An organically modified silicate molecularly imprinted solid-phase microextraction device for the determination of polybrominated diphenyl ethers

An organically modified silicate (ORMOSIL) SPME stationary phase molecularly imprinted with BDE-209 has been successfully fabricated by conventional sol-gel technique from phenyltrimethoxysilane and tetraethoxysilane. The thickness of the ORMOSIL-SPME stationary phase, on fused-silica optical fibres, was measured to be ca. 9.5 μm with a volume of ca. 0.12 μL. Rebinding assays and Scatchard analysis revealed that the imprinted ORMOSIL-SPME stationary phase possessed a binding affinity, K_B, of 7.3 ± 1.7 × 10¹⁰ M⁻¹ for BDE-209, with a receptor site density, B_max, of 1.2 × 10⁻³ pmol per SPME device. Besides its molecular template, the ORMOSIL-SPME stationary phase also showed good affinity (log K_B ≥ 9.5) for smaller BDE congeners commonly found in the natural environment. The density of receptor sites within the imprinted matrix for those smaller BDE congeners was even higher than that for BDE-209. This may be attributable to the binding site heterogeneity of the imprinting process that creates deformed binding sites that are suitable for the accommodation of the smaller BDE congeners. Compared to the commercially available polyacrylate and polydimethylsiloxane SPME stationary phases, the imprinted ORMOSIL-SPME devices showed much higher pre-concentration ability towards polybrominated diphenyl ethers (PBDEs), even in direct immersion sampling at room temperature. Coupled with GC-NCI-MS and GC-μECD, the imprinted ORMOSIL-SPME device was able to achieve detection sensitivity of 0.2-3.6 pg mL⁻¹ and 1-8.8 pg mL⁻¹, respectively, for commonly occurring BDE congeners, including medium to high molecular weight PBDEs. The imprinted ORMOSIL-SPME device has been successfully applied to monitor PBDE contents in municipal wastewaters.     

Optimisation of the analytical method for octa-, nona- and deca-brominated diphenyl ethers using gas chromatography–quadrupole mass spectrometry and isotope dilution

An analytical method for higher brominated congeners of polybrominated diphenyl ethers (PBDEs) was optimised using a gas chromatograph equipped with an electron impact ionisation-quadrupole mass spectrometer (GC-EI-qMS) and five native PBDEs and three ¹³C₁₂-labelled congeners in biological and environmental samples (mussels, sediment, dust). In the optimised instrumental conditions, abundance and repeatability improved with increase in temperature of the ion source. The instrumental detection limits (IDLs) for BDE-196, BDE-197, BDE-206, BDE-207 and BDE-209 were 0.1, 0.1, 0.2, 0.3 and 0.6?pg, respectively. When compared to the previous reports, the IDLs were the same as for electron capture negative ionisation (ECNI) or EI-double focusing magnetic sector (EI-Sector) mass spectrometer, indicating that sensitive determination could be achieved using a conventional GC-EI-qMS. Validation of the method was carried out by the analysis of reference materials and mussel samples. We confirmed that the concentrations quantified using this method was in the range of reported values for reference materials. Similar concentrations were found in mussels, which were analysed previously by our group. Thus, we conclude that a conventional GC-EI-qMS can be applied for analysis of higher brominated PBDEs in various environmental and biota matrices.     

Rapid and simultaneous determination of polychlorinated biphenyls and their main metabolites (hydroxylated and methyl sulfonyl) by gas chromatography coupled to mass spectrometry: Comparison of different ionisation modes

Instrumental methods based on gas chromatography coupled to mass spectrometry (GC–MS) have been developed and compared using two different MS ionisation modes, electron impact (EI) and electron capture negative ionisation (ECNI), for the fast, quantitative and simultaneous determination of polychlorinated biphenyls (PCBs) and their main metabolites (hydroxylated PCBs, OH-PCBs, and methyl sulfone PCBs, MeSO₂-PCBs). Parameters affecting chromatographic separation and MS detection were evaluated in order to achieve the highest selectivity and sensitivity for both operation modes. The analytical characteristics of the developed methods were studied and compared in terms of linear range, limits of detection (LODs), limits of quantification (LOQs), and instrumental precision (repeatability and intermediate precision). Both ionisation methods showed similar precision, being relative standard deviations (RSD, %) lower than 9% and 14% for repeatability and intermediate precision, respectively. However, better LODs (from 0.01 to 0.14 pg injected for the three families of congeners studied) were achieved using ECNI-MS as ionisation mode. The suitability of the developed method was demonstrated through their application to fish liver oil samples.     

Determination of polybrominated diphenyl ethers in fish tissues by matrix solid-phase dispersion and gas chromatography coupled to triple quadrupole mass spectrometry: Case study on European eel (Anguilla anguilla) from Mediterranean coastal lagoons

This paper describes the development and validation of an analytical methodology to determine 28 polybrominated diphenyl ethers (PBDEs) in European eel (Anguilla anguilla) tissues using matrix solid-phase dispersion (MSPD) and gas chromatography coupled to triple quadrupole mass spectrometry (GC-QQQ-MS/MS). A total of 28 PBDEs were targeted, including tri- to deca-brominated congeners.The robustness and effectiveness of the proposed sample preparation procedure was demonstrated in lipid-rich eel tissues. The use of batch MSPD with activated silica gel and H₂SO₄-impregnated silica gel, followed by H₂SO₄ digestion and multilayer cartridge clean-up allowed for complete lipid removal and eliminated matrix effects during GC-QQQ-MS/MS analysis. The average PBDE recoveries from eel muscle samples spiked with PBDEs at two levels were in the range 56.2-119.0%. Precision was satisfactory since relative standard deviations were lower than 19.6%, regardless of spike level, and method quantification limits ranged between 1 and 170 pg g⁻¹ (wet weight).The method demonstrated its successful application for the analysis of eel samples from two coastal lagoons located on the western French Mediterranean coast. All samples tested positive, but for tri- to hexa-brominated congeners only and total PBDE levels observed in this study were in the range 0.08-1.80 ng g⁻¹ wet weight.     

Development of an analytical procedure for the determination of polybrominated diphenyl ethers in environmental water samples by GC–ICP-MS

Polybrominated diphenyl ethers (PBDEs) are flame retardants, which due to their widespread use are frequently present as pollutants in the environment. In the EU Water Framework Directive (WFD) six PBDE congeners (BDE 28, BDE47, BDE 99, BDE 100, BDE 153 and BDE 154) are listed as priority substances. The uncertainty of the analytical method used for their determination in water samples at environmental quality standard (EQS) level (0.5 ng L⁻¹ for the ΣPBDEs) should be equal or less than 50% and the limit of quantification (LOQ) for ΣPBDEs below 0.15 ng L⁻¹. To meet these requirements, an analytical procedure for the determination of these six PBDEs in environmental water samples by gas chromatography–inductively coupled plasma mass spectrometry (GC–ICP-MS) was developed. The acidification of water samples to pH 2 maintained the stability of PBDEs for at least 20 days. The use of Tris–citrate buffer enabled efficient desorption of PBDEs from suspended particulate matter (SPM) and humic acids (HA), and their further quantitative solvent extraction into 2 mL of iso-octane. When 300 mL of water sample was used for analysis and the organic phase concentrated to 25 μL, the expanded uncertainty for determination of PBDEs at EQS level was found to be around 40% (a coverage factor for a confidence level of 95%, k = 2), and the LOQ for the ΣPBDEs 0.109 ng L⁻¹. Finally, to demonstrate the applicability of the newly developed GC–ICP-MS procedure, PBDEs were determined in river and sea water samples.     

Determination of 41 polybrominated diphenyl ethers in soil using a pressurised solvent extraction and GC-NCI-MS method

A rapid and reliable analytical method based on pressurised solvent extraction (PSE) and GC-NCI-MS was developed for the determination of 41 different PBDEs in soil. All PBDEs, including mono- to hepta-BDEs (sum of 39 congeners), one nona-BDE and deca-BDE, were efficiently extracted from soil samples using the extraction technology of PSE. The extract was then cleaned up on a florisil column. Satisfactory separation of 41 PBDE congeners was obtained on a 15-m DB-5MS capillary column, saving the use of another 30-m column specific for the separation of mono- to hepta-BDEs. PBDEs were identified and quantified by GC-MS in negative chemical ionisation (NCI) mode, and further confirmed in semi electron impact (SEI) mode when the ion source was also NCI. The method detection limits ranged from 0.01 to 0.03?ng?g^?1?dw for mono- to hepta-BDEs, 1.43?ng?g^?1?dw for the nona-BDE and 0.20?ng?g^?1?dw for deca-BDE. The applicability of the method was tested in soil samples collected from an e-waste recycling site at Guiyu. Twenty-one PBDEs (mono- to deca-) were detected, and eighteen congeners were quantified. The concentration range of PBDEs was 0.78–436?ng?g^?1?dw. BDE-47, BDE-99, BDE-153, BDE-183, BDE-206 and BDE-209 were the dominant congeners, and BDE-209 accounted for 62% of the total PBDEs. The congener profiles of PBDEs in soil samples were similar to those in three commercial PBDE products (Penta-, Octa- and Deca-BDE), and Deca-BDE product was the most important contributor.     

Dispersive liquid-liquid microextraction followed by reversed phase-high performance liquid chromatography for the determination of polybrominated diphenyl ethers at trace levels in landfill leachate and environmental water samples

A simple, rapid and efficient method, dispersive liquid-liquid microextraction (DLLME), has been developed for the extraction and preconcentration of polybrominated diphenyl ethers (PBDEs) in water samples. The factors influencing microextraction efficiencies, such as the kind and volume of extraction and dispersive solvent, the extraction time and the salt effect, were optimized. Under the optimum conditions (sample volume: 5 mL; extraction solvent: tetrachloroethane, 20.0 μL; dispersive solvent: acetonitrile, 1.00 mL; extraction time: below 5 s and without salt addition), the enrichment factors and extraction recoveries were high and ranged from 268 to 305 and 87.0 to 119.1%, respectively. Linearity was observed in the range 0.05-50 ng mL⁻¹ for BDE-28 and BDE-99, and 0.1-100 ng mL⁻¹ for BDE-47 and BDE-209, respectively. Coefficients of correlation (r²) ranged from 0.9995 to 0.9999. The repeatability study was carried out by extracting the spiked water samples at concentration levels of 50 ng mL⁻¹ for BDE-28 and BDE-99, and 100 ng mL⁻¹ for BDE-47 and BDE-209, respectively. The relative standard deviations (R.S.D.s) varied between 3.8 and 6.3% (n = 5). The limits of detection (LODs), based on signal-to-noise ratio (S/N) of 3, ranged from 12.4 to 55.6 pg mL⁻¹ (the wavelength of detector at 226 nm). The relative recoveries of PBDEs from tap, lake water and landfill leachate samples at spiking levels of 5, 10 and 50 ng mL⁻¹ were in the range of 89.7-107.6%, 114.3-119.1% and 87.0-90.9%, respectively. As a result, this method can be successfully applied for the determination of PBDEs in landfill leachate and environmental water samples.     

Optimized determination of polybrominated diphenyl ethers and polychlorinated biphenyls in sheep serum by solid-phase extraction-gas chromatography-mass spectrometry

We describe a solid-phase extraction (SPE) method, followed by gas chromatography-mass spectrometry (GC-MS), for the simultaneous determination of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in sheep serum samples. The denaturation of serum proteins by formic acid, water-1-propanol and water-2-propanol were compared and optimized. Seven different solid-phase sorbents were tested and it was found that Strata-X cartridge (200 mg, 6 mL) gave the best recoveries (92-106%, SD < 6%, n = 3) for all the target analytes. The different extraction solvents (iso-hexane and dichloromethane), either alone or in combination, were used to extract these persistent organic compounds from spiked serum samples by SPE. Removal of co-extracted biogenic materials was achieved using adsorption chromatography with acid modified silica and activated silica. Iso-hexane was found to be the most appropriate solvent for clean-up providing good recoveries and clear chromatographic separation; its use is preferable to that of DCM because it is less environmentally toxic. The limits of detection (LOD) of the proposed method were 47-105 pg g⁻¹ and 16-24 pg g⁻¹ for the different PBDEs and PCBs studied, respectively. The developed method was linear over the range from 0.05 to 30 ng g⁻¹, for all PBDEs except PBDE 183 (0.10-30 ng g⁻¹), and from 0.02 to 30 ng g⁻¹ for all tested PCB congeners. The established method was successfully applied to sheep serum samples from Scotland, UK, for the determination of the target PBDEs and PCBs.     

Determination of the rate of production and dissolution of biosilica in marine waters by thermal ionisation mass spectrometry

A new method is described for a precise and simultaneous determination of the rate of production and dissolution of biosilica in marine waters, using isotopic dilution technique. No HF or F₂ is required for chemical preparations as the change in isotopic composition is measured on silica producing SiO₂⁻ ions. The seawater sample flask is spiked with ³⁰Si(OH)₄ (<10% of increase in situ concentration) and incubated in in situ conditions. At the end of incubation, changes of the ³⁰Si:²⁸Si ratios in particulate and liquid phases are measured by using a thermal ionisation mass spectrometer Finnigan THQ. The relative analytical precision of the isotopic ratio measurements is <0.5%. The limit of detection of the change in isotopic ratio during incubation is 0.02 atom%. The overall repeatability determined on eight subsamples (average production: 0.23 μM day⁻¹; average dissolution: 0.07 μM day⁻¹) is ±0.02 and ±0.01 μM day⁻¹ for production and dissolution, respectively. Using mass and isotopic balances of the particulate and dissolved phases in the incubation flask, the best estimates for production and dissolution rates are calculated iteratively. This method was applied to 112 samples of marine waters (production, range: 0.00-2.38 μM day⁻¹; dissolution, range: 0.00-1.18 μM day⁻¹).     

New perspective on the determination of flame retardants in sewage sludge by using ultrahigh pressure liquid chromatography–tandem mass spectrometry with different ion sources

Analysis of 11 polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A bis 2,3-dibromopropylether (TBBPA-bis), tetrachlorobisphenol A (TCBPA), tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs) was optimized by ultrahigh pressure liquid chromatography/tandem mass spectrometry (UPLC–MS/MS) operating in negative ion (NI) mode. Electrospray ionization (ESI), atmospheric pressure photoionization (APPI) and atmospheric pressure chemical ionization (APCI) sources were tested and for PBDEs APCI gave higher sensitivity than APPI while for TBBPA-bis APCI and APPI showed similar performance. ESI was the best option for TCBPA, TBBPA and HBCDs. Detection limits were between 20 and 59 fg for the compounds analyzed by ESI, 0.10 and 0.72 pg for PBDEs and 6 pg for TBBPA-bis. The matrix effect of sewage sludge extract was also tested showing negligible ion suppression for APCI and an increase of the background level of all investigated pollutants leading to a worsening of the limits of quantification by a factor between 1.2 and 3.3. The UPLC-APCI/MS/MS method for PBDEs, after pressurized liquid extraction (PLE), was validated by comparison with the concentration values from the NIST 1944 standard reference material. The advantages of the methods include low detection limits, PBDE congeners specificity using selected multiple reaction monitoring (MRM) transitions, and the absence of thermal degradation of higher PBDE congeners, especially BDE-209. The methods were applied for the determination of the above reported flame retardants in sewage sludge in order to get more information about the degradation on PBDEs (in particular BDE-209) during municipal wastewater treatments.     

Determination of polybrominated diphenyl ethers in water and soil samples by cloud point extraction-ultrasound-assisted back-extraction-gas chromatography–mass spectrometry

A novel and efficient analytical methodology is proposed for extracting and preconcentrating polybrominated diphenyl ethers (PBDEs) from samples of environmental interest prior gas chromatography–mass spectrometry (GC–MS) analysis. It is based on the induction of micellar organized medium by using a non-ionic surfactant (Triton X-114) to extract the target PBDEs. To enable coupling the efficient extracting technique with GC analysis, ultrasound-assisted back-extraction (UABE) into an organic solvent was required. Several factors, including surfactant type and concentration, equilibration temperature and time, ionic strength, pH and buffers nature and concentration were studied and optimized over the extraction efficiency of the proposed technique. Under optimal experimental conditions, the target analytes were quantitatively extracted achieving an enrichment factor of 250 when 10 mL aliquot of ultrapure water spiked with PBDE-standard mixture (10 pg mL⁻¹ each PBDE) was extracted. Method detection limits (MDLs) calculated with aqueous PBDEs solutions as three times the signal-to-noise ratio (S/N), ranged from 1 to 2 pg mL⁻¹ with RSDs values ≤8.5% (n = 5). The coefficients of estimation of the calibration curves obtained following the proposed methodology were ≥0.9987 and linear range of all PBDEs was 4–150 pg mL⁻¹. The proposed methodology was validated by carrying out a recovery study by spiking the samples at two different concentration levels of PBDEs (10 and 50 pg mL⁻¹ for waters samples). Recoveries values in the range of 96–106% for water samples were obtained showing satisfactory robustness of the method for analyzing PBDEs in water samples. The proposed methodology was applied for the analysis of PBDEs: 2,2′,4,4′-tetraBDE (BDE-47), 2,2′,4,4,5-pentaBDE (BDE-99), 2,2′,4,4,6-pentaBDE (BDE-100) and 2,2,4,4′,5,5′-hexaBDE (BDE-153) in water samples, including drinking, lake, river water and soil samples. Significant quantities of PBDEs were not found in the analyzed samples.     

Preconcentration and determination of polybrominated diphenyl ethers in environmental water samples by solid-phase microextraction with Fe3O4-coated bamboo charcoal fibers prior to gas chromatography–mass spectrometry

In this paper, bamboo charcoals were modified using Fe₃O₄ nanosheets for the first time. The composites, as a novel solid-phase microextraction (SPME) fiber coating, were used for the extraction of seven polybrominated diphenyl ethers (PBDEs) in environmental water samples. The extraction factors (stirring rate, extraction time, and ionic strength) and desorption factors (desorption time and desorption temperature) of the fibers were systematically investigated and optimized. Under optimum conditions, the linear range was 1–1000 ng L⁻¹. Based on the ratio of chromatographic signal to base line noise (S N⁻¹ = 3), the limits of detection (LODs) can reach 0.25–0.62 ng L⁻¹. The novel method was successful in the analysis of PBDEs in real environmental water samples. The results indicate that bamboo charcoal/Fe₃O₄ as an SPME coating material coupled with gas chromatography–negative chemical ionization-mass spectrometry is an excellent method for the routine analysis of PBDEs at trace levels in environmental water samples.     

Preparation for nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting and its application to determine trace copper by room temperature phosphorimetry

Nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting (NCM-PVA-I-I) was prepared using Cu²⁺ as template. The cavity in NCM-PVA-I-I matched Cu²⁺ very well and the selectivity was high. Cu²⁺ entered the cavity and then could form ionic association ([Cu²⁺]·[(Fin⁻)₂]) with the anion of fluorescein (Fin⁻) outside the cavity by electrostatic effect. [Cu²⁺]·[(Fin⁻)₂] could emit strong and stable room temperature phosphorescence on NCM-PVA-I-I. Its ΔI_p was proportional to the content of Cu²⁺. Based on the above facts, a new method for the determination of trace copper by solid substrate-room temperature phosphorimetry (NCM-PVA-I-I-SS-RTP, SS-RTP is the abbreviation of solid substrate-room temperature phosphorimetry) using NCM-PVA-I-I technique has been established. The linear range of this method was 2.00-144.00 fg Cu²⁺ spot⁻¹ (sample volume: 0.40 μL spot⁻¹, corresponding concentration: 5.00-360.00 pg mL⁻¹), and the detection limit calculated by 3Sb/k was 0.43 fg Cu²⁺ spot⁻¹ (corresponding concentration: 1.1 × 10⁻¹² g mL⁻¹, n = 11). Samples containing 2.00 and 144.00 fg Cu²⁺spot⁻¹ were measured, respectively, for seven times and R.S.D.s were 3.5% and 4.7%. NCM-PVA-I-I-SS-RTP could combine very well the characteristics of both the high sensitivity of SS-RTP and the high match and selectivity of NCM-PVA-I-I, and it was rapid, accurate, sensitive and with good repeatability. It has been successfully applied to determine trace copper in human hair and tea samples.     

Simple spectrophotometric assessment of the trans-/cis-resveratrol ratio in aqueous solutions

The solubility and molar absorptivity of trans- and cis-resveratrol isomers in aqueous solvents are poorly described. This study aimed to develop and describe a new simple method for the determination of trans- and cis-resveratrol concentrations in aqueous solutions. Up to 300 μM trans-resveratrol was dissolved in water by sonication for 2 h. Cis-resveratrol was obtained by exposing a 100-μM trans-resveratrol aqueous solution to sunlight for 8 h, followed by HPLC separation and analysis by mass spectrometry (resveratrol oxidation products were absent). Accurate values for UV absorbance in water were ελmax=ε304 nm=30 335 M−1 cm−1, ?_286 nm = 23 400 M⁻¹ cm⁻¹ for trans-resveratrol and ελmax=ε286 nm=14 986 M−1 cm−1, ?_304 nm = 9515 M⁻¹ cm⁻¹ for cis-resveratrol. These values allowed us to propose formulae to assess the trans-/cis-resveratrol ratio in water, using a simple and reliable UV-vis spectrophotometric method. Statistical analysis revealed no significant difference between our UV method and the commonly used HPLC method. All these data are transferable to 150 mM NaCl and 10 mM phosphate buffer solutions, which could be particularly useful for cell culture, ex vivo and in vivo studies.     

Improved GC/ECNI-MS sensitivity of decabromodiphenyl ether determination on 30 m columns by increasing the carrier gas flow after a modified gel permeation chromatographic cleanup protocol employing cyclohexane/ethyl acetate as eluent

BDE-209 is the predominant constituent of the commercial mixture decabromodiphenyl ether which is used as brominated flame retardant (BFR). Owing to difficulties associated with the high mass (thermal instability and low vapour pressure), short GC columns (≤15?m) have been suggested for its analysis while longer columns (30–50?m) are suggested for other polybrominated diphenyl ether (PBDE) congeners. To overcome this considerable expenditure in the analysis of PBDEs, we aimed at increasing the sensitivity of BDE-209 analysis by gas chromatography coupled with electron-capture negative ion mass spectrometry (GC/ECNI-MS) on a 30?m column. The chromatographic performance of BDE-209 on the 30?m GC column was improved by increasing the carrier gas flow from initially 1.2?mL?min^?1 to 5 or 10?mL?min^?1 after the last octabromo diphenyl ether (Br₈DE) congener was eluted. With this high carrier gas flow, the column residence time of BDE-209 was shortened by ～25%, the peak height was increased and, consequently, the limit of detection by GC/ECNI-MS in selected ion monitoring (SIM) mode was improved. When this high-flow GC/ECNI-MS-SIM method was applied to a sediment sample, we realized that gel permeation chromatography (GPC) – used for the removal of lipids and/or sulphur – provided low recovery rates for BDE-209. The large molecule BDE-209 eluted late and only 50% was recovered by our previous standard protocol for polyhalogenated compounds. Application of a modified GPC procedure with a longer collection time increased the recovery of BDE-209 in the GPC step to ～90%.     

Determination of trace mercury by solid substrate-room temperature phosphorimetry based on catalytic effect of Hg(2+) on formation of the ion association complex [Fe(bipy)(3)](2+)[(FinBr(4))(2)](2-)

A new solid substrate-room temperature phosphorimetry method for the determination of trace mercury has been established. It bases on the fact that in acetic acid medium, Hg²⁺ ion can catalyze the substitute reaction of CN⁻ ligand in [Fe(CN)₆]⁴⁻ by 2,2′-bipyridyl (bipy), and the resultant [Fe(bipy)₃]²⁺ cation can react with FinBr₄⁻ anion of tetrabromofluorescein (HFinBr₄) to form ion association complex [Fe(bipy)₃]²⁺[(FinBr₄)₂]²⁻ which can emit phosphorescent signal on filter paper substrate. Under the optimum condition, the linear dynamic range of this method is 1.6-16 fg per spot with a detection limit (LD) of 0.18 fg per spot (0.4 μl sample solution per spot), and the regression equation of working curve is ΔI_p=1.058+7.671 C_Hg²⁺ (fg per spot ), n=7, correlation coefficient is 0.9990. This method has been applied to the determination of trace mercury in hair and cigarette samples with satisfactory result. The reaction mechanism for formation of the ion association complex is also discussed.     

Determination of polybrominated diphenyl ethers in human hair by gas chromatography-mass spectrometry

A rapid analytical method has been developed for the determination of polybrominated diphenyl ethers (PBDEs) in human hair. PBDEs were determined by gas chromatography with electron ionization mass spectrometric detection in the selected ion monitoring mode (GC-MS-SIM). A 200 mg amount of hair samples was overnight digested in 3N HCl and then PBDEs extracted with n-hexane. After clean up of extracts in a Florisil column, PBDEs were analyzed by GC-MS. The method has been validated by spiking human hair at five concentration levels, in the range from 5 to 25 ng/g for most compounds, and PBDEs were quantified using labelled compounds as internal standards. Recoveries of PBDEs were higher than 90%, repeatability was equal or lower than 12.5%, and reproducibility lower than 14%, expressed as relative standard deviation (RSD). Limits of detection (LOD) were in the range 0.08-0.9 ng/g and limits of quantification (LOQ) were between 0.27 and 3.0 ng/g. This method was applied to the determination of PBDEs in hair samples from 16 individuals and 5 PBDE congeners were detected in most of the samples. BDE-209 was the dominant compound found, followed by BDE-47, BDE-99, BDE-100, and BDE-190. BDE-209 was found in 12 out of 16 hair samples, and the total levels of PBDEs ranged from 1.4 to 19.9 ng/g.     

Solid-phase microextraction with simultaneous oxidative sample treatment for the sensitive determination of tetra- to hexa-brominated diphenyl ethers in sediments

Solid-phase microextraction (SPME) is an effective technique for the extraction of polybrominated diphenyl ethers (PBDEs) from environmental water samples. Although it has been also applied to sediments, the organic content of this matrix causes an exponential decrease in the yield of the extraction. This work presents an improved SPME procedure for the sensitive determination of six PBDEs (tetra- to hexa-brominated congeners) in sediments containing up to 6% of total organic carbon (TOC). Samples (0.25–0.5 g) were accurately weighed in 22 mL glass vessels, mixed with a given amount of potassium permanganate, 0.5 mL of sulphuric acid and 5 mL of water. Extractions were performed at 100 °C, for 40 min, using a polyacrylate (PA) coated fibre in the headspace (HS) mode. Potassium permanganate showed a dramatic, positive effect on the yield of the extraction. Its optimum amount was related to the TOC of the sediment, with overall highest responses attained for 40 mg of oxidant per mg of organic carbon in the SPME vessel. Under final working conditions, the combination of SPME with gas chromatography coupled to tandem mass spectrometry (GC–MS/MS) provided relative standard deviations (RSDs) below 14%, relative recoveries from 76 to 111% and limits of quantification (LOQs) lower than 0.15 ng g⁻¹ for all the investigated PBDEs in spiked river and marine sediments with different TOC. The performance of the method was also evaluated satisfactorily with a medium complexity (TOC 6.7%), real-life polluted sediment, previously analyzed in inter-laboratory comparison exercises.     

Challenges of gas chromatography-high-resolution time-of-flight mass spectrometry for simultaneous analysis of polybrominated diphenyl ethers and other halogenated persistent organic pollutants in environmental samples

The potential of a gas chromatographic method employing high-resolution time-of-flight (TOF) mass spectrometry was evaluated for detection of polybrominated diphenyl ethers (PBDEs) in the environmental matrices represented by fish and river sediment. Two ionisation techniques, viz. electron ionisation (EI) and negative ion chemical ionisation (NICI), the latter with methane as a reagent gas, were used in this study. While the instrumental lowest calibration levels (LCLs) obtained in El were in the range from 1 to 5 pg, their values ranged between 10 to 250 fg in NICI mode. This enhancement in detectability of target analytes enabled identification/quantification of even minor PBDE congeners, and consequently, improved characterisation of particular sample contamination patterns. In addition, this method allowed estimation of the PCB levels in examined samples. CB 153 was used as a contamination marker in this study.     

Bisphosphine monoxides with o-phenylene backbones in Pt,Pd and Fe complexes

A new route to aromatic bisphosphine monoxides has been explored through ortholithiation of triphenylphosphine oxide and subsequent reaction of the lithiated intermediate with a range of alkyl and aryl phosphine chlorides. Routes to the known bisphosphine monoxide (BMPO) (o-C₆H₄){P(O)Ph₂}PPh₂ (2aO) and a range of new BPMOs of the type Ph₂P(O)(o-C₆H₄)PR₂ where R₂ = ⁱPr₂, Cy₂, Et₂ are described. Reaction of 2aO with MCl₂(cod) (M = Pd, Pt; cod = cyclooctadiene) gives products of the form [MCl(κ¹-P-2aO)(κ²-P,O-2aO)]⁺ Cl⁻ and MCl₂(κ²-P,O-2aO); the former exhibits fluxional behaviour which has been analysed by ¹⁹⁵Pt NMR and ³¹P variable-temperature NMR spectroscopy. The bidentate complex is not fluxional for either the Pd or the Pt example; the Pt complex PtCl₂(κ²-P,O-2aO) has been characterised by X-ray crystallography. By comparison of the product distribution seen by ³¹P NMR spectroscopy and ESI-MS it was established that the different coordination modes of 2aO result in quite different behaviour of the complexes when studied by ESI-MS; when the O is formally coordinated to the metal its ionisation efficiency is very low. Synthesis of Fe(CO)₄(2aO) confirmed the ability of the 2aO ligand to render a neutral complex with no alternative pathways for ionisation to be readily detected by ESI-MS.