Supercritical fluid extraction of polychlorinated dibenzo-p-dioxins from municipal incinerator fly ash

The supercritical fluid extraction of polychlorinated dibenzo-p-dioxins from an incinerator fly ash sample has been investigated; supercritical nitrous oxide and its mixtures with methanol and toluene were employed as mobile phases. Recoveries of individual polychlorinated dibenzo-p-dioxins congeners were calculated from results of analysis of ¹³C-labeled dioxins by high resolution GC-MS employing selected ion monitoring. The extraction procedure was compared with extraction in a Soxhlet apparatus, which is currently used as a standard method for removing chlorinated dibenzo-p-dioxins from fly ash samples: the results indicated that the time required for the extraction and clean-up can be reduced from 24 to 2.5 hours/sample. Quantitative recovery of the chlorinated dibenzo-p-dioxins was achieved at μg/kg levels, the relative standard deviation was between 1.8 and 5.8%. The use of a virtually inert fluid such as pure nitrous oxide provides significant improvement over conventional extraction procedures because no solvent residue is left in the processed extract.     

Simultaneous determination of two serine proteinases by hydrophobic interaction chromatography

Summary An LC clean-up procedure based upon a complexation between polycyclic aromatic hydrocarbons (PAHs) and silica with chemically bonded 2,4-dinitroaniline has been combined with GC/MS. The LC pre-separation makes it possible to obtain a relatively clean fraction of PAHs free from alkanes, alkylbenzenes and naphthalenes, PCBs, chlorinated pesticides and many other interfering compounds. This fraction has been analyzed using capillary GC and mass selective detector (MSD). Substantial improvement of the MS spectra of PAHs with three or more fused benzene rings is achieved.     

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.     

Differences in retention of dioxin-like compounds and organochlorinated insecticides on an immunochromatographic column. Interpretation and applicability

The retention of organochlorinated compounds on an immunochromatographic column is studied. The compounds considered are usually found together in real samples of environmental concern, and include chlorinated biphenyls, chlorinated dibenzo-p-dioxins, chlorinated dibenzofurans, and organochlorinated insecticides. The different retention observed for different compounds is interpreted in light of the structural similarities of the compound studied with that used as a hapten to raise the antibodies employed as ligands in the immunochromatographic column. Differences in retention of the organochlorinated compounds on the immunocolumn make it possible to fractionate them. Mixtures of phosphate buffer solution and ACN in different ratios were used as desorption agents. Depending on the percentage of ACN employed, different fractionations of the organochlorinated compounds are obtained. The use of 20% ACN allows fractionation of most insecticides from chlorinated biphenyls, dioxins, and furans. Besides, chlorinated biphenyls of different chlorination degree can be separated. Moreover, pentachlorinated dioxins and pentachlorinated furans are separated from hexachlorinated biphenyls. Fractionation is of critical importance from a practical point of view, as it avoids some of the interferences that otherwise take place during the subsequent gas chromatography/mass spectrometry (GC/MS) analysis of these compounds. In this way, immunochromatography makes it possible to perform in a single step all the processes (extraction, clean-up, concentration, and fractionation) that are needed prior to the GC/MS analysis of these analytes in aqueous samples. An additional advantage of this method is the reusability of the immunoaffinity chromatography column for more than 500 times.     

Determination of Selected Chlorinated Priority Substances in Fish using QuEChERS Method with Dual dSPE Clean-up and Gas Chromatography

A rapid and simple analytical method for the determination of ten chlorinated priority substances (hexachloro-1,3-butadiene, pentachlorobenzene, hexachlorobenzene, hexachlorocyclohexane isomers, heptachlor, and heptachlor epoxides) in fish samples using QuEChERS extraction, dual dispersive solid-phase extraction (dSPE) clean-up, and GC analysis was developed. For the extraction, two published extraction/partitioning procedures were evaluated, and the recoveries obtained for the analytes (in range 54–98 % with RSDs ≤15 %) were in favour of the conventional QuEChERS method. The use of the dual dSPE clean-up yields cleaner extracts than in the case of single dSPE, which enables the use of ECD for the detection of the analytes and simplifies the maintenance of the GC system. The method was optimised using homogenates of chub fish that is frequently sampled for monitoring purposes. The linearity of the method was evaluated using matrix-matched calibration curves (in the range 2–50 μg kg⁻¹), and correlation coefficients (r ²) in the range 0.9927–0.9992 and RSDs of the relative response factors (RRF) below the value of 20 % were achieved. LODs ranged from 0.5 to 1.1 μg kg⁻¹, while LOQs ranged from 1.5 to 3.5 μg kg⁻¹. The accuracy of the method was verified by the analysis of the NIST standard reference material SRM 1946 (Lake Superior Fish Tissue), and most of the analytes of interest presented good agreement with the certified values.

     

Determination of selected persistent organochlorine pollutants in human milk using solid phase disk extraction and narrow bore capillary GC-MS

Summary A simple and rapid procedure based on solid phase disk extraction (SPDE), adsorption chromatography on acidified silica gel and GC-MS analysis was developed for the determination of 8 organochlorine pesticides and 19 PCB congeners in human milk. By using the SPDE procedure, a high throughput and parallel sample processing could be achieved. Method variables were optimized on whole cow's milk (3.5% fat) fortified at levels close to concentrations found in human milk. Recoveries of target analytes were acceptable and ranged from 69 to 102% and 86 to 120% for whole and skimmed milk, respectively. By the use of two stage clean-up and narrow bore capillary columns, detection limits as low as 20 pg mL⁻¹ could be obtained. The method was used for the determination of organochlorine pollutants in human milk from 19 individuals from Romania. The concentrations of PCBs were low, whereas those of organochlorine pesticides were higher than the values reported from other European countries.     

Organochlorine residue analysis of commercial milks by capillary gas chromatography

The determination of organochlorine pesticides and polychlorinated biphenyls in milks requires the use of efficient extraction methods. A rapid procedure has been developed, based on extraction of organochlorine residues from milk on to octadecylsilica solid phase extraction cartridges and elution with hexane. The addition of different organic solvents to the milk before solid phase extraction has been studied. The use of methanol to disrupt the fat globules enables almost complete recovery of the residues with minimum extraction of fatty substances. Recovery experiments were performed for eighteen compounds present at ppb levels in whole, two per cent, and skimmed milks. The average recoveries of the compounds from two per cent and skimmed milks were 73–84%; values for whole milk were lower. The residues were determined by gas chromatography using two kinds of capillary column (non-polar and semi-polar) and electron capture detection. The procedure shows low lipid carry over, and extraneous interferences are minimal. The method has been applied to the detection of organochlorine pesticides and nine individual polychlorinated biphenyls in commercial milks. The results obtained demonstrated the presence of very low levels of organochlorine residues in the commercial milks analyzed.     

Simple Procedures for Enrichment of Chlorinated Aromatic Pollutants from Fat,Water and Milk for Subsequent Analysis by High-Resolution Methods

Abstract

Procedures for enrichment of non-volatile chlorinated aromatic pollutants from fat, water and milk are described. ¹⁴C-DDT was used as a model compound in recovery experiments. A several thousand-fold enrichment of DDT added to butter was achieved by two consecutive straight-phase chromatographies on Lipidex 5000.

Trace amounts of DDT in liter volumes of water could be quantitatively extracted by rapid filtration through 2 ml beds of Lipidex 1000. A batch extraction procedure permitted enrichment of DDT from milk after addition of n-pentylamine, methanol and water. DDT could then be eluted from the gel with retention of more than 90% of the lipids.

A reversed-phase system with Lipidex 5000 could be used for separation of TCDD from DDT and PCBs. The liquid-gel chromatographic procedures are simple and suitable for clean-up of samples prior to application of high-resolution methods.     

Evaluation of Liquid–Liquid Extraction Methods for Determining the Levels of Lipids and Organochlorine Pollutants in Human Milk

Organic chlorine pesticides and polychlorinated biphenyls are organic pollutants that are stored in the adipose tissues of humans. The concentrations of those pollutants in human milk have previously been utilized as a biomarker for monitoring the body burden of lipophilic pollutants in humans. Liquid–liquid extraction methods have been applied to lipids, chlorinated pesticides, and polychlorinated biphenyls from breast milk. In this study, the effectiveness of four extraction methods, which have been widely used to isolate fats and organic pollutants from milk, were compared. The organic solvents included hexane, hexane/acetone (2:1, v/v), ethanol/ethyl ether/hexane (2:3:4, v/v), and methanol/chloroform (1:1, v/v). These results demonstrated that hexane yields the lowest extraction recoveries for lipids (approximately 21.3%) and analytes (approximately 50%). The other three organic solvents demonstrated better performance in extracting the target compounds, with the ethanol/ethyl ether/hexane system showing the optimum efficiency. The optimized system was employed to determine the analytes in human milk.     

Novel pressurized solvent extraction vessels for the analysis of polychlorinated biphenyl congeners in avian whole blood

Persistent organic pollutants remain a serious threat to many food-chain systems. New pollutants continue to emerge. The present study has created novel extraction vessels which are compatible with readily available commercial instrumentation to validate the analysis of one class of persistent organic pollutants, polychlorinated biphenyls (PCBs), in avian blood. The volumes used can be reasonably sampled without sacrificing individuals, or comprising breeding or migratorial success. The procedure consists of the pressurized solvent extraction (PSE) of analytes in a novel PSE extraction vessel. The new extraction cell contains a 38-cm long, coiled, re-packable, in situ clean-up column. Lipid elimination, using Florisil, occurs within the coiled region of the extraction vessel, eliminating the requirement for post extraction clean-up. For development, 0.2 g samples of chicken whole blood have been used. Extract volumes are reduced from (30 to 10) cm³, compared to unmodified systems. The new PSE vessel with its integrated clean-up method showed satisfactory performance for the analysis of ten environmentally relevant PCB congeners in chicken whole blood samples with recoveries in the range of (70-130)%. Detection limits using gas chromatography coupled with large volume injection ion-trap mass spectrometry (GC-LVI-ITMS-MS) were in the range of (0.05-0.5) ng g⁻¹. The relative standard deviations for all congeners investigated were better than 5%. This is the first PSE validation to have been conducted on unaltered whole blood samples.     

Development of a novel strategy for preconcentration of antibiotic residues in milk and their quantitation by capillary electrophoresis

A novel analytical method based on capillary zone electrophoresis coupled with diode array detection is developed and validated for the identification and simultaneous quantitation of four antibiotics in bovine raw milk. The studied antibiotics belong to different groups: β-lactams, tetracyclines, quinolones, amphenicols and sulfonamides. An experimental design including both a factorial and a central composite design allowed a reduction in the number of optimization experiments. The multiple response criterion was successfully used to optimize the separation between chloramphenicol, ciprofloxacin, ampicillin, tetracycline and sulfamethoxazol, allowing the reduction of the analysis time with excellent peak resolutions and low capillary current. Different strategies for preconcentration and extraction of the studied antibiotics were applied, in order to remove potential interferences from the sample and to increase the sensitivity. Milk samples were prepared by a clean-up/extraction procedure based on protein precipitation with trichloroacetic acid followed by liquid-liquid extraction with dichloromethane combined with solid-phase extraction, and injection into the electrophoretic system hydrodynamically. The limits of detection and quantification (below 30 and 100 μg L⁻¹, respectively) were in all cases lower than the maximum residue limits tolerated for these compounds in milk. Accuracy was evaluated by computing recoveries for the target antibiotics which were between 93.08% and 102.89%.     

Determination of endosulfan and some pyrethroids in waters by micro liquid-liquid extraction and GC-MS

A simple, rapid and reproducible method for the determination of some pesticide residues in water was developed using micro liquid-liquid extraction and gas chromatography - mass spectrometry with selected ion monitoring (GC/MS-SIM). The chlorinated insecticides α- and β-endosulfan and endosulfan-sulfate as well as the synthetic pyrethroids bifenthrin, permethrin, cypermethrin, fenvalerate and deltamethrin can be separated from a 500 mL sample water extracted with 0.5 mL of n-hexane containing anthracene-d₁₀ as internal standard without clean-up in only 13 min. The recovery efficiencies of the tested compounds yielded more than 93.0% at a fortification level of 5 ng mL^–1 and their relative standard deviations were between 1.9 and 11.7%. Detection limit of each compound ranged between 3 and 35 pg mL^–1. The method was applied to ground, sea and tap waters from Almería (Spain). The solubilities in water at 20°?C were determined.     

Application of capillary gas chromatography to environmental analysis

Routine analytical methods for benzo[a]pyrene and nitroarenes in airborne particulates are presented. Benzo[a]pyrene in airborne particulates was easily analyzed by a capillary GC/NCIMS. Analysis time was about 10 min and analytical values obtained by this method agreed well with those by HPLC/spectrofluorometry. Nineteen nitroarenes were analyzed by capillary GC/FTD following a simple clean-up procedure. Fifteen out of 19 nitroarenes analyzed were mutagenic for Salmonella typhimurium TA100 and TA98, and 4 nitroarenes were carcinogenic to experimental animals.     

Determination of coplanar and non-coplanar polychlorinated biphenyls in human serum by gas chromatography with mass spectrometric detection: electron impact or electron-capture negative ionization?

A time- and cost-saving method for the congener-specific analysis of polychlorinated biphenyls (PCBs) in human serum has been developed and validated. After two fast extraction and clean-up steps, analyses were performed using gas chromatography coupled with mass spectrometry with single ion monitoring (GC/SIM-MS), either in electron impact (EI) or electron-capture negative ionization (ECNI) mode. For the determination of dioxin-like congeners, an improvement in EI-MS sensitivity is desirable and use of NI is thus preferred. The procedure was validated for 12 dioxin-like congeners by analyzing spiked samples on three different days and using (13)C(12)-labelled analogues as internal standards. When using an NCI source, the limit of quantification was assessed at 0.01 microg/L, except for PCBs #77 and #81, which cannot be reliably detected below 0.05 microg/L. For the lower chlorinated non-dioxin-like congeners, NI offers less selectivity because of limited fragmentation. Electron impact ionization and electron-capture negative ionization mode can therefore be considered to be complementary for the determination of PCB congeners in the general population.     

Gas chromatography-mass spectrometric determination of polybrominated diphenyl ethers in complex fatty matrices from aquaculture activities

Gas chromatography coupled to mass spectrometry in negative chemical ionization mode (GC-(NCI)MS) has been applied to the quantification and reliable identification of polybrominated diphenyl ethers (PBDEs) in animal and vegetable samples from aquaculture activities. Matrices analyzed included fish fillet, fish feed, fish oil and linseed oil, their fat content ranged from 5% to 100%. Solid-phase extraction (SPE) (using Florisil and silica cartridges) and normal-phase high performance liquid chromatography were tested for an efficient clean-up in order to obtain sample extracts free of interfering compounds. Combining sulphuric acid digestion and SPE with Florisil led to the highest efficiency in the elimination of interferences from the extracts. The sample procedure developed, together with the application of GC-(NCI)MS for measurement, led to the satisfactory determination of PBDEs at μg kg ⁻¹ levels in complex aquaculture matrices with high lipid content. The use of a short and thin film-thickness fused-silica capillary column allowed to determine the problematic BDE 209 with satisfactory results. Three m/z ions were acquired for each analyte, which ensured a reliable identification of compounds detected in samples.     

High temperature (GC)2 and (GC)2/CI-MS of nucleosides: Analysis of purinyl nucleoside isomer composition

The analysis of low-volatile polar nucleosides by (GC)²/FID and (GC)²/CI-MS, employing HMDS-deactivated glass capillary columns and on-column injection, is described. The four linkage isomers of a specific nucleoside, formed in the synthetic procedure, are in each case sufficiently well separated in the chromatogram; GC/CI-MS allows for a differentiation of N-7 and N-9 linkage isomers.     

Fast solid phase extraction of polychlorobiphenyls and chlorinated pesticide residues from mussels using sep-pak cartridges

Summary A rapid method for the determination of chlorinated pesticides and polychlorinated biphenyls in mussels (Mytilus sp.) is reported. The mussel sample is homogenized and extracted with acetonitrile. The organic solution is concentrated and successively diluted with distilled water solution (12 g L⁻¹ NaCl). The organic compounds from water solution are adsorbed onto a NH₂ Sep-Pak cartridge. The clean-up step, in which the polychlorobiphenyls and chiorinated pesticides are separated in different eluates, is achieved by passing 25 mL of a 40% methanol aqueous solution through the NH₂ Sep-Pak and the C₁₈ Sep-Pak cartridges connected in series. The polychloroblphenyls are desorbed from the NH₂ Sep-Pak cartridge whilst the chlorinated peslicides are recovered from the C₁₈ Sep-Pak cartridge. In the separation of polychlorobiphenyls from the chlorinated pesticides tested in this work, only aldrin, hepatachlor and 4,4′-DDD are partially adsorbed with the polychlorobiphenyls onto the NH₂ Sep-Pak cartridge. The average recovery is ≥95.0% with a relative standard deviation ≤5.0%. The limits of detection for different pesticides and polychlorobiphenyl congeners are 0.01 and 0.008 μg Kg⁻¹. The final determination is carried out by capillary gas chromatography with ECD.     

A Total Solution to Baseline Separation of 20 Brominated Flame Retardant Additives in Electronic Products with Automated Soxhlet Hot Extraction and Gas Chromatography‐Mass Spectrometry

An efficient and reliable separation technique based on automated Soxhlet hot extraction (AHSE) was developed and validated. It can be applied to rapid separations of 20 persistent organic pollutants, including two types of brominated flame retardants (BFRs), polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs) contained in nonmetallic component parts of electronic products. The qualitative chromatographic analyses were carried out by using a gas chromatography coupled with a mass spectrometry detector (GC‐MS). The 20 persistent organic pollutants were simultaneously and completely separated by a 15 meter HP‐5MS short capillary column in 25 minutes. Through the tests of extraction performance, effects of solvent and extraction time on selected BFRs were investigated; toluene and 120 min extraction time were chose as the optimum conditions. Besides, this article examines the influence of temperature on the chromatographic analysis, the optimum temperature parameters were 280 °C and 320 °C for injector and column, respectively. The ASHE‐GCMS method was validated for the analysis of the certified reference material of CRM8110‐a and IRMM310. The limits of detection (LOD) for polymer sample was 0.55‐4.50 μg mL^?1; linearity range from 0.11 to 16 μg mL^?1. The proposed methodology can fully meet the requirement of relational directives.     

Determination of Polychlorinated Biphenyls and Chlorinated Pesticides in Environmental Biological Samples Using Focused Microwave-assisted Extraction

Abstract

Organochlorine compounds such as polychlorinated biphenyls (PCBs) and chlorinated pesticides have been analysed in environmental biological samples using focused microwave-assisted extraction (FMW). The analytical procedure is presented and the results for two Standard Reference Materials, a cod liver oil and a freeze-dried mussel tissue, are reported. The average recoveries for the sum of the PCBs are between 93% and 106%, and for the sum of the chlorinated pesticides are between 109 to 115% for all the certified compounds analysed. The developped analytical procedure is highly reproducible with an average standard deviation of 8% for the sum of the PCBs and 9.7% for the sum of the chlorinated pesticides in the two matrices.     

Solid-phase extraction clean-up procedure for the analysis of PAHs in lichens

A clean-up procedure based on a solid-phase extraction column was optimized for determination of polycyclic aromatic hydrocarbons (PAHs) in lichen extracts to remove co-extracted compounds from the matrix in the final extract. Several kinds of solid phases were evaluated: normal phase (-NH₂ and alumina), strong anion exchange and reversed phase. The -NH₂ columns were the most effective by using a packed solid bed of 500?mg. The lichen raw extract was loaded on the column previously conditioned with dichloromethane and hexane. Hexane (0.5?mL) was used as rinsing solvent, and PAHs were quantitatively eluted (80–97%) using 2?mL of hexane–dichloromethane (65–35) as eluting solvent. In these conditions, even the heaviest PAHs were quantitatively eluted. The optimized SPE method provides a short time and low-solvent-consumption sample clean-up compared with other conventional methods based on column chromatography. The analytical procedure, dynamic sonication-assisted extraction, followed by the optimized solid-phase extraction clean-up, was used to determine the 16 EPA priority PAHs from native lichens collected from the Aragon valley in central Pyrenees. The PAH concentrations in lichen samples ranged from 352 to 1654?ng?g^?1, and the minimum concentration value was established as the regional reference PAH levels in the area.