Paul Bendig

Photolytical transformation rates of individual polybrominated diphenyl ethers in technical octabromo diphenyl ether (DE-79).

Polybrominated diphenyl ethers (PBDEs) are of environmental concern due to their persistence, potential to bioaccumulate, and possible toxic effects, especially for the lower brominated homologues. Reductive debromination under UV light has been identified as the main abiotic pathway for PBDE transformation. Although the kinetics and transformation products have been determined for individual PBDE congeners in different matrices, no effort has been made to determine the kinetics of these congeners when technical mixtures are exposed to UV light. We irradiated technical octabromodiphenyl ether (DE-79) in a perdeuterated solvent to determine the photolytic transformation kinetics of native PBDE congeners. Each deuterium that replaced bromine resulted in a shift to higher masses compared to the native congener, which was measured by gas chromatography with electron ionization mass spectrometry in the selected ion monitoring mode (GC/EI-MS-SIM). Tri-, tetra-, and pentabromodiphenyl ether products (BDE 28, BDE 47, BDE 49, BDE 99, BDE 100) could be proportioned to higher brominated precursors as a function of irradiation time. The kinetics of UV-irradiated single PBDE congeners matched well with results of previous studies of single congeners. However, when the same congeners were irradiated in the technical DE-79 mixture, their half-lives were longer by 20-160%. This study indicates that individually irradiated PBDE congeners behave differently than if present as a mixture. This result should be taken into account in models predicting the environmental fate of PBDEs and most likely also the mixtures of other contaminant groups.

Determination of Glyphosate Levels in Breast Milk Samples from Germany by LC-MS/MS and GC-MS/MS

This study describes the validation and application of two independent analytical methods for the determination of glyphosate in breast milk. They are based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS), respectively. For LC-MS/MS, sample preparation involved an ultrafiltration followed by chromatography on an anion exchange column. The analysis by GC-MS/MS involved an extraction step, cleanup on a cation exchange column, and derivatization with heptafluorobutanol and trifluoroacetic acid anhydride. Both methods were newly developed for breast milk and are able to quantify glyphosate residues at concentrations as low as 1 ng/mL. The methods were applied to quantify glyphosate levels in 114 breast milk samples, which had been collected from August to September of 2015 in Germany. The mothers participated at their own request and thus do not form a representative sample. In none of the investigated samples were glyphosate residues above the limit of detection found.

UV-Induced Formation of Bromophenols from Polybrominated Diphenyl Ethers

Bromophenols (BPs) are both man-made industrial compounds and naturally produced secondary metabolites of algae and sponges. This study explored the formation of BPs by UV irradiation of polybrominated diphenyl ethers (PBDEs). Simulated sunlight (10-80 min) and natural sunlight irradiations (5 days) of BDE-153, BDE-154, BDE-183, BDE-196, and technical octabromodiphenyl ether (DE-79) generated hydrodebrominated PBDEs along with up to 0.7-4 mass % BPs. UV absorption spectra were recorded to show that the para-substituted PBDEs and BPs are those predominately transformed because this structural feature causes a significant bathochromic shift of λmax to higher wavelength. A decrease of higher brominated BPs in favor of lower brominated BPs was observed with time. All possible substitution patterns on the BPs formed by the cleavage of the parent PBDEs and respective hydrodebromination products were observed. The main di- and tribromophenols detected were 2,4-diBP > 2,5-diBP and 2,4,6-triBP > 2,4,5-triBP on average. The irradiation conditions were similar to real-world scenarios and emphasized the environmental relevance of these photolysis products of PBDEs. The meta-substituted BPs can be used as markers to distinguish photolytic PBDE transformation products from naturally produced BPs, which exclusively feature bromo-substitutents in ortho- and para-positions.

Stable carbon isotope analysis (δ13C values) of polybrominated diphenyl ethers and their UV-transformation products

Polybrominated diphenyl ethers (PBDEs) are frequently detected in food and environmental samples. We used compound specific isotope analysis to determine the δ(13)C values of individual PBDEs in two technical mixtures. Within the same technical product (DE-71 or DE-79), BDE congeners were the more depleted in (13)C the higher brominated they were. In contrast, the products of light-induced hydrodebromination of BDE 47 and technical DE-79 were more enriched in (13)C because of more stable bonds between (13)C and bromine. As a result, the δ(13)C values of the irradiated solution progressed diametrically compared to those of the technical synthesis. The ratio of the δ(13)C values of BDE 47 to BDE 99 and of BDE 99 to BDE 153 are thus suggested as indicators to distinguish native technical products from transformation products. Ratios <1 are typical for native congeners (e.g. in DE-71) while the reversed ratio (>1) is typical of transformation products.

Fate of Polybrominated Diphenyl Ethers during Cooking of Fish in a New Model Cooking Apparatus and a Household Microwave

Fish is a major source of human exposure to polybrominated diphenyl ethers (PBDEs). Because fish is mainly consumed after cooking, this measure may alter the pattern and amounts of PBDEs that are finally consumed. To investigate this issue, we developed a model cooking apparatus consisting of a small glass bowl and a beaker glass with an exhaust fitted with a polyurethane foam filter connected to a water jet pump. In this model cooking apparatus, fish (1 g) and/or sunflower oil (0.2/0.4 g) spiked with three PBDE congeners was cooked for 30 min. Small amounts of the semi-volatile PBDEs were evaporated from the fish (BDE-47 < BDE-15), while the non-volatile BDE-209 was partly transformed. Additional experiments in a household microwave provided similar results, except that no transformation was observed for BDE-209. The model cooking apparatus proved to be well-suited to study the fate of polyhalogenated compounds in fish during cooking.

Identification of the natural product 2,3,4,5-tetrabromo-1-methylpyrrole in Pacific biota, passive samplers and seagrass from Queensland, Australia.

Halogenated natural products (HNPs) are frequently detected in marine organisms. High HNP concentrations have previously been found in marine mammals from the Great Barrier Reef, Australia, including in the blubber of herbivorous dugongs (Dugong dugon). To identify the source of HNPs we initially focused on the analysis of Australian seagrass (Halophila ovalis) which serves as the principal food source for dugongs. GC/MS analysis of the seagrass indicated the presence of several organobromine compounds. One compound was identified as 2,3,4,5-tetrabromo-1-methylpyrrole (TBMP) by synthesis. Subsequent analysis of semipermeable membrane devices demonstrated that the photo-sensitive TBMP is widespread in the Great Barrier Reef (Queensland, Australia). The detection of larger TBMP concentrations in fish fillets from Chile and traces in mussels from New Zealand indicated that this potential HNP may be distributed throughout the Southern Pacific Ocean.

Mass spectra of methyl esters of brominated fatty acids and their presence in soft drinks and cocktail syrups

RATIONALE Brominated vegetable oil (BVO) is frequently used as a solubility transmitter in soft drinks. Being banned in Europe and Japan but permitted in the United States and Canada, there is a need for analytical methods suitable for use in food control. Brominated fatty acids in BVO are usually determined by gas chromatography (GC) after their conversion into the corresponding methyl esters. METHODS GC with mass spectrometry (MS) was used to record the electron ionization (EI) and negative ion chemical ionization (NICI) mass spectra of relevant brominated fatty acid methyl esters synthesized for this purpose. Brominated fatty acids obtained from transesterified BVO from soft drink and syrup samples were also analyzed. RESULTS GC/NICI-MS was the most sensitive method for the detection of brominated fatty acids but GC/EI-MS was found to be more suited for quantification due to the formation of more selective fragment ions in the higher mass range. Suitable ions were selected for determination of the methyl esters of brominated fatty acids in the selected ion monitoring (SIM) mode. Artifacts produced by the transesterification of BVO with boron trifluoride were observed and discussed. BVO was also quantified in three syrup samples commercially produced for use in cocktails/long drinks. In one of the syrup samples that tested positive, BVO was not labelled in the ingredient list. Bromination experiments produced evidence that one or more Br2 -18:0 isomers identified as a shoulder peak of threo-9,10-dibromooctadecanoic acid in several soft drink and syrup samples originated from the bromination of partly hydrogenated plant oil. CONCLUSIONS BVO was determined for the first time in syrup samples. Attention should be paid to the problem of BVO occurring unlabeled in soft drinks and cocktail syrups imported from North America.

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%.

Synthesis of polychlorinated terphenyl mixtures and gas chromatography with mass spectrometry data of tetra- to octachlorinated ortho-, meta-, and para-terphenyls

Polychlorinated terphenyls (PCTs) are a class of polyhalogenated compounds previously used in similar applications as polychlorinated biphenyls (PCBs). According to present knowledge all industrial production was closed in the 1970s. The total PCT manufacture reached about 5% of the production of PCBs. Unlike the PCBs, PCTs have been scarcely analyzed in environmental samples mostly due to analytical difficulties. PCTs were synthesized by the chlorination of technical terphenyl which consists of ortho-, meta- and para-terphenyls. This procedure led to very complex mixtures of polychlorinated compounds whose composition, especially with regard to the terphenyl backbones, remained unknown. Here we report the individual chlorination of the three terphenyl backbones to mixtures of Tetra- to OctaCTs, respectively. The average degree of chlorination of the ortho-, meta- and para-PCTs ranged from 6.8 to 7.4. These products were analyzed by gas chromatography with mass spectrometry in electron ionization (GC/EI-MS) and electron capture negative ion (GC/ECNI-MS) modes. The elution order of isomers was ortho-PCTs≪meta-PCTs<para-PCTs. In both GC/MS modes, the mass spectra of ortho-PCTs differed from those of the meta- and para-homologues in that the molecular ion was less prominent (GC/EI-MS) or very frequently absent (GC/ECNI-MS). In addition, the relative GC/ECNI-MS responses of para-PCTs were on average higher compared with meta- and ortho-PCTs.

Quantification of bromophenols in Islay whiskies.

Two single malt whiskies from the Scottish island Islay, i.e., Laphroiag and Lagavulin, are characterized by an iodine-like flavor associated with marine environments. In this study we investigated if this flavor impression could be due to bromophenols which are character impact compounds of marine fish and shrimps. In this study we developed a method suited for the determination of dibromo- and tribromophenols in whisky. Aliquots were O-acetylated, and quantification was carried out with gas chromatography with electron-capture negative ion mass spectrometry (GC/ECNI-MS). Both Islay whiskies contained more than 400 ng/L bromophenols with 2,6-dibromophenol being the most relevant homologue (>300 ng/L, respectively). These concentrations are at least 1 order of magnitude higher than the taste threshold of 2,6-dibromophenol in water. A third Islay whisky, Bowmore, contained ∼100 ng/L bromophenols while seventeen other whiskies from other regions in Scotland as well as from the USA, Ireland, and Germany contained at least 1 order of magnitude less than the two whiskies with the marine taste. Accordingly, bromophenols may contribute to the marine flavor and taste of Laphroaig and Lagavulin.