Pressurised membrane-assisted liquid extraction of UV filters from sludge

A method for the determination of 11 UV-filter compounds in sludge has been developed and evaluated. The procedure includes the use of non-porous polymeric membranes in combination with pressurised liquid extraction (PLE). Firstly, the solid sample, wetted with the extraction solvent, was enclosed into tailor-made bags prepared with low density polyethylene. Secondly, these packages were submitted to a conventional PLE (70 °C, 4 cycles of 5 min static time). Finally, the analytes were determined by liquid chromatography–atmospheric pressure photoionisation–tandem mass spectrometry. The main advantage of this procedure is the reduction of time, solvent and labour effort ought to the combination of extraction and clean-up in a single step. Although the extraction is not quantitative (thus, standard addition is recommended for quantification) selectivity is clearly gained using the membrane as a consequence of the differences of permeation and transport through the membrane between the analytes and other sample matrix components. The optimised protocol provides limits of detection ranging from 0.3 ng g⁻¹ (ethylhexyl dimethyl p-aminobenzoate (OD-PABA)) to 25 ng g⁻¹ (ethylhexyl triazone (EHT)) with only 0.5 g of sludge sample. All the studied UV filters were found in the samples at concentration levels between 1.4 and 2479 ng g⁻¹, emphasising the high adsorption potential of this kind of environmental pollutants onto solid samples such as sludge. Also, this method has permitted the determination of seven of the studied UV filters in sludge samples for the first time.     

Dimeric aluminum-phosphorus compounds as masked frustrated Lewis pairs for small molecule activation

Hydroalumination of aryldialkynylphosphines RP(C≡C-(t)Bu)(2) (R = Ph, Mes) with equimolar quantities of diethylaluminum hydride afforded mixed alkenyl-alkynyl cyclic dimers in which the dative aluminum-phosphorus bonds are geminal to the exocyclic alkenyl groups. Addition of triethylaluminum to isolated 1 (R = Ph) or to the in situ generated species (R = Mes) caused diethylaluminum ethynide elimination to yield the arylethylphosphorus dimers 2 and 3. These possess a chair-like Al(2)C(2)P(2) heterocycle with intermolecular Al-P interactions. The boat conformation (4) was obtained by the reaction of (t)Bu-P(C≡C-(t)Bu)(2) with di(tert-butyl)aluminum hydride. Despite being dimeric, 2 behaves as a frustrated Lewis pair and activates small molecules. The reaction with carbon dioxide gave cis/trans isomeric AlPC(2)O heterocycles that differ only by the configuration of the exocyclic alkenyl unit. Four isomers resulted from the reaction with phenyl isocyanate. This is caused by cis/trans isomerization of the initial C=O adduct and subsequent rearrangement to the AlPC(2)N heterocycle, being the C=N adduct.     

High resolution LAPS and SPIM

The resolution of photocurrent measurements at field-effect capacitors as used in light-addressable potentiometric sensors (LAPS) and scanning photo-induced impedance microscopy (SPIM) has been investigated using silicon on sapphire (SOS) substrates illuminated at different wavelengths. Using a two-photon effect in silicon (λ = 1250 nm) to generate the photocurrent, genuine submicrometer resolution has been demonstrated for LAPS and SPIM. Improved sensitivity for both LAPS and SPIM was obtained using a 6.7 nm thick gate oxide on SOS anodically grown in 0.1 M HCl.     

LaI2@(18,3)SWNT: the unprecedented structure of a LaI2 "Crystal," encapsulated within a single-walled carbon nanotube.

The novel crystallization properties of nano-materials represent a great challenge to researchers across all disciplines of materials science. Simple binary solids can be found to adopt unprecedented structures, when confined into nanometer-sized cavities, such as the inner cylindrical bore of single-walled carbon nanotubes (SWNT). Lanthanum iodide was encapsulated within SWNTs and the resulting encapsulation composite was analyzed using energy-dispersive X-ray microanalysis (EDX) and high-resolution transmission electron microscopy (HRTEM) imaging techniques, to reveal a one-dimensional crystal fragment, with the stoichiometry of LaI2, crystallizing in the structure of LaI3 with one third of the iodine positions unoccupied. A complete characterization of the encapsulation composite was achieved using an enhanced image restoration technique, which restores the object wave from a focal series of HRTEM images, providing information about the precise structural data of both filling material and host SWNT, and thereby enabling the identification of the SWNT chirality.     

Measurements by gas chromatography/pyrolysis/mass spectrometry: fundamental conditions in (2)H/(1)H isotope ratio analysis

Gas chromatography/pyrolysis/isotope ratio mass spectrometry (GC/P/IRMS) is a relatively new method for on-line determination of (2)H/(1)H isotope ratios. The influence of different parameters on the (2)H/(1)H isotope ratios obtained in GC/P/IRMS has been thoroughly studied using several flavor compounds, such as 5-nonanone, linalool, menthol, linalyl acetate and 4-decanolide. The requirement of "conditioning" the pyrolysis reactor to obtain reliable delta(2)H(V-SMOW) values is discussed. Furthermore, the influence of the carrier gas flow of the gas chromatograph on the completeness of pyrolysis and subsequently on the delta(2)H(V-SMOW) values is investigated in detail. The linear range of the compounds investigated is determined. The results show that calibrating the GC/P/IRMS system with secondary standard substances is absolutely necessary in order to obtain reliable delta(2)H(V-SMOW) values. In view of interlaboratory comparability, validation procedures are recommended.     

Organic surface modification and analysis of titania nanoparticles for self-assembly in multiple layers

The characteristics of TiO₂ coatings can greatly influence their final performance in large-scale applications. In the present study, self-assembly of TiO₂ nanoparticles (NPs) in multiple layers was selected as a deposition procedure on various substrates. For this, the main prerequisite constitutes the surface modification of both NPs and substrate with, for example, silane coupling agents. A set of functionalized TiO₂ NPs has been produced by reaction with either (3-aminopropyl)triethoxysilane (APTES) or (3-aminopropyl)phosphonic acid (APPA) to functionalize the NP surface with free amino-groups. Then, the complementary functionalized NP set can be obtained from an aliquot of the first one, through the conversion of free surface amino groups to aldehydes by reaction with glutaraldehyde (GA). Several types of TiO₂ NPs differing in size, shape, and specific surface area have been functionalized. Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), SEM/ energy-dispersive X-ray spectroscopy (EDS), XPS, Auger electron spectroscopy (AES), and Time-of-Flight (ToF)-SIMS analyses have been carried out to evaluate the degree of functionalization, all the analytical methods employed demonstrating successful functionalization of TiO₂ NP surface with APTES or APPA and GA.     

Wet‐Chemical Synthesis of Nanoscale Iron Boride,XAFS Analysis and Crystallisation to α‐FeB

The reaction of lithium tetrahydridoborate and iron bromide in high boiling ether as reaction medium produces an ultrafine, pyrophoric and magnetic precipitate. X‐ray and electron diffraction proved the product to be amorphous. According to X‐ray absorption fine structure spectroscopy (XAFS) the precipitate has FeB structure up to nearly two coordination spheres around an iron absorber atom. Transmission electron microscopy (TEM) confirms the ultrafine powder to be nanoscale. Subsequent annealing at 450 °C causes the atoms to arrange in a more distinct FeB structure, and further thermal treatment to 1050 °C extends the local structure to the α‐modification of FeB. Between 1050 °C and 1500 °C α‐FeB is transformed into β‐FeB.