Toxaphene In Environmental Samples Research Articles

Determining indicator toxaphene congeners in soil using comprehensive two-dimensional gas chromatography–tandem mass spectrometry

Toxaphene, which is a broad spectrum chlorinated pesticide, is a complex mixture of several hundred congeners, mainly polychlorinated bornanes. Quantifying toxaphene in environmental samples is difficult because of its complexity, and because each congener has a different response factor. Toxaphene chromatograms acquired using one-dimensional gas chromatography (1DGC) show that this technique cannot be used to separate all of the toxaphene congeners. We developed and validated a sensitive and quantitative method for determining three indicator toxaphene congeners in soil using an isotope dilution/comprehensive two-dimensional gas chromatography-tandem mass spectrometry (GC × GC-MS). The samples were extracted using accelerated solvent extraction, and then the extracts were purified using silica gel columns. (13)C₁₀-labeled Parlar 26 and 50 were used as internal standards and (13)C₁₀-labeled Parlar 62 was used as an injection standard. The sample extraction and purification treatments and the GC × GC-MS parameters were optimized. Subsequently the samples were determined by GC × GC-MS. The limits of detection for Parlar 26, 50, and 62 were 0.6 pg/g, 0.4 pg/g, and 1.0 pg/g (S/N=3), respectively, and the calibration curves had good linear correlations between 50 and 1000 μg/L (r(2)>0.99). Comprehensive two-dimensional GC gave substantial improvements over one-dimensional GC in the toxaphene analysis. We analyzed soil samples containing trace quantities of toxaphene to demonstrate that the developed method could be used to analyze toxaphene in environmental samples.

The effect of co-occurring polychlorinated biphenyls on quantitation of toxaphene in fish tissue samples by gas chromatography negative ion mass spectrometry

Determinative methods based on gas chromatography-negative chemical ionization mass spectrometry (GC–NCI/MS) provide improved sensitivity and specificity for toxaphene in environmental samples, but are subject to misidentification due to oxygen reaction in the presence of polychlorinated biphenyls (PCBs). The goal of this study was to quantify the impact of co-occurring PCBs in fish tissue samples when utilizing single quadrupole instruments to implement this method. Mixtures of PCB congeners and technical toxaphene, and extracts of fish tissue with varying concentrations of PCBs were analyzed for individual congener and total toxaphene concentrations by GC–NCI/MS. The contribution of co-injected PCB 204 ranged from 23% to 88% of the total peak area for the Cl-9 toxaphene homolog quantitation ion, a contribution that increased as the ratio of technical toxaphene to PCB 204 decreased. PCB interferences in fish tissue extracts, including a standard reference material, were subtracted using a three-step procedure featuring spectral analysis of isotopic patterns for target peaks. Total toxaphene concentrations without PCB subtraction in three fish tissue samples with low, intermediate and high co-occurring PCBs were overestimated by 33, 55 and 745%, respectively, underscoring the need for practical strategies to account for PCB interferences in GC–NCI/MS based protocols. In contrast, no appreciable interference or resulting positive bias in concentrations was observed for quantitation of eight common toxaphene residue congeners.

The determination of toxaphene in environmental samples by negative ion electron capture high resolution mass spectrometry

A method is described for the analysis of toxaphene in environmental samples by high resolution gas chromatography high resolution mass spectrometry in selected ion electron capture negative ion mode. Toxaphene is detected by monitoring [M–Cl] −fragments ions of chlorobornanes (Cl 6–Cl 10) and chlorobornenes (Cl 6–Cl 7) using formal ion ratio criteria. The method shows high sensitivity and excellent specificity for the detection of chlorobornanes with negligible interference from of a wide range of common environmental organochlorines including chlordanes, PCBs and PCB-oxygen adducts. The analytical scheme is applicable to sediment and biological tissue samples and typically provide sample detection limits of less than 0.2 ng/g technical toxaphene for a 10 g sample.

The application of standard methods for the determination of toxaphene in environmental media

In the United States, it is necessary to analyze for toxaphene using approved, validated methods acceptable to the regulatory agencies. As a result of an interlaboratory study and technical exchanges among the US EPA Region IV (EPA), the State of Georgia Environmental Protection Division (EPD), and Hercules Incorporated, guidelines for the application of SW-846 Method 8080 were developed. Results of analyses for sludge, soil, and water samples agreed within a percent relative standard deviation (% RSD) range of 6.9–20%. Through continued technical interchanges, guidance for the application of SW-846 Method 8081 has been developed. The results of analyses of fourteen split samples of soil and sediment produced a percent relative standard deviation that ranged from 1.6% to 127%, with an average of 38%. When two unusually divergent results were removed from consideration, the average % RSD reduced to 26%. The results of analyses of split samples show agreement between the EPA laboratory and a Hercules contract laboratory. Therefore, the guidance has achieved its purpose of producing agreement among data from different laboratories so that data reviewers may have assurance that the analytical method has been applied correctly and consistently for the determination of toxaphene in environmental samples.

Studies of toxaphene in technical standard and extracts of background air samples (Point Petre, Ontario) using multidimensional gas chromatography–electron capture detection (MDGC–ECD)

MDGC–ECD procedures have been used to provide insight into the compositional complexity of some of the specific peaks or clusters observed in the gas chromatographic analysis of a technical toxaphene standard, with reference to individual toxaphene congeners (Parlar # components) that are now commercially available. These investigations have focussed initially upon those peaks and clusters recently identified (Shoeib, M., Brice, K.A., Hoff, R., 1999. Chemosphere 39, 849–871) as dominant constituents of background ambient air. Multiple electron-capturing components have been found to be present in all the species studied: the available individual toxaphene congeners have been matched against these components where possible. In similar fashion, the responses obtained in equivalent gas chromatographic elution windows from the analysis of typical processed air sample extracts have been investigated, with the results showing clear differences relative to the patterns found in the technical toxaphene standard. In most cases, the air sample shows reduced complexity with fewer components present in the cluster. Also, the presence of interfering responses (due to PCBs and other organochlorines) is quite apparent and significant, showing that major problems and errors could arise when using single-column GC–ECD procedures for quantitation of toxaphene in environmental samples. The presence of certain of the Parlar species in the air samples has been confirmed and in most cases these represent the dominant toxaphene component found in the targeted cluster. Furthermore, the persistence of certain congeners in the atmospheric samples appears to be strongly dependent upon chemical structure, since the congeners in question possess an alternating exo–endo chlorine substitution pattern around the six-membered ring in the bornane skeleton. Such persistence is probably the result of lower metabolization of toxaphene residues in soils, water and sediments leading to a similar pattern in the atmosphere following volatilization.

Determination of toxaphene in biological samples using high resolution GC coupled with ion trap MS/MS

Toxaphene remains as a pollutant of global concern because of its persistence in the environment. Its complex combination of congeners and the lack of individual standards makes accurate measurement of toxaphene residues in environmental samples a challenge. We have developed a novel method to measure toxaphene in environmental samples using ion trap MS/MS. Adequate sensitivity for analysis of biological samples such as fish and marine mammal blubbers were achieved (around 0.02 ppb to 0.06 ppb for individual congeners and 5.6 ppb for toxaphene mixtures). Accuracy was demonstrated by good recoveries of spiked toxaphene in corn oil samples (102% for toxaphene congeners at 4 ppb and 96% for toxaphene mixture at 139 ppb level). Results of analysis of toxaphene in cod liver oil (NIST SRM 1588) using the MS/MS method compared favorably with the median round robin interlaboratory data. The major advantage of the ion trap MS/MS over the existing methods; electron capture negative ionization mass spectrometer or electron capture detector, is its excellent selectivity. Interference from other organochlorines can virtually be eliminated. Therefore, the developed MS/MS method can be used as a reliable alternative to high resolution mass spectrometer for measurement of toxaphene in environmental samples with relatively low cost instrumentation.

Toxaphen in der Umwelt

Residue analysis of toxaphene has been difficult because of the complexity of the technical mixture consisting of a high number of compounds with very similar structure and differing chlorine content. Furthermore, the composition of toxaphene in environmental samples varies widely and is normally not related to that of the technical mixture. Therefore, quantification of single components in environmental samples was impossible. After the isolation and identification of a great number of components during the last decade, enough standards are available for the reliable quantification of toxaphene in all environmental compartments. Recently, most research has been performed on the separation of chiral components of toxaphene with a view to identifying the degradation mechanisms and distribution pathways.

The quantification of toxaphene in environmental samples

A simplified analytical method is described for the determination of toxaphene in environmental samples by electron capture negative ion GC/MS using internal standards. The method allows toxaphene to be determined at the low ppb level in the presence of PCBs for a variety of sample matrices including sediment and biological tissue. Toxaphene is quantified from the total peak area response for 21 prominent components using mass chromatograms of the characteristic polychlorobornane [M-Cl] − ions. The quantitation method shows minimal interference from PCB congeners, or from compounds in the chlordane group. Performance was evaluated using a cod liver oil NIST 1588 standard reference material. The effect of oxygen pressure on PCB interference and toxaphene quantitation is discussed.

Ein Beitrag zur Quantifizierung von Toxaphenr�ckst�nden in Fisch�len

When quantified by HPGC-ECD and HPGC-NCI-SIM commercially available standards of the insecticide Toxaphene show different detector responses, primarily depending on the percentage of chlorine in the mixtures. To obtain accurate results, residues of Toxaphene in environmental samples should be quantified by using a standard with a similar or nearly similar detector response. If this is not possible, any standard may be used but the results of the samples must be corrected afterwards. By comparing different integration methods, it can be seen that the best results are obtained by integrating as many single-peak areas as possible. Quantification by integration of the bulge formed by raising the baseline, which can be observed in many gas chromatograms of Toxaphene standards, should be avoided because this hump is caused by degradation of chlorobornanes under higher temperatures. The extent of this bulge depends both on temperature and the percentage of chlorine, the latter being generally lower in the samples as a result of transformation processes under environmental conditions. Therefore integration of the bulge or the whole area leads to lower results.

Sunlight photochlorination and dark chlorination of monoterpenes

The aqueous chlorination of the monoterpenes camphene, limonene, α-pinene and β-pinene produced complex polychlorinated product mixtures. The extent of chlorination was primarily dependent on pH and light conditions. At pH2 and exposure to sunlight, product mixtures were obtained that had striking similarities to Toxaphene. At higher pH or in the dark, less extensive but still substantial chlorination took place; these lower chlorinated compounds could be mistaken for biologically degraded Toxaphene in environmental samples.

Quantitation of toxaphene in environmental samples using negative ion chemical ionization mass spectrometry

A method for quantitating toxaphene in environmental samples using methane negative ion chemical ionization (NICI) mass spectrometry in the selected ion mode is given. NICI is highly selective and sensitive for measuring toxaphene. This method monitors ions from each of the homologue groups in the toxaphene mixture having 6 to 10 chlorines corresponding to the M/sup -/ or the (M - Cl)/sup -/ ion clusters (m/z 340, 341, 342, 343, 375, 377, 411, 413, 447, 449). Additional ions are monitored to correct for interferences from chlorinated pesticides (m/z 336, 338, 371, 373, 376, 412, 444, 448). Quantitation is done relative to an internal standard, 2,2',3,4,4',5,6,6'-octachlorobiphenyl (m/z 428 and 430). The NICI response was linear over 4 orders of magnitude, and the detection limit was 75 pg. This method is accurate and reproducible for measuring toxaphene in the presence of a major interferent, technical chlordane. The method is successful at measuring toxaphene in complex environmental matrices such as fish, and it can also be used to evaluate the changes in the relative homologue distribution that may have resulted from environmental transformations.

A note on toxaphene in environmental samples from the Chesapeake Bay region

A note on toxaphene in environmental samples from the Chesapeake Bay region