气相色谱法测定多溴联苯的蒸气压

采用气相色谱法,以二氯二苯三氯乙烷(DDT)为参考化合物,测定了6个多溴联苯(PBBs)在不同温度条件下的蒸气压, 然后使用Slide数理统计软件、以最小二乘法回归计算出Antoine方程的A,B,C参数,从而建立了6个PBBs的蒸气压与温度 的关联式。初步探讨了分子连接性指数与蒸气压的相关性,结果发现一阶拓扑指数与蒸气压表现出很好的线性关系,两者 的相关系数的平方大于0.99,标准偏差小于0.08。     

Determination of polybrominated biphenyls in Tasmanian devils (Sarcophilus harrisii) by gas chromatography coupled to electron capture negative ion tandem mass spectrometry or electron ionization high‐resolution mass spectrometry

Two gas chromatography/mass spectrometry (GC/MS) methods for the determination of polybrominated biphenyls (PBBs) by isotope dilution analysis (IDA) using ¹³C₁₂‐PBB 153 in the presence of polybrominated diphenyl ethers (PBDEs) were compared. Recovery of ¹³C₁₂‐PBB 153 which was added to the extracted lipids before sample purification was commenced ranged from 88–117% (mean value 98.2 ± 8.9%). Nevertheless, IDA analysis of PBBs using ¹³C₁₂‐labelled congeners is limited by the potential co‐elution of PBBs with polybrominated diphenyl ethers (PBDEs). The pair PBB 153 and BDE 154 was inspected since M⁺ and [M–2Br]⁺ ions of ¹³C₁₂‐PBB 153 and BDE 154 were only separated by 4 u. Gas chromatography/electron ionization high‐resolution mass spectrometry with selected ion monitoring (GC/EI‐HRMS‐SIM) was suitable when m/z 475.7449 and m/z 477.7429 were used for ¹³C₁₂‐PBB 153 because they are below the monoisotopic peak of the [M–2Br]⁺ fragment ion of hexaBDEs at m/z 479.7. Gas chromatography/electron capture negative ion tandem mass spectrometry selected reaction monitoring (GC/ECNI‐MS/MS‐SRM) measurements could be applied because ¹³C₁₂‐PBB 153 and BDE 154 were separated by GC on a 25‐m Factor Four CP‐Sil 8MS column. Comparative measurements with GC/EI‐HRMS‐SIM and GC/ECNI‐MSMS‐SRM were carried out with samples of Tasmanian devils from Tasmania (Australia), an endangered species due to a virus epidemy which has already proved fatal for half of the population. Both techniques verified concentrations of PBB 153 in the range 0.3–11 ng/g lipids with excellent agreement of the levels in all but two samples. The PBB residue pattern demonstrated that PBB pollution originated from the previous discharge with technical hexabromobiphenyl which is dominated by PBB 153. Other congeners such as PBB 132 and PBB 138 were detected in the Tasmanian devils but the proportions relative to PBB 153 were lower than in the technical product. Samples of healthy and affected Tasmanian devils showed no significant difference in the PBB pollution level. The PBB concentrations in the Tasmanian devils were significantly below those causing toxic effects. On the other hand, PBB concentrations were one level or even higher than PBDEs. Copyright © 2008 John Wiley & Sons, Ltd.     

Chromatographic enrichment and enantiomer separation of axially chiral polybrominated biphenyls in a technical mixture

The separation properties of different chromatographic methods regarding the enantioselective separation of axially chiral (atropisomeric) polybrominated biphenyls (PBB) were studied. For this purpose, the technical hexabromobiphenyl product Firemaster BP-6 was characterised by gas-chromatography coupled to electron capture detection (GC/ECD) and electron-capture negative ion mass spectrometry (GC/ECNI-MS) as well as by liquid chromatographic fractionating on active carbon and celite. Twelve individual PBBs including potential atropisomeric PBBs were isolated from Firemaster BP-6 by reversed-phase high-performance liquid chromatography (HPLC) on three serially coupled octadecylsilane columns. Six of the 12 isolated PBBs (three tri-ortho and di-ortho substituted PBBs, respectively) were separated into atropisomers on a HPLC column containing permethylated beta-cyclodextrin on silica. Moreover, the temperature dependency of the enantiomer separations is discussed. Gas chromatographic enantiomer separation of PBBs is a very demanding task due to high elution temperatures. However, the atropisomers of one tri-ortho substituted PBB congener (PBB 149) could be resolved on a column coated with randomly modified heptakis(6-O-tert.-butyldimethylsilyl-2,3-di-O-methyl)-beta-cyclodextrin in OV 1701.     

Analytical strategies for successful enantioselective separation of atropisomeric polybrominated biphenyls 132 and 149 in environmental samples

Some of the polybrominated biphenyls (PBBs) found in the environment are axially chiral, due to hindered rotation about the interannular phenyl-phenyl bond. This applies for PBB congeners having two or more bromine substituents in ortho-position to this bond. In this study analytical methods were developed that allow determining the enantiomer fraction (EF) of axially chiral (atropisomeric) PBBs in environmental samples. A white-tailed sea eagle egg was used as test sample. The egg extract was purified and further fractionated by normal phase (NP) high performance liquid chromatography (HPLC), yielding enriched fractions of axially chiral PBB 132 and PBB 149. Gas chromatographic (GC) enantioseparation of the atropisomers of PBB 149 was achieved on one of nine tested modified cyclodextrin phases. Due to coelution with an unknown brominated compound, conventional GC/ECNI-MS, which is based on the detection of the bromide ion, did not allow for the establishment of the EF. However, by means of GC/EI-MS-MS it was possible to verify an EF of 0.42-0.43, i.e. a significant enantiomeric enrichment of the second eluting atropisomer of PBB 149 in the white-tailed sea eagle egg. This is the first proof of non-racemic proportions of a chiral PBB in environmental samples. Despite the testing of nine different chiral stationary phases, GC enantioseparation of PBB 132 or other atropisomeric PBB congeners failed. For this reason, an enantioselective reversed-phase HPLC method was developed. This method proved to be a powerful tool for the separation of PBB atropisomers. It was found that even a standard of the di-ortho substituted PBB 153 could be partially separated into atropisomers at 0 degrees C but already enantiomerized at 5 degrees C. For establishing the EF of PBB 132 in the bird egg sample a combination of enantioselective HPLC followed by non-chiral gas chromatography was employed. Using enantioselective HPLC, the atropisomers of PBB 132 were quantitatively targeted into two separate fractions at room temperature (20 degrees C). After addition of internal standards for volume adjustment the relative amounts of the atropisomers in the isolated fractions were quantified by using non-chiral GC/EI-MS analysis. A deviation from the racemic mixture of the atropisomers of PBB 132 in the egg extract could not be statistically proven.     

Predicting gas chromatographic retention times of 209 polybrominated diphenyls (PBBs) for different temperature programs

A method has been developed to predict the retention times of 209 individual polybrominated diphenyl congeners for different temperature programs. The retention equations lnk=A+B/T of five PBBs in gas chromatography (GC) were used to evaluate the properties of the regression coefficients A and B, which are widely accepted as being highly reliable chromatographic retentions. The quantitative relationships between the A and B values of PCBs and those of PBBs were found. The regression equations derived have coefficients of determination greater than 0.999. The A, B values of any PBB can be predicted by using the A, B values of the PCB according to these relationships. Using these predicted A and B values, the retention times of all PBBs can be predicted. This is an important advance in the identification of PBBs because at present there are only a few PBB standards available.     

标准差标准化方法修正的PBBs多效应3D-QSAR模型及其在环境友好性分子修饰中的应用

构建了标准差标准化方法修正的兼具多溴联苯(PBBs)分子红外振动强度、 生物富集性和毒性3种效应的CoMFA模型, 分析了PBBs分子力场对其综合值的影响, 确定取代位点, 并进行兼具易红外光谱检出、 低生物富集性和毒性特征的PBB分子修饰(以PBB-153为例). 研究结果表明, 构建的CoMFA模型对PBBs分子的红外振动强度、 生物富集性和毒性3种效应综合值具有较好的预测和拟合能力, 且具有较好的稳定性, 静电场和立体场的贡献率分别为59.9%和40.1%. 根据模型三维等势图选择正电性高于Br原子的5种取代基团对目标分子PBB-153进行单、 双取代, 筛选出6个3种效应综合值上升的PBB-153衍生物. PBBs衍生物分子单效应计算或预测结果验证表明所构建的兼具PBBs分子红外振动强度、 生物富集性和毒性3种效应综合值的CoMFA模型可以有效应用于PBBs分子的修饰. 设计的PBB-153衍生物分子具有较好的稳定性, 同时阻燃性与目标分子相当, 环境持久性及迁移性方面优于目标分子. 2D-QSAR模型表明, PBBs分子的偶极矩、 最负电荷及邻位Br原子数对其红外振动强度、 生物富集性和毒性单效应和综合值影响趋势一致.     

Fractionation of chlorinated and brominated persistent organic pollutants in several food samples by pyrenyl-silica liquid chromatography prior to GC-MS determination

A high-performance liquid chromatography (HPLC) method using a column of 2-(1-pyrenyl) ethyldimethylsilylated silica was developed in this work in order to achieve satisfactory and reproducible fractionation of polychlorinated biphenyls (PCBs) from brominated flame retardants (BFRs) (polybrominated diphenylethers, PBDEs; and polybrominated biphenyls, PBBs). After the study of different chromatographic parameters (mobile phase composition and separation temperature were the most important) an isocratic elution with isooctane:toluene (98:2, v/v) at a flow-rate of 1 mL/min, a temperature of 45 °C, and UV-detection at 225 nm was selected for fractionation of PCBs (time region, 4.0-5.8 min) from PBDEs (5.8-9.0 min) and from PBBs (5.8-11.0 min). The applicability of this method to food samples was demonstrated by fractionating PCBs from PBDEs in three food samples (cheese, milk, and fish). Interferences from PCBs (present in real samples at much higher concentrations than PBDEs) were removed in this way. In addition, by analysing these samples by gas chromatography-mass spectrometry (GC-MS) with and without previous fractionation we were able to observe an improvement in detection sensitivity for PBDEs after HPLC fractionation.     

Optimization and Simultaneous Determination of Alkyl Phenol Ethoxylates and Brominated Flame Retardants in Water after SPE and Heptafluorobutyric Anhydride Derivatization followed by GC/MS

A gas chromatography–mass spectrometry (GC–MS) method was investigated for the simultaneous analysis of two types of endocrine disrupting compounds (EDCs), i.e., alkylphenol ethoxylates and brominated flame retardants (BFRs), by extraction and derivatization followed by GC–MS. Different solid phase extraction (SPE) cartridges (Cleanert PestiCarb, C₁₈, Cleanert-SAX and Florosil), solvents (toluene, tetrahydrofuran, acetone, acetonitrile and ethyl acetate) and bases (NaHCO₃, triethylamine and pyridine) were tested and the best chromatographic analysis was achieved by extraction with Strata-X (33?μm, Reverse Phase) cartridge and derivatization with heptafluorobutyric anhydride at 55?°C under Na₂CO₃ base in hexane. It was observed that APE together with lower substituted PBBs (PBB1, PBB10, PBB18 and PBB49), HBCD and TBBPA can be determined simultaneously under the same GC conditions. This simple and reliable analytical method was applied to determining trace amounts of these compounds from wastewater treatment plant samples. The recoveries of the target compounds from simulated water were above 60?%. The limit of detection ranged from 0.01 to 0.15?μg L^?1 and the limit of quantification ranged from 0.05 to 0.66?μg L^?1. There were no appreciable differences between filtered and unfiltered wastewater samples from Leeuwkil treatment plant although concentration of target analytes in filtered influent was slightly lower than the concentration of target analytes in unfiltered influent water. The concentrations of the target compounds from the wastewater treatment were determined from LOQ upwards.     

Theoretical Study on the Photodegradation Mechanism of Nona‐BDEs in Methanol

Polybrominated diphenyl ethers (PBDEs) have received special environmental concern due to their potential toxicity to humans and wildlife worldwide, however, it is difficult to reveal their dominant photochemical degradation pathways by experiment. We explored the reaction mechanisms of photochemical degradation–debromination of three nona‐BDEs in methanol using theoretical calculations, in which time‐dependent density functional theory (TDDFT) combined with the polarizable continuum (PCM) model is applied. The selectivity of debromination was studied, and the major octa‐BDE products photochemically debrominated from nona‐BDEs were identified. We find that the debromination reaction results from the electronic transitions from π to σ* orbitals when nona‐BDEs are exposed to UV‐light in the sunlight region, at which point the two low‐lying excited states for each nona‐BDE are πσ*(5Br) and πσ*(4Br), which correlate to the σ* orbitals located on the penta‐Br and tetra‐Br substituted phenyls, respectively. Our calculations indicate that each nona‐BDE may degrade to form three kinds of octa‐BDE products via the πσ*(5Br) state, whereas only one kind of octa‐BDEs can be formed via the πσ*(4Br) state. Our calculations can interpret the recent experiments successfully.     

Optimization and Simultaneous Determination of Alkyl Phenol Ethoxylates and Brominated Flame Retardants in Water after SPE and Heptafluorobutyric Anhydride Derivatization followed by GC/MS

A gas chromatography–mass spectrometry (GC–MS) method was investigated for the simultaneous analysis of two types of endocrine disrupting compounds (EDCs), i.e., alkylphenol ethoxylates and brominated flame retardants (BFRs), by extraction and derivatization followed by GC–MS. Different solid phase extraction (SPE) cartridges (Cleanert PestiCarb, C₁₈, Cleanert-SAX and Florosil), solvents (toluene, tetrahydrofuran, acetone, acetonitrile and ethyl acetate) and bases (NaHCO₃, triethylamine and pyridine) were tested and the best chromatographic analysis was achieved by extraction with Strata-X (33 μm, Reverse Phase) cartridge and derivatization with heptafluorobutyric anhydride at 55 °C under Na₂CO₃ base in hexane. It was observed that APE together with lower substituted PBBs (PBB1, PBB10, PBB18 and PBB49), HBCD and TBBPA can be determined simultaneously under the same GC conditions. This simple and reliable analytical method was applied to determining trace amounts of these compounds from wastewater treatment plant samples. The recoveries of the target compounds from simulated water were above 60 %. The limit of detection ranged from 0.01 to 0.15 μg L⁻¹ and the limit of quantification ranged from 0.05 to 0.66 μg L⁻¹. There were no appreciable differences between filtered and unfiltered wastewater samples from Leeuwkil treatment plant although concentration of target analytes in filtered influent was slightly lower than the concentration of target analytes in unfiltered influent water. The concentrations of the target compounds from the wastewater treatment were determined from LOQ upwards.

     

气相色谱质谱法分析土壤中多溴联苯和多溴联苯醚类化合物

建立了气相色谱-质谱法(GC-MS)分析土壤中的18种多溴联苯(PBBs)和多溴联苯醚类(PBDEs)化合物的方法.利用快速溶剂萃取(ASE)技术和凝胶净化系统(GPC)进行土壤样品的前处理,(13)C标记物作为进样内标和替代标,采用电子轰击源气相色谱质谱法(GC-EI/MS )分析-溴至七溴代PBBs和PBDEs,负...     

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.     

Supercritical fluid extraction of polyhalogenated pollutants from aquaculture and marine environmental samples: a review

This article focuses on the state-of-the-art in sample preparation using supercritical fluid extraction (SFE), to monitor the content of polyhalogenated pollutants in aquaculture and marine environmental samples. Marine sediments and biological applications, including several types of samples matrices (fish, shellfish, seaweed and fish feed) and analyte groups (polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), polybrominated diphenylethers (PBDEs), polychlorinated dibenzo-p-dioxin (PCDD)/Fs and organochlorinated pesticide (OCPs)) are discussed with respect to SFE use and optimisation of conditions. We also discuss the great analytical potential of SFE, the integration of the extraction and clean-up steps for rapid sample processing justifying its use for routine work. The most recent SFE applications to the determination of these pollutants in marine environmental (biota and sediment) samples, published in the last 15 years, are reviewed.     

Versatile and fast gas chromatographic determination of frequently used brominated flame retardants in styrenic polymers

Two versatile and fast methods to identify and quantify brominated flame retardants (BrFRs) in styrenic polymers were developed. Gas chromatography/mass spectrometry (GC/MS) as well as gas chromatography with electron-capture detection (GC/ECD), both following ultrasonic-supported dissolution and precipitation (USDP), were applied. The substance range includes poly-brominated biphenyls (PBBs) and diphenyl ethers (PBDEs), as well as other commonly used flame retardants (FRs), including two phosphate-based flame retardants. The methods were verified using congener standards and flame-retardant polymer samples. Good recoveries were found. Overall run time for the analysis, including sample preparation, is less than 60min.     

Heterolytic activation of hydrogen using frustrated Lewis pairs containing tris(2,2',2'-perfluorobiphenyl)borane

The extremely sterically hindered borane tris(2,2',2'-perfluorobiphenyl)borane (PBB) has been structurally characterised. In combination with bulky nitrogen bases, it forms the 'frustrated Lewis pairs' (FLPs) PBB/2,2,6,6-tetramethylpiperidine (TMP) (1), PBB/1,4-diazobicyclo[2.2.2]-octane (DABCO) (2) and PBB/2,6-lutidine (lut) (3). These novel, unquenched acid-base pairs have been shown to effect facile room temperature heterolytic cleavage of dihydrogen to form the ammonium borate salts [2,2,6,6-Me(4)C(5)H(6)NH(2)][HB(C(12)F(9))(3)] (4) and [N(C(2)H(4))(3)NH][HB(C(12)F(9))(3)] (5), and lutidinium borate [2,6-Me(2)C(5)H(3)NH][HB(C(12)F(9))(3)] (6). Although these reactions are equilibria, the reverse reaction and release of hydrogen gas was not apparent at temperatures up to 120 °C. The relative Lewis acidity of PBB has been determined using the Gutmann-Beckett method.     

Solvent removal/thermal desorption (SRTD) for extract concentration and capillary column injection

Many solvent extracts must be concentrated prior to analysis. Both Kuderna-Danish (K-D) concentration and inert gas blowdown are commonly used. Significant losses often occur with the latter. Solvent removal/thermal desorption (SRTD) on a precolumn was investigated here as an alternative or supplement to these methods. The compounds studied included polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs). SRTD was carried out by injecting 100 μL of extract into a cartridge-type precolumn, selectively volatilizing the solvent with a stream of carrier gas, then thermally desorbing the analytes to a fused silica capillary gas chromatography (GC) column. The mean total recoveries and mean standard errors obtained were 109 and ±12%, respectively. SRTD was found to give sharper peaks than were obtainable with on-column injection. Method detection limits accessible for PCBs by capillary GC with electron impact mass spectrometry with the assistance of SRTD were estimated. Overall, SRTD was found to be an effective, rapid, high recovery concentration method for solvent extracts.     

HPLC isolation and NMR structure elucidation of the most prominent octabromo isomer in technical octabromo diphenyl ether

The major octabromo isomer of technical octabromo diphenyl ether mixture (technical octaBDE) DE-79 was isolated by RP-HPLC. Three serially coupled columns (each 250 mm long) enabled a good separation of the target compound from other congeners using 100% ACN as eluent. Approximately 100 microg of the target compound was isolated with a purity of >90% and investigated by MS for confirmation of the degree of bromination. 1H-NMR and 2-D 1H-13C correlation NMR spectra unequivocally clarified that the octaBDE in question is 2,2',3,3',4,4',6,6'-octabromodiphenyl ether (BDE 197). Based on annual production rates of technical BDE products (1999/2001), approximately 380 tons of BDE 197 were annually produced which, on the long term, may enter the environment. Compared with other individual BDE congeners, BDE 197 has the seventh highest application rate. Reductive debromination of BDE 197 can lead to four hepta-, 15 hexa-, 23 penta-, and 28 tetra-BDE isomers, respectively. This variety includes all known major BDEs of environmental concern (BDE 47, 85, 99, 100, 153, 154, and 183). The identification of BDE 197 in technical octaBDE DE-79 strongly suggests that research on the environmental fate of BDEs should include this key-BDE congener.     

Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the identification of organobrominated compounds in bluefin tuna

This study evaluates comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (GC×GC-ToF MS) for the simultaneous analysis of several classes of organobromines (OBs), including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), methoxylated PBDEs (MeO-PBDEs), several halogenated naturally produced compounds (HNPs) and eight novel brominated flame retardants (NBFRs), polybrominated hexahydroxanthene derivates (PBHDs), 2,4,6-tribromoanisole and a mixed halogenated compound (MHC-1), in bluefin tuna muscles. The proposed methodology maximised separation of both within and among OB families, and among these and other halogenated micropollutants detected in these samples and co-extracted matrix components. Special attention has been paid to solve co-elution problems observed during the analysis of OBs with one-dimensional GC-based techniques. Satisfactory separation among several relevant PBDEs and MeO-PBDEs has been obtained allowing their unambiguous determination in a single run. Additional studies were conducted to identify selected NBFRs and HNPs. 2,4-Dibromoanisole, a dibromophenol isomer and hexabromobenzene were identified in the investigated samples. Several new tri- and tetra-BHD derivates were also identified, indicating that these compounds could apparently exist as structured families in nature. In addition, a tetrabrominated diMeO-biphenyl and two tetrabrominated diMeO-BDEs were also tentatively identified.     

气相CBr2的激光诱导荧光光谱

本文报道了在交叉分子束装置中氟原子和二溴甲烷反应生成的CBr2的气相激光诱导荧光光谱的首次实验结果。位于585-664nm范围内的激光诱导荧光光谱由22个峰组成,被指定为CBr2的A(V1'V2'0)←X(000)(V1'=0,1; V2'=0-12)跃迁。从光谱导出v00=14885cm^-^1, 上态振动光谱常数v1'=460, v2'=189cm^-^1, x12'=3.10,x22'=-0.27cm^-^1。本实验结果与CBr2的低温固相光谱进行比较, 发现固相光谱较气相光谱明显蓝移, 确认了CBr2是F+CH2Br2过程的两步反应的产物。