Enantiomeric resolution of persistent compounds of technical toxaphene (CTTs) on t-butyldimethylsilylated β-cyclodextrin phases

Summary Eight of the most important single compounds of technical toxaphene were separated on t-butyldimethylsilylated β-cyclodextrin (β-BSCD) diluted in a medium polar phase using gas chromatography with electron capture detectors (GC-ECD). The enantiomeric resolution of all compounds was obtained in one GC run. The β-BSCD phase also separated the enantiomers of oxychlordane, cis- and trans-chlordane as well as α-HCH. Problems in the enantioselective determination of CTTs in biological samples are discussed. Finally, the enantioselective determination of the two most recalcitrant CTTs in biological samples was achieved using electron capture negative ionization mass spectrometry (GC-ECNI-MS) in the single ion monitoring (SIM) mode. Presented at the 21^st ISC held in Stutgart, Germany, 15^th–20^th September, 1996.     

Optimized pressure-pulse splitless injection and electron-capture, negative ionization detection for the congener specific determination of compounds of technical toxaphene

The goal of the study is the optimization of the congener specific determination of compounds of technical toxaphene (CTTs). For this reason GC/ECNI-MS and CTT standard mixtures are applied. The splitless injection is improved by pressure-pulse injection which yields significantly higher abundance of the CTTs than by the conventional constant flow injection technique. The abundance of low volatile CTTs like B9-1025 (Parlar #62) is increased by factor 3 or more. The pressure-pulse injection can easily be integrated in standard (constant flow splitless injection) methods without influencing the retention times and reproducibility. The GC oven program and the flow are optimized for the separation of CTTs on a non-polar CP-Sil 2 column. Problems caused by oxygen in the ion source are discussed.     

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.     

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.     

Persistent Organic Pollutants in Baikal Seal ( Pusa sibirica ) Blubber

The concentrations of persistent organic pollutants in the blubber of Baikal seal were determined. The data obtained over the period from 1997 to 2017 are considered. The revealed changes in the concentrations of PCBs and DDT and its metabolites demonstrate the complexity of the redistribution processes of these compounds. The total concentration of POPs in Baikal seal blubber has not diminished over the past 20 years (1997–2017) and is close to the levels in 1993 and 1981.     

Marine mammal blubber reference and control materials for use in the determination of halogenated organic compounds and fatty acids

The National Institute of Standards and Technology (NIST) has a diverse collection of control materials derived from marine mammal blubber, fat, and serum. Standard Reference Material (SRM) 1945 Organics in Whale Blubber was recertified for polychlorinated biphenyl (PCB) congeners, organochlorine pesticides, and polybrominated diphenyl ether (PBDE) congeners. SRM 1945 has also been assigned mass fraction values for compounds not frequently determined in marine samples including toxaphene congeners, coplanar PCBs, and methoxylated PBDE congeners which are natural products. NIST also has assigned mass fraction values, as a result of interlaboratory comparison exercises, for PCB congeners, organochlorine pesticides, PBDE congeners, and fatty acids in six homogenate materials produced from marine mammal blubber or serum. The materials are available from NIST upon request; however, the supply is very limited for some of the materials. The materials include those obtained from pilot whale blubber (Homogenates III and IV), Blainville’s beaked whale blubber (Homogenate VII), polar bear fat (Homogenate VI), and California sea lion serum (Marine Mammal Control Material-1 Serum) and blubber (Homogenate V).     

Lipid-soluble and water-soluble arsenic compounds in blubber of ringed seal (Pusa hispida)

High concentrations of arsenic were observed in the blubber of ringed seals (Pusa hispida) in our previous study. To better understand the arsenic accumulation in blubber of marine mammals, arsenicals in the blubber of ringed seal were characterized using high performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICPMS). The most predominant water-soluble arsenical in the blubber was dimethylarsinic acid (DMA), in spite of the predominance of arsenobetaine in other tissues. Lipid-soluble fraction was hydrolyzed under mild (tetraethylammonium hydroxide (TEAH) hydrolysis) and strong (NaOH hydrolysis) conditions, and then an aliquot of hydrolysate was injected onto HPLC–ICPMS. Both TEAH-labile and TEAH-stable/NaOH-labile lipid-soluble fractions contained precursors of DMA. These results suggest that the blubber might be the pool of DMA and DMA-containing precursors in ringed seals.     

Fast and effective sample preparation for determination of organochlorine compounds in fatty tissue of marine mammals using microwave extraction

Summary A rapid and effective method is described for the extraction of organochlorine compounds (PCB 153, PCB 138, PCB 180, p,p-DDE, -HCH, -HCH, -HCH and HCB) from seal blubber and pork fat withn-hexane using a microwave technique. Heating of the non-polarn-hexane was achieved using a microwave transformer. The lipid content of the samples obtained by this extraction was identical to that by Soxhlet extraction. After separation of sample matrix and organochlorines on a silica gel column the organochlorine compounds were determined by GC-ECD. The efficiency of the method was tested with 500 mg spiked fat, extracted using various numbers of extraction cycles. Recoveries of organochlorine compounds in grey seal blubber and spiked pork fat generally exceeded 90 %.     

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.     

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.     

Toxaphene analysis in Great Lakes fish: a comparison of GC-EI/MS/MS and GC-ECNI-MS, individual congener standard and technical mixture for quantification of toxaphene

Toxaphene is considered to be a problematic organochlorine pollutant because of its bioaccumulation potential and persistence in aquatic environments. In this study, whole lake trout and walleye composites were used to evaluate two analytical techniques for total toxaphene and selected congener analysis. The efficacy of using gas chromatography electron ionization tandem mass spectrometry (GC-EI/MS/MS) and electron capture negative ionization mass spectrometry (GC-ECNI-MS) were compared. Although the sensitivity using GC-ECNI-MS was approximately five times greater than GC-EI/MS/MS, the latter provided more consistent inter-Parlar relative response factors (RRF). When using technical calibration mixtures, these results suggest a more accurate total toxaphene measurement was obtained using the GC-EI/MS/MS method. Total toxaphene concentrations in lake trout composites from both methods were highly correlated (R ² = 0.985) with the MS/MS concentrations approximately half of those determined by ECNI, suggesting systematic high bias in toxaphene concentrations when measured using GC-ECNI.     

Attempt to unravel the composition of toxaphene by comprehensive two-dimensional gas chromatography with selective detection

Comprehensive two-dimensional gas chromatography (GC x GC) coupled with micro electron-capture and time-of-flight mass spectrometric (TOF-MS) detection has been used to analyse technical toxaphene. An HP-1 x HT-8 column combination yielded highly structured chromatograms and revealed a complex mixture of over 1000 compounds what is significantly higher number than in any study before. The analysis of a mixture of 23 individual congeners and TOF-MS evaluation of technical toxaphene showed that the chromatogram is structured according to the number of chlorine substituents in a molecule. The nature of the compounds (bornane and camphene) does not appear to have any influence. The sum of the peak areas of all congeners in each group was calculated using laboratory-written software; based on these results, the composition of technical toxaphene as a function of the number of chlorine substituents was provisionally calculated and was found that hepta- and octachlorinated compounds represents 75% of the total toxaphene area.     

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.     

Comparison of Three Techniques for Lipid Removal from Seal Blubber: Gel Permeation,Acid Treatment,and Dialysis with Semipermeable Membrane

Abstract

Harbor seal blubber samples were analyzed for PCDD/Fs and PCBs by splitting the initial extract into three aliquots and applying three different techniques for lipid removal (the first step of sample cleanup methodology for GC-HRMS analysis): gel permeation chromatography (GPC), sulfuric acid treatment, and dialysis through semipermeable membrane. Correlation coefficients of analyte concentrations obtained from three sets of replicate samples ranged from 0.965 to 0.994. In addition, a number of seal blubber samples were processed without pre-extraction using only the dialysis technique. The analyte concentrations in these samples correlated well with the analyte concentrations obtained from dialyzed blubber extracts (correlation higher than 0.998). For all analyses (PCDD/Fs, NO- and MO-PCBs) the average surrogate standard recoveries for the GPC and dialysis techniques varied from 68 to 111%. The recoveries for PCDD/Fs and MO-PCBs standards ranged from 61 to 89% and 36 to 43% for the NO-PCBs when the acid treatment technique was used. Dialysis was proven to be an efficient technique for lipid removal of biological samples in comparison with the GPC and acid treatment techniques.     

Arsenic species in certified reference material MURST-ISS-A2 (Antarctic krill)

Arsenic compounds were quantified in the certified reference material MURST-ISS-A2 (Antarctic krill) using HPLC/ICPMS. The data should prove useful for assessing the accuracy of arsenic speciation procedures.     

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。     

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.     

Gas chromatographic separation of polychlorinated biphenyls on a new apolar capillary column

Eighty one polychlorinated biphenyls (PCBs) and nineteen chlorinated pesticide standards have been analyzed on a newly developed apolar high resolution gas chromatography (HRGC) column. Emphasis was placed on the determination of PCB indicator congeners which are part of national regulations, and of toxic coplanar PCB congeners. The new column enables almost unambiguous quantification of the PCB indicator congeners (PCB 138 can be separated from both PCB 163 and PCB 164; PCB 28 and PCB 31 were also separated and no coelution was observed for PCB 52, PCB 118, and PCB 180). The new column furnished better results than CP-Sil 8 for the analysis of PCB indicator congeners in a sample of seal blubber.     

Determination of HCHs,PCBs, and DDTs in brain tissues of marine mammals off different age

The concentrations of a number of polychlorinated biphenyls and chlorinated pesticides in brain tissues of marine mammals of different age and regional origin were determined by using high-resolution capillary gas chromatography and electron capture detection. Brain tissues of two neonatal and three stillborn northern fur seals (Callorhinus ursinus) collected in the Bering Sea, Pacific Ocean, were examined. In addition, cerebrum, cerebellum, and hypothalamus of one adult female common dolphin (Delphinus delphis) stranded on the coast of Massachusetts, Atlantic Ocean, were examined. It showed clearly that α-HCH was dominant in all brain tissues (90–203 ng/g extractable lipids) compared with other tissues like liver or blubber (45–61 ng/g extractable lipids). This excess of α-HCH in brain tissue was due to only one enantiomer, (+)-α-HCH, whereas in other tissues both enantiomers contributed to the α-HCH concentration. Comparing the overall general xenobiotic burden, the HCH isomers (99–216 ng/g extractable lipids) resemble the PCB (17–105 ng/g extractable lipids) and DDT (111–171 ng/g extractable lipids) levels in brain tissues. The latter two groups exceed the HCHs in liver tissue and in blubber. On a single compound basis, the highest levels are found in brain for α-HCH (fur seal pups: 90–203 ng/g extractable lipids, adult dolphin: 221–305 ng/g extractable lipids), 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153) (fur seal pups: 4–25 ng/g extractable lipids, adult dolphin: 260–377 ng/g extractable lipids) and 4,4′-DDE (fur seal pups: 104–164 ng/g extractable lipids, adult dolphin: 364–625 ng/g extractable lipids). The levels of α-HCH and 4,4′-DDE are comparable. No significant difference concerning the xenobiotic burden between neonatal and stillborn northern fur seals could be seen in contrast to the higher concentrations of the adult common dolphin. The patterns of some xenobiotics in the samples were compared with each other by using statistical methods like the similarity index and the principal component analysis (PCA).     

Spectroscopic characterization of environmentally relevant C10-chloroterpenes from a photochemically modified toxaphene standard

Twenty-five pure environmentally relevant toxaphene components have been isolated from photochemically modified technical toxaphene by means of a combination of column chromatography on silica gel and preparative high resolution liquid chromatography. These compounds are 6 chlorinated camphenes (1–3, 5, 7, and 11) and 19 chlorinated bornanes (4, 6, 8–10, 12–16, 18–24, 26, and 27 according to Table 1). Two further chlorobornanes (17 and 25) have been isolated from a highly chlorinated mixture obtained by the excess chlorination of 2-exo,10-dichlorobornane. The structural elucidation of the isolated compounds has been carried out with spectroscopical methods.