Identification of flame retardants in polyurethane foam collected from baby products

With the phase-out of PentaBDE in 2004, alternative flame retardants are being used in polyurethane foam to meet flammability standards. However, insufficient information is available on the identity of the flame retardants currently in use. Baby products containing polyurethane foam must meet California state furniture flammability standards, which likely affects the use of flame retardants in baby products throughout the U.S. However, it is unclear which products contain flame retardants and at what concentrations. In this study we surveyed baby products containing polyurethane foam to investigate how often flame retardants were used in these products. Information on when the products were purchased and whether they contained a label indicating that the product meets requirements for a California flammability standard were recorded. When possible, we identified the flame retardants being used and their concentrations in the foam. Foam samples collected from 101 commonly used baby products were analyzed. Eighty samples contained an identifiable flame retardant additive, and all but one of these was either chlorinated or brominated. The most common flame retardant detected was tris(1,3-dichloroisopropyl) phosphate (TDCPP; detection frequency 36%), followed by components typically found in the Firemaster550 commercial mixture (detection frequency 17%). Five samples contained PBDE congeners commonly associated with PentaBDE, suggesting products with PentaBDE are still in-use. Two chlorinated organophosphate flame retardants (OPFRs) not previously documented in the environment were also identified, one of which is commercially sold as V6 (detection frequency 15%) and contains tris(2-chloroethyl) phosphate (TCEP) as an impurity. As an addition to this study, we used a portable X-ray fluorescence (XRF) analyzer to estimate the bromine and chlorine content of the foam and investigate whether XRF is a useful method for predicting the presence of halogenated flame retardant additives in these products. A significant correlation was observed for bromine; however, there was no significant relationship observed for chlorine. To the authors knowledge, this is the first study to report on flame retardants in baby products. In addition, we have identified two chlorinated OPFRs not previously documented in the environment or in consumer products. Based on exposure estimates conducted by the Consumer Product Safety Commission (CPSC), we predict that infants may receive greater exposure to TDCPP from these products compared to the average child or adult from upholstered furniture, all of which are higher than acceptable daily intake levels of TDCPP set by the CPSC. Future studies are therefore warranted to specifically measure infants exposure to these flame retardants from intimate contact with these products and to determine if there are any associated health concerns.     

Comparison of a Quadrupole and a Time-of-Flight Aerosol Mass Spectrometer during the Feldberg Aerosol Characterization Experiment 2004

The Feldberg Aerosol Characterization Experiment (FACE-2004) took place from July 13–August 4, 2004 at the Taunus Observatory on the “Kleiner Feldberg” (825 m a.m.s.l.) in Central Germany. The experiment included (amongst others) size-resolved chemical characterization of non-refractory aerosol components. One of the experiment's objectives was to better understand and to characterize recently developed aerosol measurement instrumentation by intercomparison with other co-located instruments. One of these instruments was the Aerodyne Time-of-Flight Aerosol Mass Spectrometer (ToF-AMS).

Here we compare the datasets obtained by the ToF-AMS with those obtained by the well-characterized co-located Quadrupole Aerosol Mass Spectrometer (Q-AMS). A good agreement between the recently developed ToF-AMS with the established Q-AMS is reported here for all species measured with the two instruments for a time period where both instruments operated under well-calibrated conditions. During measurements with reduced detector gain after a pump failure changed species concentrations were measured with the ToF-AMS that did not agree with those measured with the Q-AMS. These changes were different for the individual species and could be attributed to the influence of the ion detection threshold as was shown by model calculations.

For efficient and user-friendly processing of ToF-AMS raw data a data processing software package was developed. Since this is the first time this software was used for field data, it is described in some detail here.     

Invasiveness of Listeria monocytogenes strains of Caco-2 cells in response to a period of extreme salt stress reflecting salt-curing and rehydration of cod (Gadus morhua L.)

Products like salt-cured fish contain approximately 15–21% NaCl and are rehydrated to 2–3% NaCl before preparation and consumption. These products are regarded as safe, but it has been shown that Listeria spp. is able to survive at extreme levels of salt and start to grow after rehydration. Thus, the ability of salt stressed Listeria monocytogenes to cause listeriosis, measured as its ability to invade Caco-2 cells was studied in this paper. Seven strains of L. monocytogenes and one Listeria innocua were cultivated in BHI to early and late stationary phase at 4 °C. At both phases, the strains were exposed to either no salt or to salt stress comparable to that applied in the production of rehydrated salt-cured cod, i.e. 21% NaCl followed by dilution to 2% NaCl. In addition, the eight strains were cultivated in BHI with 2% NaCl, which is similar to the salt content as in rehydrated salt-cured cod and other ready-to-eat (RTE) products as well. The ability of non salt stressed L. monocytogenes strains to enter Caco-2 cells was significant higher (p > 0.05) compared to the corresponding strains exposed to 21% NaCl for 96 h, followed by 2% NaCl for 48 h. On the other hand, L. monocytogenes cultivated in BHI with 2% NaCl showed a higher invasiveness of Caco-2 cells than both the other sample categories. As the ability to invade Caco-2 cells correlates with bacterial virulence, the results suggests that L. monocytogenes represent a lower food safety risk when exposed to salt-curing with extreme NaCl concentrations than exposure of a constant and moderate level of salt commonly used in RTE products.     

Protein Macrocyclization for Tertiary Structure Stabilization

Proteins possess unique molecular recognition capabilities and enzymatic activities, features that are usually tied to a particular tertiary structure. To make use of proteins for biotechnological and biomedical purposes, it is often required to enforce their tertiary structure in order to ensure sufficient stability under the conditions inherent to the application of interest. The introduction of intramolecular crosslinks has proven efficient in stabilizing native protein folds. Herein, we give an overview of methods that allow the macrocyclization of expressed proteins, discussing involved reaction mechanisms and structural implications.     

Rolling‐Circle Amplification: Unshared Advantages in miRNA Detection

Roll with it : The quantitative analysis of specific miRNAs from biological samples is very likely to revolutionize diagnostics of human disease. A novel method for miRNA analysis employing rolling‐circle amplification (RCA) can homogeneously detect miRNA, even at concentrations as low as 10 fM . The use of T4 RNA ligase 2 (T4 RnL2) at elevated temperatures enables very good discrimination of miRNAs differing by a single nucleotide.

     

Volumetric breast density estimation from full-field digital mammograms

A method is presented for estimation of dense breast tissue volume from mammograms obtained with full-field digital mammography (FFDM). The thickness of dense tissue mapping to a pixel is determined by using a physical model of image acquisition. This model is based on the assumption that the breast is composed of two types of tissue, fat and parenchyma. Effective linear attenuation coefficients of these tissues are derived from empirical data as a function of tube voltage (kVp), anode material, filtration, and compressed breast thickness. By employing these, tissue composition at a given pixel is computed after performing breast thickness compensation, using a reference value for fatty tissue determined by the maximum pixel value in the breast tissue projection. Validation has been performed using 22 FFDM cases acquired with a GE Senographe 2000D by comparing the volume estimates with volumes obtained by semi-automatic segmentation of breast magnetic resonance imaging (MRI) data. The correlation between MRI and mammography volumes was 0.94 on a per image basis and 0.97 on a per patient basis. Using the dense tissue volumes from MRI data as the gold standard, the average relative error of the volume estimates was 13.6%.     

Exclusive quantification of methyl-branched fatty acids and minor 18:1-isomers in foodstuff by GC/MS in the SIM mode using 10,11-dichloroundecanoic acid and fatty acid ethyl esters as internal standards

Minor fatty acids (iso- and anteiso-fatty acids, vaccenic acid, elaidic acid) in foodstuff (seafood, milk, and dairy products) were analyzed by gas chromatography with electron ionisation mass spectrometry in the selected ion monitoring mode (GC/EI-MS-SIM). For this purpose, lipids were obtained by accelerated solvent extraction (ASE) and the fatty acid constituents were converted into methyl esters. Instead of the determination of the relative contribution of the minor fatty acids to the sum of all fatty acids detected (the so-called 100% method), we exclusively quantified the minor fatty acids, which was possible by using two types of internal standards (IS-1 and IS-2). For recovery checks during the extraction and/or the transesterification step we added the novel 10,11-dichloroundecanoic acid (DC-11:0) as IS-1. DC-11:0, which has never been detected in foodstuff, was synthesized by electrophilic addition of chlorine to 10-undecenoic acid (11:1n-10). The novel IS eluted in the range of 23:0 from the polar GC column used and showed the same properties as fatty acids in foodstuff during sample preparation. Recovery rate of DC-11:0 was generally >96% in the various samples analyzed. Ethyl esters (FAEE) of a12:0, a14:0, a15:0, a16:0, a17:0, and a18:0 (IS-2) were added to both the external standard (a quantitative mixture of methyl esters of methyl-branched fatty acids and 18:1n-9trans) in order to determine their response factors relative to FAEE and to the food samples. With this technique, (only) methyl-branched fatty acids (MBFAs) as well as vaccenic acid (18:1n-7) and elaidic acid (18:1n-9trans) were quantified in a range of dairy products (including twelve cheeses) and seafood. All samples were analyzed in triplicates, and good standard deviations (concentrations 0.002–5 g/100 g; standard deviations 0.00–0.03) were obtained in all cases. MBFAs were detected in all samples analyzed. The highest content of MBFAs (3.0 g/100 g) was determined in red-smear of romadur cheese. In all except two cheeses, i17:0 was the most abundant MBFA. The highest amount of 18:1n-9trans was found in feta (2.84 g/100 g) whereas 0.03 g/100 g in big eye snapper (Pricanthus tayenus) marked the lowest record of this minor fatty acid. Seal oil contained the highest amount of 18:1n-7 with 5.00 g/100 g, whereas emmental cheese was the sample with the lowest content of this monoenoic fatty acid. The combination of suitable IS and a sensitive GC/EI-MS-SIM method proved to be well suited for the quantification of minor fatty acids in foodstuff. When only a set of fatty acids is going to be analyzed, this method is less time consuming compared to “100% methods” and less prone to false results due to the higher selectivity of GC/MS compared to GC in combination with flame ionisation detection (GC/FID).