Separation and screening of short-chain chlorinated paraffins in environmental samples using comprehensive two-dimensional gas chromatography with micro electron capture detection

Short-chain chlorinated paraffins (SCCPs) are highly complex technical mixtures with thousands of isomers and numerous homologs. They are classified as priority candidate persistent organic pollutants under the Stockholm Convention for their persistence, bioaccumulation, and toxicity. Analyzing SCCPs is challenging because of the complexity of the mixtures. Chromatograms of SCCPs acquired using one-dimensional (1D) gas chromatography (GC) contain a large characteristic “peak” with a broad and unresolved profile. Comprehensive two-dimensional GC (GC×GC) shows excellent potential for separating complex mixtures. In this study, GC×GC coupled with micro electron capture detection (μECD) was used to separate and screen SCCPs. The chromatographic parameters, including the GC column types, oven temperature program, and modulation period, were systematically optimized. The SCCP congeners were separated into groups using a DM-1 column connected to a BPX-50 column. The SCCP congeners in technical mixtures were separated according to the number of chlorine substituents for a given carbon chain length and according to the number of carbon atoms plus chlorine atoms for different carbon chain lengths. A fish tissue sample was analyzed to illustrate the feasibility of the GC×GC–μECD method in analyzing biological samples. Over 1,500 compounds were identified in the fish extract, significantly more than were identified using 1D GC. The detection limits for five selected SCCP congeners were between 1 and 5 pg/L using the GC×GC method, and these were significantly lower than those achieved using 1D GC. This method is a good choice for analysis of SCCPs in environmental samples, exhibiting good separation and good sensitivity. Graphical Abstract

Chromatograms of a technical C10–C13 SCCP mixture with a 55 % (w/w) chlorine content obtained using a gas chromatography–electron capture detection (ECD) and b GC×GC–μECD     

Group separation of organohalogenated compounds by means of comprehensive two-dimensional gas chromatography

Separations of 12 compound classes, polychlorinated biphenyls (PCBs), diphenyl ethers (PCDEs), naphthalenes (PCNs), dibenzothiophenes (PCDTs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), terphenyls (PCTs) and alkanes (PCAs), toxaphene, organohalogenated pesticides (OCPs), and polybrominated biphenyls (PBBs) and diphenyl ethers (PBDEs) by comprehensive two-dimensional gas chromatography were evaluated. Five column combinations, DB-1 x 007-210, DB-1 x HT-8, DB-1 x LC-50, DB-1 x 007-65HT and DB-1 x VF-23ms were used to study, primarily, group-type separations, but attention was devoted also to within-class separation, especially for those classes which were not addressed in much detail before, the PCNs, OCPs, PBBs and PCTs. The DB-1 x 007-210 column set did not offer any extra separation compared to one-dimensional GC. For the DB-1 x HT-8 column combination, the useful principle of congener separation on the basis of number of halogen substituents in a molecule was confirmed (PCBs, toxaphene) and extended (PCTs, PBDEs). No practically useful group-type separation was observed for this column combination. The DB-1 x LC-50 set provides group separation based on planarity: planar compounds such as PCDDs, PCDFs, PCDTs and PCNs are much more retained than, and therefore separated from, non-planar analytes. Within the classes of PCBs, PBBs and PCTs highly useful separation of planar from non-planar compounds was also observed. The DB-1 x 007-65HT column set effectively separates PCAs and PBDEs from all other compound classes, and provides a good separation of brominated and chlorinated analogue classes from each other. This column set was the most efficient one for within-class separation of OCPs and PCNs. Finally, DB-1 x VF-23ms yields excellent within-class separations, especially of non-aromatic compounds, viz. OCPs, toxaphene and PCAs. No group separation was observed here. The applicability of the approach was demonstrated for a sediment extract and a dust extract. In the sediment extract, PCDDs, PCDFs, PCAs and PCNs were identified and their efficient separation was achieved. In the dust sample, separation of PCAs and PBDEs was achieved and several new PBDE congeners were identified.     

High-resolution separation of polychlorinated biphenyls by comprehensive two-dimensional gas chromatography

Comprehensive two-dimensional gas chromatography (GC x GC) with micro electron-capture detection (microECD) has been optimised for the separation of polychlorinated biphenyl congeners with emphasis on the separation of 12 toxic non- and mono-ortho chlorinated biphenyls (CBs), viz. CBs 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169 and 189. The selection of the first- and second-dimension columns and the temperature programme optimisation were carried out with a mixture of 90 CBs and the results are compared with those of one-dimensional GC. A complete separation of all 12 priority CBs was obtained with two column combinations, HP-1-HT-8 and HP-1-SupelcoWax-10. With the HP-1-HT-8 column set, ordered structures show up in the two-dimensional plane, with the number of chlorine substituents and their position (ortho vs. non-ortho) being the main parameters of interest. This can help with congener identification. Estimated detection limits are excellent, i.e. about 10 fg. To illustrate the potential and the versatility of GC x GC-microECD, a cod liver extract and a standard mixture of the 17 most toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans together with 90 CBs were analysed as an application.     

Partial structure elucidation of the most abundant octa and nonachlorotoxaphene congeners in marine mammals by using conventional electron ionization mass spectrometry and mass spectrometry/mass spectrometry

Summary Conventional electron ionization (EI) mass spectrometry (MS) and MS/MS techniques were applied to the analysis of two abundant octa and nonachlorobornanes isolated from seals of the Baltic sea and originating from technical toxaphene. The exact sterical structures of the two compounds were previously determined using nuclear magnetic resonance (NMR) spectroscopy by two independent research groups. The MS and MS/MS data generated in this study allowed partial structure elucidation of these polychlorobornanes, in particular revealing the distribution of the Cl substituents between the six-membered carbon ring, the bridge and the bridgehead in the parent bornane structure. Fragmentation of the six-membered carbon ring and the bridge by retro-Diels-Alder (RDA) and related mechanisms was discovered by studying specific parent/daughter ion transitions. The detailed fragmentation pathways formulated may be applicable to the structure elucidation of other toxaphene congeners and the monitoring of strategic transitions is highly selective for the detection of these compounds in technical toxaphene and in environmental samples.     

Separation of 26 toxaphene congeners and measurement in air particulate matter SRMs compared to technical toxaphene SRM 3067

Toxaphene is a complex technical mixture that has been found ubiquitously in the environment but has caused issues for analysis, especially of individual congeners. This paper reports the elution order of 26 major toxaphene congeners on three gas chromatographic columns. The three different stationary phases generally had similar elution orders for the toxaphene congeners, but fewer co-elutions occurred on a low-bleed, low-polarity column. These congeners (except for two that co-eluted and were not added to the calibration mixture) were examined in air particulate matter standard reference materials (SRMs), 1648a, 1649a, and 1649b as well as SRM 3067 toxaphene in methanol for assignment of reference values. SRM 3067 had mass fractions an order of magnitude greater than the air particulate SRMs, which ranged from 0.568 ± 0.018 ng g⁻¹ dry mass (B9-2006 in SRM 1648a) to 12.9 ± 0.20 ng g⁻¹ dry mass (B9-715 (P 58) in SRM 1649a). The three air particulate SRMs all had different mass fractions and proportions of congeners relative to the sum of the toxaphene congeners. SRM 3067 may be useful as a technical mixture toxaphene congener calibrant. SRMs 1648a and 1649b will serve as reference materials for the analysis of 21 (three congeners were not included due to values below the detection limit or a potential polychlorinated biphenyl co-elution) toxaphene congeners in atmospheric particulate samples.     

气相色谱-负化学电离质谱法测定沉积物和鱼肉中毒杀芬的8个同类物及其总含量

建立了气相色谱-负化学电离源质谱测定沉积物和鱼肉中毒杀芬的8个同类物及其总量的分析方法。样品由二氯甲烷在加速溶剂萃取仪上提取,经铜粉(或凝胶渗透色谱)及硅胶和氧化铝复合柱净化,使用DB-XLB柱分离,在选择离子检测模式下同时检测毒杀芬的8个同类物及其总量。多氯联苯(PCB)的氧反应水平由内标PCB204监测,并保持在低于1%。使用平均相对响应因子定量:采用单个离子的峰面积对8个毒杀芬同类物进行定量,采用可检测到的毒杀芬同类物峰面积的和对毒杀芬总量进行定量。单个同类物的校正标准溶液质量浓度范围是0.5 (P62为5)~500 μ g/L,毒杀芬总量的校正标准溶液质量浓度范围是50~500 μ g/L。以最低校正标准溶液的浓度为最低定量浓度。同类物的日间平均回收率是(90.8±17.4)%(n=10),日间测定的相对标准偏差为5.4%~12.8%(n=10),显示了本方法有较高的准确性和精确性。应用该方法分析了沉积物和鱼肉中毒杀芬的含量。     

Liquid chromatographic profiles of individual compounds of technical toxaphene

The elution orders of 20 hexa- to nonachlorobornanes and five hexa- to octachlorocamphenes were studied with normal-phase silica and amino phase HPLC, reversed-phase HPLC, as well as gel-permeation chromatography (GPC). Twenty-one compounds of technical toxaphene (CTTs) are commercially available and four were isolated from environmental samples. Structure-activity relationships and chromatographic properties were deduced from the data sets derived on these LC systems. The retention on silica (low-resolution LC and HPLC) increased with the polarity of the CTTs. The elution order of CTTs on amino normal-phase HPLC was, for the most part, the same as on silica normal-phase HPLC. The degree of chlorination determined the elution order of CTTs on C18 RP-HPLC. CTTs eluted from medium-pressure GPC with decreasing molecular size. Chlorobornanes with dichloro substituents on the six-membered ring eluted after the chloroboranes without geminal chlorine atoms on secondary carbons, indicating that these congeners are larger. Altogether, the results increase the knowledge of complex substance class and may serve as a tool in order to gain further standard components.     

Separation of technical 4-nonylphenols and their biodegradation products by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry

Comprehensive two-dimensional gas chromatography (GC x GC) coupled to time-of-flight mass spectrometry (TOF-MS) was applied to improve the separation of 4-nonylphenol isomers and their biodegradation products. The structurally similar nonylphenol isomers were separated by combining a 30 m long semi-polar column and a short polar capillary. Both were coupled via a custom-made liquid nitrogen cryogenic modulator. The advanced GC resolution of coeluting isomers, additionally supported by fast scanning TOF-MS, provided clearer, non-interfered mass spectra of individual isomers. Thus, identification of components is facilitated as shown for isomeric 4-nonylphenols and metabolites of their biodegradation by Clavariopsis aquatica, an aquatic fungus. GC x GC-TOF-MS analysis enabled the separation of about 40 alkylphenol isomers included in technical 4-nonylphenol. During biodegradation the variety of emerging compounds increased with longer reaction time. The comprehensive analysis indicated a broad spectrum of hydroxylated, carboxylated nonylphenolisomers and additionally, chlorinated aromatic compounds produced and released from the fungal culture.     

Offline coupling of high-speed counter-current chromatography and gas chromatography/mass spectrometry generates a two-dimensional plot of toxaphene components

High-speed counter-current chromatography (HSCCC), a separation technique based solely on the partitioning of solutes between two immiscible liquid phases, was applied for the fractionation of technical toxaphene, an organochlorine pesticide which consists of a complex mixture of structurally closely related compounds. A solvent system (n-hexane/methanol/water 34:24:1, v/v/v) was developed which allowed to separate compounds of technical toxaphene (CTTs) with excellent retention of the stationary phase (S_f = 88%). Subsequent analysis of all HSCCC fractions by gas chromatography coupled to electron-capture negative ion mass spectrometry (GC/ECNI-MS) provided a wealth of information regarding separation characteristics of HSCCC and the composition of technical toxaphene. The visualization of the large amount of data obtained from the offline two-dimensional HSCCC–GC/ECNI-MS experiment was facilitated by the creation of a two-dimensional (2D) contour plot. The contour plot not only provided an excellent overview of the HSCCC separation progress, it also illustrated the differences in selectivity between HSCCC and GC. The results of this proof-of-concept study showed that the 2D chromatographic approach involving HSCCC facilitated the separation of CTTs that coelute in unidimensional GC. Furthermore, the creation of 2D contour plots may provide a useful means of enhancing data visualization for other offline two-dimensional separations.     

Polybrominated diphenyl ether congeners and toxaphene in selected marine standard reference materials

Polybrominated diphenyl ether (PBDE) congeners and components of the complex mixture toxaphene are stable in the environment and readily bioaccumulated into wildlife and human tissues. PBDEs are presently used in large quantities worldwide as flame retardants in textiles, furniture, computer equipment, and cables. Toxaphene is a complex mixture of chlorinated bornanes and bornenes that was the most heavily used pesticide in the United States until it was banned in 1982; however, some countries continue to use toxaphene. The National Institute of Standards and Technology has quantified PBDE congeners and toxaphene in several available Standard Reference Materials (SRMs) using methods of gas chromatography with electron impact mass spectrometry (GC-EI-MS) and GC negative chemical ionization (NCI) MS, respectively. SRM 1588a Organics in Cod Liver Oil and SRM 1945 Organics in Whale Blubber were examined for PBDE congeners 47, 99, 100, 153, and 154, total toxaphene, and toxaphene congeners 26, 50, and 62. SRM 1946 Lake Superior Fish Tissue was also examined for total toxaphene and toxaphene congeners. The sum of the PBDE congeners (mean, (1 SD) wet basis) for SRM 1945 was 150 ng g^–1 (7 ng g^–1). The concentration of PBDE 47 in SRM 1588a was 82.7 ng g^–1 (2.8 ng g^–1). Other PBDEs were detected in SRM 1588a but were not quantified due their low levels. The total toxaphene (wet mass basis) was 1,210 ng g^–1 (127 ng g^–1), 1,960 ng g^–1 (133 ng g^–1), and 3,980 ng g^–1 (248 ng g^–1) in SRMs 1945, 1946, and 1588a, respectively. The values for PBDEs and toxaphene determined in the SRMs, while not certified, indicate that the SRMs will be suitable control materials for PBDE and toxaphene analyses.     

Characterization and pattern recognition of oil-sand naphthenic acids using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

Oil-sand naphthenic acids (NAs) are organic wastes produced during the oil-sand digestion and extraction processes and are very difficult to separate and analyze as individual components due to their complex compositions. A comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GC x GC/TOF-MS) system was applied for the characterization of two commercial mixtures of naphthenic acids (Fluka and Acros) and a naphthenic acid sample extracted from the Syncrude tailings. Contour plots of chromatographic distributions of different Z homologous series of the Fluka, Acros and Syncrude NAs were constructed using fragment ions that were characteristic of the NA's molecular structures. Well-ordered patterns were observed for NAs of Z= 0 and -2 which corresponded to acyclic acids and monocyclic acids, respectively. For NAs of Z= -4, -6, and -8, specific zones were observed which would allow the pattern recognition of these NAs obtained from different origins. As expected, gas chromatographic retention times increase with the number of the carbons and the number of rings in the molecules. Little signal was obtained for NAs with Z numbers of -10, or lower. Deconvoluted mass spectra of various NA isomers were derived from the reconstructed GC x GC chromatogram, permitting detailed structural elucidations for NAs in the future. The current study demonstrated that the combination of GC x GC and the TOF-MS is a powerful to identify origins of the NAs in an effective manner. GC x GC/TOF-MS alone, however, may not be enough to characterize each individual isomer in a complex mixture such as NAs. The use of mass deconvolution software followed by library search have thus become necessary to separate and study the mass spectrum of each individual NA component, allowing a detailed identification of the toxic components within the NAs mixture.     

Improved determination of flavour compounds in butter by solid-phase (micro)extraction and comprehensive two-dimensional gas chromatography

The practicability and potential of comprehensive two-dimensional gas chromatography (GC x GC) coupled to both conventional flame ionisation (FID) and time-of-flight mass spectrometric (TOF-MS) detection, were compared with those of conventional one-dimensional (1D) GC, with the determination of flavour compounds in butter as an application. For polar flavour compounds, which were collected from the aqueous fraction of butter by means of solid-phase extraction (SPE), it was found that GC x GC dramatically improves the overall separation. Consequently, quantification and preliminary identification based on the use of ordered structures, can be performed more reliably. The improvement effected by replacing 1D-GC by GC x GC is considerable also in the case of TOF-MS detection, as illustrated by the high match factors generally obtained during identification. GC x GC was also used successfully for the characterisation of volatile flavour compounds in the headspace of butter collected by solid-phase microextraction (SPME) and to study the effect of heat treatment on the composition of butter samples in more detail.     

Quantitation of camphechlor/toxaphene in cod-liver oil by integration of the HRGC/ECD-pattern

Summary Quantitation of camphechlor/toxaphene in biological matrices like cod-liver oil or fish is difficult because it is a very complex mixture of alicyclic polychlorinated compounds. Furthermore, many toxaphene components are biotransformed and photodegraded and the complex mass spectral fragmentation pattern of HRGC/MSD (electron impact (EI)) cannot be used for quantitation at the g/g-level or below. The use of several indicator-peaks after ECD-detection using the technical standard mixture for calibration does not characterize the entire pattern in a biological sample. Two averaging integration methods that are based on the entire HRGC/ECD-pattern of toxaphene compounds after separation from the PCB congeneres by adsorption chromatography on silicagel, allow a fast and accurate quantitation of the mixture in biological samples, e.g. cod-liver oil. Biological degradation does not disturb the determination because the whole pattern of the complex mixture is considered instead of only a few compounds of the parent mixture which could be degraded or not.     

Comprehensive two-dimensional gas chromatography of the 209 polychlorinated biphenyls

Comprehensive two-dimensional gas chromatography (GC x GC) of the 209 polychlorinated biphenyls (CBs) was carried out using a longitudinally modulated cryogenic system (LMCS) and liquid carbon dioxide as cryogen. The effluent from a non-polar column was modulated and further separated on either a polar or a shape-selective second-dimension column. Five GC x GC column combinations were evaluated, with DB-XLB as the first column in each case. DB-XLB separates more congeners than any other GC column currently available. When combined with a biscyanopropyl siloxane (SP-2340 or BPX70) or smectic liquid crystal (LC-50) second-dimension column in a GC x GC system many additional CBs can be separated. In total, 176 and 181 of the 209 congeners were separated (Rs = 0.5) on the column combinations DB-XLB/SP-2340 and DB-XLB/LC-50, respectively. Of the 136 CBs present in any Aroclor mixture at concentrations greater than 0.05% (w/w), 126 were resolved using either of these two column combinations. The seven frequently measured CBs 28, 52, 101, 118, 138, 153, 180, and the WHO-PCBs 77, 81, 105, 114, 118, 123, 126, 156. 157, 167, 169 and 189 were all separated from Aroclor CBs on the DB-XLB/LC-50 column set, whereas CBs 118 and 131 coeluted on the DB-XLB/SP-2340 column set. In addition, three technical CB formulations (Aroclors 1232, 1248 and 1260) and a seal blubber sample (Halichoerus grypus) from the Baltic Sea were analyzed. Similar peak patterns were found for Aroclor 1260 and the CBs in the seal blubber, facilitating use of this technical CB formulation to identify the CBs in the blubber by GC x GC. Individual CBs in environmental samples, such as seal blubber, may be identified semi-automatically by matching the samples GC x GC profiles to a template generated using a standard containing all 209 CBs. Using such a template, 64 CBs were identified in the grey seal blubber sample.     

同位素稀释-气相色谱-串联质谱法测定土壤中的指示性毒杀芬

建立了土壤样品中指示性毒杀芬Parlar No.26 (P26)、Parlar No.50 (P50)和Parlar No.62 (P62)的同位素稀释-气相色谱-串联质谱(ID-GC-MS/MS)的分析方法。土壤样品使用压力溶剂萃取装置(PLE)提取,以丙酮-正己烷(1:1, v/v)混合溶液为提取溶剂;提取液依次经由多层酸性硅胶柱和活化硅胶柱净化;洗脱液经氮吹浓缩至20 μL后,利用GC-MS/MS的多反应监测(MRM)模式进行定性和定量。结果表明本方法可对样品中的P26、P50和P62进行分析,相对标准偏差(RSD)小于11%,回收率可以达到55%～110%;P26、P50和P62的仪器检出限分别为3.0、3.0和6.0 pg。将该方法用于某地区农田表层土壤中3种指示性毒杀芬的检测,其中P26的含量为0.17 ng/g、P50为0.08 ng/g、P62为0.09 ng/g。此方法适用于土壤样品中指示性毒杀芬的分析。     

全二维气相色谱-电子捕获检测器法分析土壤中毒杀芬同类物的残留

建立了全二维气相色谱-电子捕获检测器(GC× GC-μECD)检测土壤中毒杀芬同类物的分析方法.以非极性的DB- XLB(20 m×0.25 mm×0.25 μm)为第一色谱柱,中等极性的BPX-50(2 m×0.1 mm×0.1 μm)为第二色谱柱,对土壤中23种高关注毒杀芬同类物进行了分离鉴定,并采用基质曲线外标法进行定量分析.本方法在1～200,μg/L浓度范围内,毒杀芬同类物的线性相关系数(r2)均大于0.99,方法检出限(S/N=3)为0.039～0.482 μg/L,基质加标毒杀芬同类物的回收率为55％～115％,相对标准偏差(RSD)均小于30％(n=5).利用本方法对毒杀芬污染的土壤样品进行了测定,获得了较好的分离效果.     

Global and selective detection of organohalogens in environmental samples by comprehensive two-dimensional gas chromatography-tandem mass spectrometry and high-resolution time-of-flight mass spectrometry

We successfully detected halogenated compounds from several kinds of environmental samples by using a comprehensive two-dimensional gas chromatograph coupled with a tandem mass spectrometer (GC×GC-MS/MS). For the global detection of organohalogens, fly ash sample extracts were directly measured without any cleanup process. The global and selective detection of halogenated compounds was achieved by neutral loss scans of chlorine, bromine and/or fluorine using an MS/MS. It was also possible to search for and identify compounds using two-dimensional mass chromatograms and mass profiles obtained from measurements of the same sample with a GC×GC-high resolution time-of-flight mass spectrometer (HRTofMS) under the same conditions as those used for the GC×GC-MS/MS. In this study, novel software tools were also developed to help find target (halogenated) compounds in the data provided by a GC×GC-HRTofMS. As a result, many dioxin and polychlorinated biphenyl congeners and many other halogenated compounds were found in fly ash extract and sediment samples. By extracting the desired information, which concerned organohalogens in this study, from huge quantities of data with the GC×GC-HRTofMS, we reveal the possibility of realizing the total global detection of compounds with one GC measurement of a sample without any pre-treatment.     

Gas chromatography/multiphoton ionization/time-of-flight mass spectrometry of polychlorinated biphenyls

A sample mixture of polychlorinated biphenyls (PCBs) was measured by gas chromatography/multiphoton ionization/time-of-flight mass spectrometry (GC/MPI/TOF-MS) using four types of laser sources. When a fourth harmonic emission (266 nm) of a picosecond Nd:YAG laser (1064 nm) was utilized, highly chlorinated PCBs larger than hepta-CBs were not observed. A fifth harmonic emission (213 nm) of the picosecond Nd:YAG laser allowed the measurement of PCBs from di-CBs to octa-CBs, and the limit of detection (LOD) was several pg for each component of PCBs. The LOD for the total amount of PCBs, which was calculated using the protocol provided by the Ministry of the Environment, Japan, was 1000 pg. The signal intensity of the congeners with chlorine atoms at the ortho positions (non-coplanar PCBs) was enhanced by using the fifth harmonic emission. When the fourth harmonic emission remaining after fifth harmonic generation was simultaneously used, the LOD for total PCBs was improved to 667 pg. The PCB sample was also measured using a third harmonic emission (267 nm) of a femtosecond Ti:sapphire laser (800 nm), providing an LOD of 677 pg. Thus, the two-color beam (266/213 nm) of a picosecond Nd:YAG laser had a comparable, or even slightly superior, performance to the more expensive femtosecond Ti:sapphire laser.     

Using new structurally related additive schemes in the precalculation of gas chromatographic retention indices of polychlorinated hydroxybiphenyls on HP-5 stationary phase

A new additive scheme is proposed for the precalculation of gas chromatographic retention indices of complex organic compounds. The principal feature of this approach is the absence of previously calculated I increments for any structural fragments or functional groups in the molecule. Instead, arithmetical operations involving I values of simpler structural analogues of target compounds are used directly. I precalculation for polychlorinated hydroxybiphenyls (839 congeners) on the HP-5 stationary phase was chosen as one of the most important applications of the method under discussion. Such a large number of congeners cannot be obtained as reference samples and their gas chromatographic (GC)-mass spectrometric (MS) identification should therefore be based currently on precalculated I values.     

Congener specific determination of compounds of technical toxaphene (CTTs) in different antarctic seal species

Summary Gas chromatography and electron-capture, negative-ionization, mass spectrometry (GC-ECNI-MS) in combination with a non-polar stationary phase (CP-Sil 2) was applied to study the composition of residues of the multicomponent toxaphene mixture in seal blubber from the Antarctic. In samples of the five Antarctic seal species eleven compounds of technical toxaphene (CTTs) were detected and six of them quantified by application of single standard compounds. Five abundant CTTs in seal blubber were included in the “Parlar 22 components standard” (commercially available) and one further was isolated and quantified for the first time. Finally, high levels of toxaphene were determined in Weddell seals and crabeaters confirming that toxaphene is a major organochlorine pollutant in the Antarctic.