Quantification of polycyclic aromatic hydrocarbons in the NIST standard reference material (SRM1649A) urban dust using thermal desorption GC/MS

A thermal desorption GC/MS technique has been developed for the quantification of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter using the NIST Standard Reference Material (SRM1649a) Urban Dust. The technique was developed using standard linearity tests in order to establish optimum sample weights and optimum desorption and chromatographic parameters. This direct analysis technique eliminates the use of solvents in the sample preparation (reducing volatile component losses) and also significantly reduces the sample preparation time (no extraction procedure). The technique has been shown to give linearity in terms of the overall TIC response as well as for a prominent series of n-alkanes (C20-C33) and 10 NIST priority PAHs, 8 of which have been quantified. The technique is reported to be uniquely sensitive (PAH concentrations 2-6 mg kg(-1)) and reproducible (MW = 178-228 SD < or =0.228 mg kg(-1), < or =7%; MW = 252 SD < or =0.922 mg kg(-1), < or =33%) over the range of sample weights (1-5 mg). Such sample weights illustrate that the technique can be equally applied to the analysis of airborne particulate samples collected over short time periods (24-48 h) using only commonly used low-volume collection devices.     

Power spectral density analysis of optical substrates for gravitational-wave interferometry

The power spectral density of surface-relief variations on polished optical surfaces across microscopic through to macroscopic spatial scales is calculated from measurements on substrates that are being produced for the Laser Interferometer Gravitational-Wave Observatory (LIGO). These spectra give a guide to the scattering properties of the surface, which in turn critically influence the performance of LIGO. Measurements obtained by use of a full-aperture interferometer and an interference microscope with two different objectives are combined to produce one-dimensional power spectral density representations of the surfaces across spatial frequencies ranging from 0.1 to 8000 cm(-1). These measurements from different instruments are in good agreement with an analytic power spectrum that varies as nu(-1.5), where nu is the spatial frequency. Some anomalies in the power spectral density spectra can be related to aspects of the polishing process.     

Potential mycotoxin problems in mould-fermented sausage

Summary A considerable proportion of the sausage consumed in many European countries is produced by a mould-fermentation process that does not involve pure culture technics.422Penicillium cultures isolated from mould-ripened sausages produced in II European countries were analyzed for their ability to produce the following nine mycotoxins: aflatoxin B₁ and G₁ ochratoxin A, penicillic acid, patulin, citrinin, tremortin A, zearalenone, rubratoxin B; 88 isolates were found capable of toxin synthesis (20.9%). 44 of these cultures produced penicillic acid, 17 ochratoxin A, 11 tremortin A, 10 citrinin, and 6 patulin. 3 cultures produced both patulin and citrinin.Sausages were ripened with 6 moulds producing penicillic acid, 17 producing ochratoxin, 5 producing citrinin and 3 each producing patulin or tremortin. No mycotoxins were detected up to 70 days of ripening.Direct addition of penicillic acid to raw sausage resulted in disappearance of the mycotoxin. Amino acids normally occuring in meat were found capable of rapidly reacting with penicillic acid to produce adducts that were nontoxic to laboratory animals.Although our data indicate that consumption of mould ripened sausage is not a health hazard with respect to the 9 mycotoxins analyzed for, it is recommended that manufacturers of these products adopt pure culture technics using moulds known to be toxicologically safe.

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Zusammenfassung In zahlreichen Ländern Europas werden seit altersher mit Schimmelpilzen gereifte Rohwürste hergestellt. Es handelt sich hierbei um traditionelle Produktionsverfahren, bei denen jedoch keine Schimmelpilz-Reinkulturen verwendet werden.Wir untersuchten das Toxinbildungsvermögen von 422Penicillium-Stämmen, die von schimmelpilzgereiften Rohwürsten isoliert worden waren, die aus II verschiedenen Ländern stammten. Insbesondere interessierten uns die Mykotoxine Aflatoxin B₁ und G₁, Ochratoxin A, Penicillinsäure, Patulin, Citrinin, Tremortin A, Zearalenon und Rubratoxin B. Bei 88 Stämmen (20,9%) war eine Toxinbildung nachweisbar. 44 dieser Kulturen bildeten Penicillinsäure, 17 Ochratoxin A, 11 Tremortin A, 10 Citrinin und 6 Patulin. Von drei Stämmen wurde sowohl Patulin als auch Citrinin gebildet.Wurden frisch hergestellte Rohwürste mit Schimmelpilzen, die die genannten Toxine bilden, beimpft, so konnten während der 70 Tage dauernden Reifung keine Mykotoxine in der Wurst nachgewiesen werden.Den Rohwürsten direkt zugesetzte Penicillinsäure wurde inaktiviert, da dieses Mykotoxin sehr rasch mit Aminosäuren reagiert, die im Fleisch vorhanden sind.Obwohldiese Untersuchungen darauf hinweisen, daß sehimmelpilzgereifte Rohwürste, zumindest bezüglich der 9 genannten Mykotoxine, keine potentielle Gefahr für den Verbraucher darstellen, sollte man dennoch dazu übergehen als Starterkultur nur technologisch und toxikologisch geprüfte Schimmelpilz-Stämme in Reinkultur einzusetzen.

     

Infrasorb: Optical detection of the heat of adsorption for high throughput adsorption screening of porous solids

The demand for fast screening methods in modern materials chemistry led to the development of a room temperature operated high-throughput tool for adsorption screening. Within five minutes a porosity screening of a large sample pool can be realized. Using a variety of different porous materials (activated carbons, porous polymers, metal-organic frameworks, zeolites) and the test gas n-butane, the reliability of the new instrument is shown. Furthermore, possible applications in the determination of n-butane capacities and BET surface areas are given as well as the application in synthesis or product control.The presented data exhibit high quality factors for the correlation of integrated signal intensity (heat of adsorption) and specific surface areas (above 0.97). As an example for the applicability of other gases that can be used with this tool, screening measurements using cyclohexane as test gas are also presented. The developed automated screening tool is an important step to overcome the bottle-neck between high-throughput syntheses technologies developed in the last decades and measurement of adsorption properties.     

High efficiency removal of dissolved As(III) using iron nanoparticle-embedded macroporous polymer composites

Novel nanocomposite materials where iron nanoparticles are embedded into the walls of a macroporous polymer were produced and their efficiency for the removal of As(III) from aqueous media was studied. Nanocomposite gels containing α-Fe₂O₃ and Fe₃O₄ nanoparticles were prepared by cryopolymerisation resulting in a monolithic structure with large interconnected pores up to 100 μm in diameter and possessing a high permeability (ca. 3 × 10⁻³ m s⁻¹). The nanocomposite devices showed excellent capability for the removal of trace concentrations of As(III) from solution, with a total capacity of up to 3 mg As/g of nanoparticles. The leaching of iron was minimal and the device could operate in a pH range 3-9 without diminishing removal efficiency. The effect of competing ions such as SO₄²⁻ and PO₄³⁻ was negligible. The macroporous composites can be easily configured into a variety of shapes and structures and the polymer matrix can be selected from a variety of monomers, offering high potential as flexible metal cation remediation devices.     

Resource efficiency and environmental impact of fiber reinforced plastic processing technologies

The process energy demand and the environmental indicators of two carbon fiber reinforced plastic process chains have been investigated. More precisely, the impact of different production set-ups for a standard textile preforming process using bindered non-crimp fabric (NCF) and a material efficient 2D dry-fiber-placement (DFP) process are analyzed. Both 2D preforms are activated by an infrared heating system and formed in a press. The resin-transfer-molding (RTM) technology is selected for subsequent processing. Within a defined process window, the main parameters influencing the process energy demand are identified. Varying all parameters, a reduction of 77% or an increase of 700% of the electric energy consumption compared to a reference production set-up is possible, mainly depending on part size, thickness, and curing time. For a reference production set-up, carbon fiber production dominates the environmental indicators in the product manufacturing phase with a share of around 72–80% of the total global warming potential (GWP). Thus, the reduction of production waste, energy efficient carbon fiber production, and the use of renewable energy resources are the key environmental improvement levers. For the production of small and thin parts in combination with long curing cycles, the influence of the processing technologies is more pronounced. Whereas for a reference production set-up, only 10% (NCF–RTM) and 15% (DFP–RTM) of the total GWP are caused by the processing technologies, a production set-up leading to a high process energy demand results in a share of 40% (NCF–RTM) and 49% (DFP–RTM), respectively.     

An Innovative Technique for Rapid Screening of Cigarette Filter Adsorbents

Cigarette smoke is an aerosol containing a large number of chemicals, including toxicants. In recent years, a number of cigarette filter additives have been evaluated for their toxicant filtration properties. Screening is a useful tool to accelerate the testing and development of new filter additives and filtration mechanisms. The evaluation of a filter material screening technique based on the so‐called InfraSORP technology is described. By comparing InfraSORP measurements with reference cigarette smoke experiments of potential cigarette filter materials like activated carbons and ion‐exchange resin, an excellent correlation is demonstrated. This technique allows for a rapid screening of potential filter materials prior to testing any final candidates in cigarettes.     

Production of penitrem A by Penicillium crustosum isolated from foodstuffs

Sixty one isolates of Penicillium crustosum originating from various foodstuffs were screened for penitrem A production by thin-layer chromatography. The highest producers of penitrem A (4 isolates) were grown in various liquid media. Skimmed milk (2%)/potato extract (2%)/sucrose (2%) (SPS) medium supported the highest toxin production and P. crustosum Sp 1552 was selected as the best producer of penitrem A. Optimal conditions for the production of penitrem A were to grow the isolate Sp 1552 (stationary) in 100 ml of SPS medium (with 4% sucrose) in 500-ml flasks for 3 weeks at 25 degrees C with initial pH 5.7. The isolation and purification of penitrem A is described. Approximately 246 mg of pure penitrem A was obtained from 200 flasks each containing 100 ml of SPS medium.