Airborne concentrations of toxaphene congeners at Point Petre (Ontario) using gas-chromatography-electron capture negative ion mass spectrometry (GC-ECNIMS).

A reliable analytical method has been developed using GC-ECNIMS for the determination of individual toxaphene congeners in ambient air. To allow a reasonable comparison with previous data for toxaphene reported by Muir and co-workers using GC-ECD, this method has adopted their approach of focussing upon the identification and quantification of specific peaks or clusters ("T" species) typically observed in environmental samples, with the sum of these "T" species then being reported as "total toxaphene". Technical toxaphene has been used as the analytical standard, but independent response factors have been assigned to the target peaks and clusters. Because of the appreciable variability in ECNIMS response shown by individual toxaphene congeners, this is considered to be a reasonable and potentially more accurate procedure than the application of a "single response factor" used by many other workers. The methodology has been used for the determination of toxaphene in air samples collected over the annual cycle in 1992 and then from October 1995 to September 1997 at Point Petre, Ontario. Of the forty-four calibrated components, only 10 were detected in all of the air samples collected over the latter 2-year period. Airborne concentrations of toxaphene (defined as the sum of the calibrated components) range from 0.9 pg/m3 to 10.1 pg/m3. A clear seasonality has been observed, with a summer-to-winter concentration ratio of about 6.     

Solid phase extraction with silicon dioxide microsphere adsorbents in combination with gas chromatography-electron capture detection for the determination of DDT and its metabolites in water samples

The goal of the present study was to investigate the feasibility of silicon dioxide (SiO₂) microspheres without special modification to enrich dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p′-dichlorodiphenyl-2,2-dichloroethylene (p,p′-DDD) and p,p′-dichlorodiphenyldichloroethylene (DDE) in combination with gas chromatography-electron-capture detection. The experimental results indicated that an excellent linear relationship between the recoveries and the concentrations of DDT and its main metabolites was obtained in the range of 0.2–30 ng mL^?1 and the correlation coefficients were in the range of 99.96–99.99%. The detection limits based on the ratio of signal to the baseline noise (S/N = 3) were 2.2, 2.9, 3.8 and 4.1 ng L^?1 for p,p′-DDD, p,p′-DDT, o,p′-DDT, and p,p′-DDE, respectively. The precisions of the proposed method were all below 10% (n = 6). Four real water samples were utilized for validation of the proposed method, and satisfactory spiked recoveries in the range of 72.4–112.9% were achieved. These results demonstrated that the developed method was a simple, sensitive, and robust analytical method for the monitoring of pollutants in the environment.     

Characterization of livestock odors using steel plates, solid-phase microextraction, and multidimensional gas chromatography-mass spectrometry-olfactometry

Livestock operations are associated with emissions of odor, gases, and particulate matter (PM). Livestock odor characterization is one of the most challenging analytical tasks. This is because odor-causing gases are often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this project was to develop a set of characteristic reference odors from a swine barn in Iowa and, in the process, identify compounds causing characteristic swine odor. Odor samples were collected using a novel sampling methodology consisting of clean steel plates exposed inside and around the swine barn for < or =1 week. Steel plates were then transported to the laboratory and stored in clean jars. Headspace solid-phase microextraction was used to extract characteristic odorants collected on the plates. All of the analyses were conducted on a gas chromatography-mass spectrometry-olfactometry system where the human nose is used as a detector simultaneously with chemical analysis via mass spectrometry. Multidimensional chromatography was used to isolate and identify chemicals with high-characteristic swine odor. The effects of sampling time, distance from a source, and the presence of PM on the abundance of specific gases, odor intensity, and odor character were tested. Steel plates were effectively able to collect key volatile compounds and odorants. The abundance of specific gases and odor was amplified when plates collected PM. The results of this research indicate that PM is major carrier of odor and several key swine odorants. Three odor panelists were consistent in identifying p-cresol as closely resembling characteristic swine odor, as well as attributing to p-cresol the largest odor response out of the samples. Further research is warranted to determine how the control of PM emissions from swine housing could affect odor emissions.     

Henry's law constants for hexachlorobenzene, p,p'-DDE and components of technical chlordane and estimates of gas exchange for Lake Ontario

The Henry's law constants (HLC) for trans- and cis-chlordane (TC, CC), trans-nonachlor (TN), hexachlorobenzene (HCB) and p,p'-DDE were determined by the gas-stripping method over a temperature range of 5-35 degrees C. The HLC variation versus temperature (K) was described by logH=m/T+b. Parameters of this equation were (with standard deviations) TC: m=-1524+/-158, b=6.58+/-0.54; CC: m=-1786+/-209, b=7.42+/-0.71; TN m=-2068+/-284, b=8.44+/-0.97; HCB: m=-3013+/-174, b=11.60+/-0.59 and p,p'-DDE: m=-2043+/-240, b=8.37+/-0.82. The HLCs (Pa m3 mol(-1)) at 25 degrees C (298.15 K) were: TC=29; CC=27; TN=32; p,p'-DDE=33 and HCB=35. These HLCs values were used to calculate fugacity ratios from paired air and water data from Lake Ontario, July 1998. The resulting fugacity ratios predict that volatilization was occurring for all compounds during that month.     

Comparison of quantitation of polychlorinated dibenzodioxins and polychlorinated dibenzofurans in complex environmental samples by high resolution gas chromatography with flame ionization, electron capture and mass spectrometric detection

A complete separation of PDDD and PCDF from a complex sample matrix by a two-step HPLC clean-up procedure shows the feasibility of analysis of PCDD and PCDF using less expensive instruments. This is demonstrated by a comparison of quantitative results of PCDD and PCDF in a complex flyash sample analyzed using GC/FID, GC/ECD, and GC/MSD.     

The evaluation of an analytical method for polychlorinated terpenes (PCC) in biological samples using an internal standard

The quantitative analysis of PCC (Toxaphene) residues in biological samples using gas chromatography with electron capture detection has been evaluated. Dechlorane 603, a chloroalicyclic compound is used as internal standard and modifications of the injection system for proper evaporation of this high-boiling compound is described. In the cleanup procedure PCB (and 1 – 3 % of the PCC) are removed by adsorption chromatography. Chlordane components and DDT compounds remaining in the PCC fraction constitute 5 – 10 % and 13 – 16 %, respectively, of the peak area in the chromatograms of the samples investigated. The quantitative results are influenced by the number of PCC-peaks chosen for the calculations and have to be specified together with the PCC-levels reported. The recoveries of PCC from spiked samples (20 ug PCC per gram crude fat above “natural” level) are 61 – 98 %, the lower figures obtained with samples containing low levels of PCC-residues. The practical limit of detection is about 10 ng PCC per g extracted fat.     

Rapid determination of dichlorodiphenyltrichloroethane and its main metabolites in aqueous samples by one-step microwave-assisted headspace controlled-temperature liquid-phase microextraction and gas chromatography with electron capture detection

A rapid and sensitive analytical method for the determination of dichlorodiphenyltrichloroethane (DDT) and its main metabolites in environmental aqueous samples has been developed using one-step microwave-assisted headspace controlled-temperature liquid-phase micro-extraction (MA-HS-CT-LPME) technique coupled with gas chromatography-electron-capture detection (GC-ECD). In this study, the one-step extraction of DDT and its main metabolites was achieved by using microwave heating to accelerate the evaporation of analytes into the controlled-temperature headspace to form a cloudy mist vapor zone for LPME sampling. Parameters influencing extraction efficiency were thoroughly optimized, and the best extraction for DDT and its main metabolites from 10-mL aqueous sample at pH 6.0 was achieved by using 1-octanol (4-μL) as the LPME solvent, sampling at 34 °C for 6.5 min under 249 W of microwave irradiation. Under optimum conditions, excellent linear relationship was obtained in the range of 0.05-1.0 μg/L for 1-dichloro-2,2-bis-(p′-chlorophenyl)ethylene (p,p′-DDE), 0.1-2.0 μg/L for o,p′-DDT, 0.15-3.0 μg/L for 1,1-dichloro-2,2-bis-(p′-chlorophenyl)ethane (p,p′-DDD) and p,p′-DDT, with detection limits of 20 ng/L for p,p′-DDE, and 30 ng/L for o,p′-DDT, p,p′-DDD and p,p′-DDT. Precision was in the range of 3.2-11.3% RSD. The proposed method was validated with environmental water samples. The spiked recovery was between 95.5% and 101.3% for agricultural-field water, between 94% and 99.7% for sea water and between 93.5% and 98% for river water. Thus the established method has been proved to be a simple, rapid, sensitive, inexpensive and eco-friendly procedure for the determination of DDT and its main metabolites in environmental water samples.     

Discrimination and thermal degradation of toxaphene compounds in capillary gas chromatography when using split/splitless and on-column injection

Technical toxaphene and a 22-component Reference Mixture were analyzed using capillary gas chromatography with split/splitless injection (SSL) and on-column injection (OC). In both techniques, electron-capture, negative ionization mass spectrometry (ECNI-MS) was used for detection of chlorobornanes, chlorocamphenes and related compounds. Significant discrimination of highly chlorinated congeners was observed as a result of incomplete transfer of these compounds from the vaporizer to the analytical column when using SSL. This resulted in a much lower response for nona- and decachloro congeners than when using OC. In addition, several toxaphene components, especially the chlorobornanes with gem dichloro substitution on the six-member carbon ring, undergo thermal degradation when using SSL. Some of these congeners are major components of technical toxaphene, but generally are not present, except at low concentrations, in environmental and biological samples. Therefore, technical toxaphene may be discriminated and/or degraded differently than toxaphene compounds in environmental samples when using SSL. This results in significant bias of the quantitative data when using the technical material as a reference. OC suffers much less from these deficiencies and, therefore, is a preferable technique for toxaphene analysis.     

Analysis of pesticide residues using the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) pesticide multiresidue method in traditional Chinese medicine by gas chromatography with electron capture detection

The Quick Easy Cheap Effective Rugged and Safe multiresidue method (QuEChERS) has been validated for the extraction of 15 organochlorine pesticides (OCPs) in completely different matrices of traditional Chinese medicine (TCM). The method employed a rapid, simple and cost-effective procedure. The spiking levels for the recovery experiments were 0.1, 0.5 and 2.0 mg kg⁻¹. Mean recoveries mostly ranged between 76.0% and 114.0% (96.0% on average), and relative standard deviations (RSD) were generally below 10% (4.72% on average). Based on these results, the methodology has been proven to be highly efficient and robust and thus suitable for monitoring the MRL compliance of a wide range of commodity. The contamination status of 15 OCPs on 80 different TCMs marketed in China, and a total of 400 samples were also performed using a previously validated method. 15 OCPs were benzene hexachloride (BHC, including α-BHC, β-BHC, γ-BHC, δ-BHC), hexachlorobenzene, heptachlor, heptachlor epoxide, aldrin, p, p′-DDE, p, p′-DDD, o, p′-DDT, p, p′-DDT, mirex, endrin, dieldrin. This study indicates that the proposed method is useful for analyzing OCPs in TCM.     

Polychlorinated biphenyls (PCB) and dichlorodiphenyltrichloroethane (DDE) air concentrations in the Lake Ontario region: Trends and potential sources

Airborne particle and gas samples were collected approx every 12 days from April 2002 to June 2006 at the Sterling Nature Center located near the southeast corner of Lake Ontario. These samples were analyzed for polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDE). Clausius-Clapeyron (C–C) regression analyses of PCBs and DDE yielded moderate correlations (r² = 0.54, p < 0.001; r² = 0.74, p < 0.001, respectively) indicating that much of the variations in concentrations can be explained by temperature. Back trajectory analysis indicated that the most important factors driving unusually high PCB partial pressures relative to those predicted by the C–C regression were slow wind speeds and winds generally from the southwest. This combination, which occurred frequently in 2004, increased contact of the air with contaminated upwind surfaces with minimum dilution. Hybrid receptor modeling (Potential Source Contribution Function (PSCF)) results for the total PCBs identified the midwestern US region that contains the urban areas of southern Indiana (IN), southwestern Ohio (OH), and northern Kentucky (KY) having the highest PSCF values. In general urban areas like Chicago (IL), Detroit (MI), Cleveland (OH), St. Louis (MO), and Nashville (TN) also had significant possibilities. In contrast, the PSCF modeling for DDE identified northern Alabama as the area with the highest probability where DDT was applied to cotton fields.     

A winter study of air,cloud and precipitation chemistry in Ontario,Canada

During January and February 1984, a field project was conducted near North Bay, Ontario, Canada. The principal objective was to characterize the chemical and microphysical properties of the air masses, clouds and precipitation in this region of NE North America during the winter season. Two extensively instrumented aircraft with some newly designed cloudwater and snow collectors were used, as well as a surface station continuously monitoring pollutant concentrations and a precipitation event sampling network. Pollutant concentrations at the surface were found to vary with the airmass back trajectory with the highest concentrations observed for trajectories from the S and SW and the lowest from the N. Vertical profiles of aerosol particle (0.2−2 μm diameter) and NOx concentrations show similar trends with maxima of 1200 cm⁻³ and 7 ppb, respectively near ground level with air mass trajectories from the S, in comparison to values of 250 cm⁻³ and 1 ppb obtained with trajectories from the N. Cloudwater, aircraft precipitation and ground precipitation samples had a daily median pH of 3.6,4.6 and 4.2, respectively with the cloudwater having the highest sulphate and nitrate concentrations. The nitrate/sulphate equivalent concentration ratios in the cloudwater, aircraft precipitation and ground precipitation samples were 0.7,0.6 and 1.4, respectively. The data suggest that precipitation scavenging of nitric acid below cloud base is an important process during the winter season.     

Observed trends for CF3-containing compounds in background air at Cape Meares, Oregon, Point Barrow, Alaska, and Palmer Station, Antarctica

The concentrations of CF(3)-containing compounds in archived air samples collected at Cape Meares, Oregon, from 1978 to 1997, at Point Barrow, Alaska, from 1995 to 1998, and at Palmer Station, Antarctica, from 1991 to 1997, were determined by high resolution gas chromatography and high resolution mass spectrometry. The CF(3)-containing compounds measured by this method and discussed here are: the perfluorinated compound, C(3)F(8) (FC 218); four perhalogenated compounds, CF(3)Cl (CFC 13), CF(3)CF(2)Cl (CFC 115), CF(3)CFCl(2) (CFC 114a), and CF(3)Br (Halon 1301); and three hydrofluorocompounds, CF(3)H (HFC 23), CF(3)CH(3) (HFC 143a), and CF(3)CH(2)F (HFC 134a). For four of these compounds, very few measurements have been previously reported. The atmospheric concentrations of all of the CF(3)-containing compounds continuously increased in time over the sample collection periods. From these data, the annual rates of emission into the atmosphere have been estimated. The emission rates fall into one of three distinct categories. The annual emission rates of C(3)F(8), CF(3)H, CF(3)CH(3), and CF(3)CH(2)F have continuously increased over the last two decades. That of CF(3)CFCl(2) has decreased continuously. Emission rates for CF(3)Cl, CF(3)CF(2)Cl, and CF(3)Br reached maximum levels in the late 1980s, and have been decreasing in the 1990s. The emission rates of C(3)F(8), CF(3)CH(3) and CF(3)CH(2)F were nearly zero 20 years ago but have increased rapidly during the last decade.     

Preliminary evaluation of bitumen contamination in environmental samples using comprehensive gas chromatography GcxGc – Time of flight mass spectrometry (GCxGC-TOFMS)

Abstract

Bitumen and bitumen impacted soil and water samples were investigated for their relative chemical composition using comprehensive gas chromatography GcxGc – time of flight mass spectrometry (GCxGC-TOFMS). The results reveal the presence of key compounds which could serve as environmental biomarkers for bitumen impacted soils and aquifers. Prominent alkanes such as 3-methylpentane; 2,2,4-trimethylpentane; 1,3,5-trimethyladamantane; 2,6,10-trimethyldodecane; 3-ethyl-2,2-dimethyl pentane were tentatively identified and are likely potent biomarkers in environmental forensic assessment of bitumen contamination while the presence of some aromatic compounds: 1,2-benzenedicarboxylic acid, 1,2-dimethyl-3-propylbenzene; 3,4-bis(methoxycarbonyl)benzoic acid; 1,3-bezenedicarboxylic acid, 1,2-benzenediol; 1,3-dimethylbenzene; 1,2-2-(2-ethylhexoxycarbonyl)benzoic acid; (4-methylpentan-2-yl)benzene; 2,4-dimethyl benzo(H)quinolone will further confirm the bitumen contamination in an area under investigation. A host of additional compounds were tentatively identified, mainly in the bitumen samples. The results obtained in this study provides baseline data for effective monitoring, and source apportionment of oil/oil products spills.     

Cell bioassays for detection of aryl hydrocarbon (AhR) and estrogen receptor (ER) mediated activity in environmental samples

In vitro cell bioassays are useful techniques for the determination of receptor-mediated activities in environmental samples containing complex mixtures of contaminants. The cell bioassays determine contamination by pollutants that act through specific modes of action. This article presents strategies for the evaluation of aryl hydrocarbon receptor (AhR)-(hereafter referred as dioxin-like) or estrogen receptor (ER)-mediated activities of potential endocrine disrupting compounds (EDCs) in complex environmental mixtures. Extracts from various types of environmental or food matrices can be tested by this technique to evaluate their 2,3,7,8-tetrachlorodibenzop-dioxin equivalents (TCDD-EQs) or estrogenic equivalents (E₂-EQs) and to identify contaminated samples that need further investigation using resource-intensive instrumental analyses. Fractionation of sample extracts exhibiting significant activities, and subsequent reanalysis with the bioassays can identify important classes of contaminants that are responsible for the observed activity. Effect-directed chemical analysis is performed only for the active fractions to determine the responsible compounds. Mass-balance estimates of all major compounds contributing to the observed effects can be calculated to determine if all of the activity has been identified, and to assess the potential for interactions such as synergism or antagonism among contaminants present in the complex mixtures. The bioassay approach is an efficient (fast and cost effective) screening system to identify the samples of interest and to provide basic information for further analysis and risk evaluation.     

固相萃取—气相色谱质谱法测定水样中的毒死蜱及其代谢产物

建立了水样中毒死蜱及其主要代谢产物3,5,6-三氯吡啶醇(TCP)的固相萃取—气相色谱质谱检测法,即采用固相萃取对水样中的毒死蜱及其代谢产物TCP进行富集,浓缩后经双(三甲基硅烷基)三氯乙酰胺(BSTFA)衍生TCP,采用气相色谱质谱进行测定。同时,采用外标法对毒死蜱和TCP进行定量。结果表明,该方法的线性范围为20~1 000μg/L,毒死蜱和TCP的检出限分别为0.375、0.100μg/L;环境水样中的毒死蜱和TCP平均加标回收率分别为89.12%~93.44%和87.37%~90.75%,相对标准偏差(RSD)为2.79%~6.64%和1.22%~5.48%。     

Comparison of an enzyme-linked immunosorbent assay (ELISA) to gas chromatography (GC)--measurement of polychlorinated biphenyls (PCBs) in selected US fish extracts

The analysis of PCBs in fish tissues by immunoassay methods was evaluated using fish collected from a US monitoring program, the National Contaminant Biomonitoring Program of the US Department of Interior, Fish and Wildlife Service. Selected composite whole fish samples, which represented widely varying concentrations and sources of PCBs, were extracted and subjected to congener PCB analysis by gas chromatography (GC) and total PCB analysis using an ELISA (ePCBs) calibrated against technical Aroclor 1248. PCB congener patterns in these fishes were different from the patterns found in commercial Aroclors or their combinations as demonstrated by principal component analysis of normalized GC congener data. The sum of the PCB congeners measured by GC (total-PCBs) ranged from 37 to 4600 ng/g (wet weight). Concentrations of PCBs as determined by the ELISA method were positively correlated with total-PCBs and the ePCBs/total-PCBs ratios for individual samples ranged from 1 to 6. Ratios of ePCBs/total-PCBs for dilutions of Aroclors 1242, 1254, and 1260 and for matrix spikes range from 0.6 for 1242 to 2.5 for 1254 and 1260. These results suggest that higher chlorinated PCB congeners have higher affinity for the anti-PCB antibodies. Partial least squares with latent variable analysis of GC and ELISA data of selected Aroclors and fish samples also support the conclusion that ELISA derived PCB concentrations are dependent on the degree of chlorination.     

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Environmental Science and Pollution Research -     

Quantitative trace analysis of polyfluorinated alkyl substances (PFAS) in ambient air samples from Mace Head (Ireland): A method intercomparison

A method intercomparison study of analytical methods for the determination of neutral, volatile polyfluorinated alkyl substances (PFAS) was carried out in March, 2006. Environmental air samples were collected in triplicate at the European background site Mace Head on the west coast of Ireland, a site dominated by ‘clean’ westerly winds coming across the Atlantic. Extraction and analysis were performed at two laboratories active in PFAS research using their in-house methods. Airborne polyfluorinated telomer alcohols (FTOHs), fluorooctane sulfonamides and sulfonamidoethanols (FOSAs/FOSEs) as well as additional polyfluorinated compounds were investigated. Different native and isotope-labelled internal standards (IS) were applied at various steps in the analytical procedure to evaluate the different quantification strategies. Field blanks revealed no major blank problems. European background concentrations observed at Mace Head were found to be in a similar range to Arctic data reported in the literature. Due to trace-levels at the remote site, only FTOH data sets were complete and could therefore be compared between the laboratories. Additionally, FOSEs could partly be included. Data comparison revealed that despite the challenges inherent in analysis of airborne PFAS and the low concentrations, all methods applied in this study obtained similar results. However, application of isotope-labelled IS early in the analytical procedure leads to more precise results and is therefore recommended.     

Distribution equilibrium of mercury (II) chloride between water and air applied to flue gas scrubbing

In the literature, different values of the distribution coefficient KH for HgCl2 between water and air are present in a range that spans more than 3 orders of magnitude. In order to determine if a waste incineration scrubber solution could become saturated with regard to HgCl2, an accurate experimental determination of the distribution constant of HgCl2 at elevated temperatures is needed. In this work, the coefficient has been determined at four different temperatures between 10 and 50 degrees C. The Arrhenius expression obtained is 5.5 x 10(5) x exp[-(8060 +/- 2200)/T] with a corresponding enthalpy for the process HgCl2(aq)<==>HgCl2(g) of 67 +/- 20 kJ/mole. KH at 293 K was found to be approximately 5 x 10(-7) atm M-1, which is in almost perfect agreement with an earlier study. Applying the obtained KH values to waste incineration scrubber conditions shows that no major saturation effect will occur.     

A simple spectrophotometric method for the determination of cobalt in industrial, environmental, biological and soil samples using bis(salicylaldehyde)orthophenylenediamine

Bis(salicylaldehyde)orthophenylenediamine (BSOPD) has been proposed as new analytical reagent for the direct non-extractive spectrophotometric determination of cobalt. It reacts with cobalt in slightly acidic (0.0002-0.001 M H(2)SO(4)) 50% 1,4-dioxanic medium to form a red-orange chelate with a molar ratio 1:1. The reaction is instantaneous and the maximum absorbance was obtained at 458 nm and remains constant for over 24h. The average molar absorption coefficient and Sandell's sensitivity were found to be 1.109 x 10(4)l mol(-1)cm(-1) and 20 ng cm(-2) of Co(II), respectively. Linear calibration graph was obtained for 0.1-15 mg l(-1) of Co(II) with a correlation coefficient value of 0.995 for Co-BSOPD complex. Large excess of 44 cations, anions and complexing agents do not interfere in the determination. The method was successfully used in the determination of cobalt(II) from synthetic mixture and certified reference materials for the purpose of validating the method and the results of analyses were found to be excellent agreement with those of actual values. This developed method was also used for determination of cobalt in some environmental waters (potable and polluted), biological (blood and urine) and soil samples and solution containing both cobalt(II) and cobalt(III). The results of the proposed method for biological samples were comparable with AAS and were found to be in good agreement. The method has high precision and accuracy (s=+/-0.01 for 0.5 mg l(-1)).