>0.99) over the range studied (5-500 ng/g wet weight) and showed satisfactory level of precision, with RSD values lower than 10.6%. The obtained relative recoveries ranged between 63 and 94%. The limits of detection (0.06-0.63 ng/g wet weight) were low enough to check for harmful levels of polychlorinated biphenyls in biological samples, and were well below most of the restrictive limits established by European Union regulations. The method was found to be reliable under the operational conditions proposed and was applied successfully to the analysis of individual polychlorinated biphenyls in liver tissues. The results obtained from five bird species from Greece revealed the presence of the target compounds in all samples analyzed, at levels ranging between 0.54 and 39.45 ng/g wet weight.

Determination of organochlorine pesticides and polychlorinated biphenyls in chicken eggs by matrix solid phase dispersion

A multiresidue method for the determination of 20 organochlorine pesticides (aldrin, endrin, dieldrin, alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, alpha-chlordane, gamma-chlordane, 4,4'-DDE, 4,4'-DDT, 4,4'-DDD, endosulfan I, endosulfan II, endosulfan sulfate, endrin aldehyde, heptachlor, heptachlor epoxide, endrin ketone and methoxychlor) and eight PCB congeners (PCB 20, 28, 52, 101, 118, 138, 153, 180) in chicken eggs has been developed and validated. The samples were extracted by a simple and fast matrix solid-phase dispersion (MSPD) method using Florisil as the sorbent material and dichloromethane/hexane (1:1) as the eluting system. Further purification of the extracts was conducted using a conventional clean-up procedure with concentrated sulphuric acid. Determination and quantitation of PCBs and OCs residues was carried out using a gas chromatograph equipped with an electron capture detector (GC-ECD). A mass spectrometric detector (GC-MS) in the selected ion monitoring (SIM) mode was used for confirmation purposes. The method detection limits were <0.7 ng g(-1) for all PCBs and OCs and the relative standard deviations for analyses of samples fortified over the range of 10-200 ng g(-1) were <8%. All compounds provided average recoveries (spiked at five concentration levels) ranging from 82% to 110%. The proposed method was used to analyze 30 commercial products taken from local markets in the course of a 3-month sampling campaign.

Microscale analytical methods for the quantitative detection of PCBs and PAHs in small tissue masses

Microscale methods (MM) were evaluated and compared to traditional methods (TM) for measuring polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in spiked and standard reference fish and mussel tissues. MMs are advantageous because they use small tissue masses (ca. 100mg), and maintain sensitivity through reducing final extract volume (traditionally 1 ml) by an order of magnitude or more (40 microl-PCBs; 100 microl-PAHs). Procedural losses occurred in the MMs' combined cleanup/primary evaporation step (19% PAHs; 6% PCBs), and the final extract concentration (14% PAHs; 22% PCBs). The PAH MM performed comparably to the TM. Although most PCBs had recoveries >50%, the PCB MM generally yielded lower recoveries than the TM. Average method detection limits were 0.6 microg/kg (TM) and 1.0 microg/kg (MM) for PCBs and 25.7 microg/kg (TM) and 27.7 microg/kg (MM) for PAHs. MMs described for PCB and PAH tissue samples are potentially viable alternatives to TMs, and could lead to cost savings in bioaccumulation/toxicity tests.

Concentrations and specific loads of UV filters in sewage sludge originating from a monitoring network in Switzerland

Many substances related to human activities end up in wastewater and accumulate in sewage sludge. The present study focuses on the analysis of widely used UV filters 3-(4-methylbenzylidene) camphor (4-MBC), octyl-methoxycinnamate (OMC), octocrylene (OC) and octyl-triazone (OT) in sewage sludge originating from a monitoring network in Switzerland. Mean concentrations in stabilised sludge from 14 wastewater treatment plants were 1780, 110, 4840 and 5510 microg/kg dry matter for 4-MBC, OMC, OC and OT, respectively. Specific loads in sewage sludge show that UV filters originate mainly from private households, but surface runoff and industries may be considered as additional sources. This indicates that besides use for sunscreens and cosmetics UV filters might occur in plastics and other materials and be released to the environment by volatilization or leaching. Differences between the modeled per capita loads of UV filters in sewage sludge and the observed specific loads in sewage sludge are probably due to erroneous figures of production volumes, degradation and sorption during wastewater treatment as well as degradation processes during transport in the sewer or sludge treatment. Thus, further research is needed to elucidate the fate of UV filters after application and release into the environment. Other compounds used as UV filters should be included in future studies.

Separation of Polychlorinated Biphenyls from Mineral Oil Using Alkylammonium Ion-Bonded Silica Stationary Phases

The potential of alkylammonium ion-bonded silica stationary phases for effective and simple pretreatment for determination of polychlorinated biphenyls (PCBs) in mineral oil samples is presented in this paper. The separation between PCBs and aliphatic hydrocarbons by normal phase chromatography was improved by using the alkylammonium ion-bonded silica stationary phases instead of alkylamine-bonded silica or other polar stationary phases. The number of alkyl residues bonded to the nitrogen atom was also an important factor of the separation.

Fast isolation of hydrophobic organic environmental contaminants from exposed semipermeable membrane devices (SPMDs) prior to GC analysis

Semipermeable membrane devices (SPMD) represent a passive sampling technology that is becoming widely used for monitoring of surface waters pollution. While "classic" procedures employ dialysis to recover target compounds from exposed SPMDs, in the present study analytes were isolated from cut membrane together with sequestering medium (triolein) using hexane as an extraction solvent. This approach allowed us to reduce the time needed for accomplishment of isolation step from 48 h to only 1 h. Automated gel permeation chromatography (GPC) clean-up is employed in the following step to separate triolein from analytes fraction. Musk compounds (MCs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and several other persistent organochlorine compounds (OCs) were determined in the respective fraction by GC method employing selective detectors (MSD, ECD). As shown in a series of analyses of SPMDs deployed in various aquatic ecosystems, high recoveries and good repeatability of results together with a possibility to obtain the information on the pollution of sampling site at the day of sample arrival to laboratory make this newly implemented procedure an interesting alternative to time consuming dialysis.

Trace analysis of polychlorinated dibenzo-p-dioxins, dibenzofurans and WHO polychlorinated biphenyls in food using comprehensive two-dimensional gas chromatography with electron-capture detection

Trace analysis of 2,3,7,8-polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and the 12 WHO-PCBs (four non-ortho and eight mono-ortho congeners that have been assigned toxic equivalence factors, TEFs, by the World Health Organisation) was conducted by comprehensive two-dimensional gas chromatography with a micro electron-capture detector (GC x GC-microECD). Four food matrices (fish oil from herring, spiked cows' milk, vegetable oil and an eel extract) were analysed by two GC x GC laboratories, and four GC-HRMS laboratories generated reference values. The two GC x GC laboratories used different column combinations for separating the target analytes. For the first dimension, non-polar DB-XLB and VF-1 columns were used, and for the second dimension, an LC-50 liquid crystalline column with unique selectivity for planar compounds. The congener-specific and total toxic equivalence (TEQ) data obtained using DB-XLB x LC-50 were in good agreement with results obtained by the GC-HRMS laboratories. The WHO-PCB data obtained with the VF-1 x LC-50 combination was also good, but the PCDD/F concentrations were sometimes overestimated due to matrix interferences. GC x GC-microECD using DB-XLB x LC-50 seems to fulfil the European Community requirements of a screening method for PCDD/F and WHO-PCB TEQ in food.

Fast miniaturised sample preparation for the screening and comprehensive two-dimensional gas chromatographic determination of polychlorinated biphenyls in sludge

Polychlorinated biphenyls (PCBs) in sludge are usually extracted by a technique such as Soxhlet with subsequent fractionation prior to long GC runs using GC-ECD or GC-HRMS. In this study, the extraction of selected chlorinated biphenyls (CBs) from a spiked sludge sample by three rapid techniques, i.e. ultrasonic (USE), pressurised-liquid (PLE), and microwave-assisted (MAE) extraction using a domestic microwave, was studied, with subsequent direct GC-ECD, GC-MS, or GC x GC-microECD analysis of the extracts. The main goal was to select an appropriate, and miniaturised, extraction method after only a brief optimisation and demonstrate the power of GC x GC analysis of dirty extracts. For PLE similar CB recoveries were found when extracting with either n-hexane or n-hexane/acetone (1/1). For USE and MAE, n-hexane/acetone (1/1) was the preferred extraction solvent. USE gave the best recoveries (80-95%; except 130% for CB 105). The only clean-up needed prior to GC-MS or GC x GC-gECD analysis was the removal of sulphur-containing compounds. GC-ECD was not suitable for these dirty extracts. The lowest LODs for the CBs (20 fg or 0.1 ng/g sludge) were found when combining USE and GC x GC-microECD, because of the powerful extraction, high separation power and excellent detectability provided by this technique.

Application of matrix solid-phase dispersion in the analysis of priority polycyclic aromatic hydrocarbons in fish samples

The performance of matrix solid-phase dispersion (MSPD) for the extraction of polycyclic aromatic hydrocarbons (PAHs) in fish tissue is described. The suitability of different solid supports was tested as well as the influence on the extraction efficiency of the natural fat content in samples. Under optimal conditions 0.6-0.8 g of tissue sample, are dispersed with 2 g of octadecylsiloxane (C18) and 0.5 g of anhydrous sodium sulphate and transferred to the top of a polyethylene solid-phase extraction cartridge which already contains 2 g of florisil and 1 g of C18. Cartridges were eluted with acetonitrile. The analysis of the extracts was carried out by high-performance liquid chromatography (HPLC) coupled with fluorescence detection. The proposed method provides detection limits between 0.04 and 0.32 ng/g for the different considered PAHs, below the maximum levels established by the some regulatory bodies for the six PAHs after recent oil spill episodes and European Union regulations. Recoveries over 80% were obtained for all compounds. Accuracy validation was carried out using the US National Institute of Standards and Technology (NIST) SRM 2977 reference material.

Investigation of saponification for determination of polychlorinated biphenyls in marine sediments

The effects of saponification conditions (temperature and water content of saponifying solution) on the determination of chlorinated biphenyls (CBs) in marine sediments were investigated. Although highly chlorinated biphenyls (nona- to deca-CBs) decomposed during high-temperature saponification, the degree of degradation was reduced by adding water to the ethanolic potassium hydroxide saponifying solution. Room-temperature saponification yielded quantitative recovery of highly chlorinated biphenyl surrogates but low extraction efficiencies of lightly chlorinated biphenyls (mono- to di-CBs). The same samples were analyzed by other extraction techniques, for example, pressurized liquid extraction, and analytical results were compared. The mono- and di-CB concentrations were correlated with the extraction temperatures of various extraction techniques. In particular, the concentrations of some CB congeners (CB11, CB14) were higher with saponification. The low degree of degradation of highly chlorinated biphenyls and the high recovery of lightly chlorinated biphenyls were compatible when room-temperature and high-temperature saponification were combined. Except for the anomalies of CB11 and CB14, the combined method gave satisfactory results for analysis of PCBs.

Developments in the use of chromatographic techniques in marine laboratories for the determination of halogenated contaminants and polycyclic aromatic hydrocarbons

Chromatography has been an important tool in marine laboratories. Since the 1960s, marine laboratories have been involved in the analysis of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and brominated flame retardants (BFRs). Column chromatography and liquid chromatography (LC) techniques have been used, mainly in the clean-up phase, while gas chromatography (GC) has been used extensively in the final determination of these contaminants. Developments have been observed from the use of packed GC columns, via capillary columns to the use of heart-cut multi-dimensional GC and comprehensive multi-dimensional GC. The progress made in interlaboratory studies and the availability of certified reference materials are discussed.

Methodological refinements in the determination of 146 polychlorinated biphenyls, including non-ortho- and mono-ortho-substituted PCBs, and 26 organochlorine pesticides as demonstrated in heron eggs

A method for the determination of 146 polychlorinated biphenyls (PCBs), including four non-ortho- and eight mono-ortho-substituted congeners, and 26 chlorinated pesticides is described. The method consists of ultrasonic extraction, Florisil cleanup, HPLC fractionation over porous graphitic carbon (PGC), and final determination with GC/ECD, GC/MS, or both. Two PCB congeners (PCB 30 and PCB 161) and two polybromobiphenyls (2,4',5-tribromobiphenyl and 3,3',4,4'-tetrabromobiphenyl) were used as surrogate standards to evaluate the analytical efficiency. Four PCB congeners, PCB 14 and PCB 159 for the first fraction, PCB 61 for the second fraction, and PCB 204 for the third fraction, were used as internal standards to monitor the GC performance. The retention behavior of PCBs and pesticides on the PGC column are discussed. The method was found to be reproducible, effective, and reliable under the operational conditions proposed and was applied successfully to the analysis of individual PCBs and chlorinated pesticides in black-crowned night heron (Nycticorax nycticorax) egg samples.

Development of a high-performance liquid chromatography carbon column based method for the fractionation of dioxin-like polychlorinated biphenyls

A method to separate polychlorinated biphenyls (PCBs) by using high-performance liquid chromatography (HPLC) was developed. The HPLC column was packed with Amoco PX-21 activated carbon dispersed on octadecylsilane (ODS). The separation was carried out by gradient elution with n-hexane-dichloromethane and toluene in the forward direction followed by reversed elution with toluene. The results show that this HPLC method is useful for the separation of PCBs according to the number of substituted ortho chlorine atoms attached to the biphenyl structure. Average recoveries for a number of individual di-ortho PCBs, mono-ortho PCBs, and non-ortho PCBs in three selected elution windows were 97, 92, and 96%, respectively. Clophen A50, a herring sample, and a cod liver oil sample were fractionated on the column and the analytical results are compared with data from the literature. The method presented here is useful for quantitative separations of mono-ortho PCBs as well as non-ortho PCBs which have been assigned toxic equivalency factors by the World Health Organisation.

Feasibility of high-performance immunochromatography as an isolation method for PCBs and other dioxin-like compounds

A high performance immunochromatographic procedure to isolate polychlorinated biphenyls (PCBs) and other dioxin-like compounds from a sample is shown. Development of the procedure includes (i) synthesis of the hapten, binding it to the spacer arm and to the carrier protein to make the immunizing molecule; (ii) raising and purification of anti-PCB antibodies; (iii) building of the immunocolumn; (iv) selection of the binding, rinsing, and elution conditions adequate for these highly lipophilic compounds; (v) study of the influence of the concentration and volume of sample on recovery; and (vi) study of the selectivity of the immunosystem for dioxins, furans, PCBs, and several insecticides of different toxicity. Evaluation of the method is carried out by analyzing the fractions retained and nonretained in the immunocolumn by GC/MS. The immunochromatographic system that is developed shows itself to be feasible as cleanup and isolation steps carried out prior to GC/MS analyses. When compared to classical cleanup and isolation methods traditionally used for analysis of PCBs in water, the immunochromatographic method is > 20x faster and uses 100x less organic solvents, and its selectivity is enormously enhanced. Good recoveries are obtained with both kinds of methods. The immunochromatographic procedure fulfils the acceptance criteria indicated by the EPA, even for sub-parts-per-billion concentrations.

Suitability of several carbon sorbents for the fractionation of various sub-groups of toxic polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans

Feasibility of several sorbents, Amoco PX-21, Carbosphere, Carbopack B and C and 2-(1-pyrenyl) ethyldimethylsilylated silica gel (PYE), for the fractionation of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans was investigated. Selection was based on their suitability for quantitative isolation of the target compounds with special attention for the most toxic mono- and non-ortho-CBs to prevent coelution with other congeners during the final determination by gas chromatography. Cost-effectiveness in terms of solvent and time consumption as well as feasibility for routine analysis and automation were considered additional merits of the methods compared. Final evaluation of the procedures providing the best results was done by comparison of the results obtained from the analysis of real-life samples. The results showed that, among the sorbents tested, Carbopack B and PYE were the most suitable for routine analysis. In particular, these sorbents allowed a more reliable determination of the toxic congeners and, consequently, of the toxic equivalents of 2,3,7,8-tetrachlorodibenzo-p-dioxin content in environmental samples.

Validation of an analytical procedure for polychlorinated biphenyls, coplanar polychlorinated biphenyls and polycyclic aromatic hydrocarbons in environmental samples

This work describes an efficient analytical procedure for the analysis of PCBs (polychlorinated biphenyls), coplanar PCBs and PAHs (polycyclic aromatic hydrocarbons) from the same sample. The method includes a solvent extraction followed by a combined purification-separation step on an alumina-silica column. Coplanar PCBs are isolated from the first fraction (PCBs) by a further high-performance liquid chromatography (HPLC) fractionation on a PYE [2-(1-pyrenyl)ethyldimethylsilylated silica gel] column. PCBs are identified and quantified by gas chromatography (GC) with electron-capture detection whereas GC with flame ionization detection or mass spectrometry are used for PAH determinations. This method allows the measurement of these contaminants in biota and sediment at trace levels as low as 1 pg g(-1) for coplanar PCBs with a precision better than 20%.

Separation of non-ortho polychlorinated biphenyl congeners on pre-packed carbon tubes. Application to analysis in sewage sludge and soil samples

The analysis of planar (non-ortho) polychlorinated biphenyls (PCB) by HRGC-ECD or HRGC-HRMS requires a fractionation step to avoid the interferences of the bulk of PCB, usually in much higher concentration than the planar ones. In this paper, a new method, based on the fractionation of PCB on SPE commercial tubes pre-packed with Carbopack B, has been developed. After the extract has been applied on the stationary phase, the bulk of PCD are eluted with 15 ml of hexane (fraction I), mono-ortho PCB with 20 ml of hexane/toluene 99:1 (fraction II) and planar PCB with 20 ml of toluene (fraction III) in a station under vacuum. The method has been validated: accuracy (expressed as recovery in %) is >70% and precision (expressed as % RSD) is <20% considering changes of day, analyst and batch of tubes. The method is linear in the range studied. Other advantages are that the method is simple, rapid and it can be easily automated. The application of this separation to the determination of planar PCB in fly-ash extracts from an intercalibration exercise and to sewage sludge, sediment and soil samples has been successful. In addition, this method removes hydrocarbons from the planar PCB fraction and allows its concentration to very small volumes.

Recent developments in the high-resolution gas chromatography of polychlorinated biphenyls

The capillary gas chromatography of polychlorinated biphenyls (PCBs) is reviewed. Focus is on the most recent developments in the separation and detection of PCBs rather than sample preparation methods. Included are a comprehensive look at stationary phases that have been used to separate PCBs and the relatively new work on chiral separations of PCBs. Mass spectrometry and atomic emission are presented as selective detection techniques. Suggestions for additional research are proposed where appropriate.