A new liquid chromatography/mass spectrometry method for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in urine

4‐(Methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK) is a carcinogenic nitrosamine produced upon curing tobacco. It is present in tobacco smoke and undergoes metabolism to 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol (NNAL) in the lungs. NNAL undergoes further uridine diphosphate glucuronosyltransferase (UGT)‐mediated metabolism to give N‐ and O‐glucuronide metabolites, which together with free (non‐conjugated) NNAL are then excreted in the urine. The ability to conduct validated analyses of free and conjugated NNAL in human urine is important in order to assess inter‐individual differences in lung cancer risk from exposure to cigarette smoke. The use of stable isotope dilution (SID) methodology in combination with liquid chromatography/multiple reaction monitoring/mass spectrometry (LC/MRM‐MS) provides the highest bioanalytical specificity possible for such analyses. We describe a novel derivatization procedure, which results in the formation of a pre‐ionized N‐propyl‐NNAL derivative. The increased LC/MS sensitivity arising from this derivative then makes it possible to analyze free NNAL in only 0.25 mL urine. This substantial reduction in urine volume when compared with other methods that have been developed will help preserve the limited amounts of stored urine samples that are available from on‐going longitudinal biomarker studies. The new high sensitivity SID LC/MRM‐MS assay was employed to determine free and conjugated NNAL concentrations in urine samples from 60 individual disease‐free smokers. Effects of inter‐individual differences in urinary creatinine clearance on NNAL concentrations were then assessed and three metabolizer phenotypes were identified in the 60 subjects from the ratio of urinary NNAL glucuronides/free NNAL. Poor metabolizers (PMs, 14 subjects) with a ratio of NNAL glucuronides/free NNAL <2 (mean = 1.3), intermediate metabolizers (IMs, 36 subjects) with a ratio between 2 and 5 (mean = 3.4), and extensive metabolizers (EMs, 10 subjects) with a ratio >5 (mean = 11.1). Copyright © 2010 John Wiley & Sons, Ltd.     

Solid-state detection of gases by use of thin films based on pyrazole units, and morphological characterization of the films by AFM

Synthesis of a series of heterocyclic compounds based on pyrazole units is reported. The possibility of using these compounds, as solid-state thin layers deposited on quartz substrates, for optical recognition of hazardous pollutant gases was investigated. The gases SO₂, NO₂, CO, CH₄, and NH₃ were studied. Two of the ligand layers had reversible sensitivity toward SO₂, with good reaction time. The presence of CO, CH₄ NO₂, and NH₃ had no effect on the optical properties. Morphological characterization by use of AFM microscopy was also investigated.     

Determination of rotation vectors from multi-point data and practical applications

The present work aims to present a different set of parameters for Euclidean motions which have a definite physical interpretation. The orientation here is obtained via vector-parameters which are elements of a Lie group with a nice and clear composition law. The method is quite convenient for describing of rigid body and manipulators motions such as scene and image processing and recognition. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Multi-syringe flow injection solid-phase extraction system for on-line simultaneous spectrophotometric determination of nitro-substituted phenol isomers

In this paper, a time-based multi-syringe flow injection (MSFI) approach is proposed for automated disk-based sorbent extraction of three nitro-substituted phenol isomers (2-, 3-, and 4-nitrophenol) followed by on-line simultaneous determination of individual species by diode-array spectrophotometry. The method involves the on-line enrichment of the targeted analytes from an acidic medium containing 0.1 mol L⁻¹ HCl onto a co-polymeric sorbent material, and the concurrent removal of potentially interfering matrix components. The nitrophenol isomers are subsequently eluted with an alkaline solution (0.7 mol L⁻¹ NaOH), whereupon the eluate is delivered to a diode-array spectrophotometer for recording of the spectral data in the UV-vis region. Deconvolution of strongly overlapped spectra was conducted with multivariate regression models based on multiple linear regression calibration. The analytical performance of the chemometric algorithm was characterized by relative prediction errors and recoveries.The MSFI manifold was coupled to a multiposition selection valve to set a rugged analyzer that ensures minimum operational maintenance via exploitation of membrane switching protocols. As compared with earlier methods for isolation/pre-concentration of nitro-substituted phenols based on liquid-liquid extraction, the proposed flow-through disk-based system should be regarded as an environmentally friendly approach because the use of harmful organic solvents is circumvented. Under the optimized chemical and physical variables, the 3σ_blank detection limits for 2-, 3-, and 4-nitrophenol were 1.2, 3.2 and 0.3 μmol L⁻¹ for a sample loading volume of 1.5 mL, and the relative standard deviations were ≤5.0%. The flowing system, which is able to handle up to 135 samples automatically, was proven suitable for monitoring trace levels of the target isomers in mineral, tap, and seawater.     

Pure two-dimensional polarization patterns for holographic recording

Two-dimensional (2D) polarization patterns are achieved by the interference of two pairs of beams with perpendicular planes of incidence and orthogonal polarizations (i.e. linear or circular). In both cases, imposing a phase shift of π/2 between consecutive beams contains the amplitude modulation of the optical field in the superposition region and, thus, pure 2D polarization patterns are created. The recording of these interference fields in a polarization-sensitive material, namely an amorphous azopolymer, creates reconfigurable 2D periodic microstructures with peculiar diffraction properties.     

Study of titania nanorod films deposited by matrix-assisted pulsed laser evaporation as a function of laser fluence

The effects of annealing at 300 °C on gold nanostructures sputtered onto glass substrate were studied using XRD, SAXSees, the Van der Pauw method and ellipsometry. As-sputtered and annealed samples exhibit a different dependence of the gold lattice parameter on the sputtering time. With increasing sputtering time the average thickness of the layer and the size of gold crystallites increased. Another rapid enlargement of the crystallites is observed after annealing. The volume resistivity decreases rapidly with the increasing sputtering time for both, as-deposited and annealed structures. With increasing sputtering time initially discontinuous gold coverage changes gradually in a continuous one. Electrically continuous gold coverage on the as-sputtered and annealed samples exhibits the same concentration of free charge carriers and Hall mobility. Optical constants of as-deposited and annealed gold films determined by ellipsometry support resistivity measurements and clearly manifest the presence of plasmons in discontinuous films.     

Hydroxycarbonylation of 1-hexene catalyzed by [Rh(COD)(amine)2](PF6) complexes immobilized on poly(4-vinylpyridine)

Summary Rhodium(I) complexes, [Rh(COD)(amine)₂](PF₆) (COD = 1,5-cyclooctadiene, amine = 4-picoline, 3-picoline, 2-picoline, pyridine, 3,5-lutidine or 2,6-lutidine) immobilized on poly(4-vinylpyridine) in contact with water catalyzed both the hydroxycarbonylation of 1-hexene to propionic acid and the water-gas shift reaction (WGSR). The role of the coordinated amine on the catalytic activity was examined.     

Homogeneous Catalytic Oxidation of Cyclohexene by Nitro Complexes of Copper(II)

This work describes the preliminary study of the homogeneous oxidation reaction of cyclohexene by nitro complexes of copper(II), Cu(CH₃CN)₂(NO₂)Cl (1) and Cu(CH₃CN)₂(NO₂)₂ (2) in acetonitrile, under oxygen pressure (20 atm) at 70 and 100°C. The results show the formation of 2-cyclohexen-1-one and 1,2-epoxyhexane-3-one as main reaction products. Also, it was observed that the oxidation reaction at 100°C with complexes 1 and 2 becomes more selective to the formation of 2-cyclohexene-1-one although the activity of both catalyst decreases.     

Modified RP-LC of Phenylthiocarbamyl Amino Acid Adducts in Plasma Acetonitrile Extracts Using Multiple Internal Standards and Photo-Diode UV Detection

Among the techniques available for quantitative analysis of physiological amino acids, systems using optical detection are of low specificity because of possible interference at the analytical wavelength. Another disadvantage is problems of sample extraction from complex biological matrices, for example plasma. This paper describes reversed-phase LC of phenylthiocarbamyl (PTC) amino acids in plasma deproteinated by addition of acetonitrile. Specificity was monitored by photo-diode UV detection and accuracy was assessed by a plasma spiking procedure with more than one internal standard. Dual-wavelength spectrophotometry (254 and 283 nm) was also used for separate measurement of co-eluting adducts of tryptophan and ornithine. This method enables the quantification, with high reproducibility, of a total of twenty-three plasma amino acids from fasting healthy subjects. LOQ values are satisfactory for all the amino acids (average 6 μmol L^?1). However, the method does not enable analysis of aspartate and overall homocystine, present at very low concentrations, in all plasma samples. This PTC–amino acid chromatographic method is inexpensive, reliable, and suitable for clinical research and therapeutic drug monitoring, but adaptation to dual on-line detection is required to improve its sensitivity.     

Electrical and optical properties of ITO and ITO/Cr-doped ITO films

In this paper we report on the effects of the insertion of Cr atoms on the electrical and optical properties of indium tin oxide (ITO) films to be used as electrodes in spin-polarized light-emitting devices. ITO films and ITO(80 nm)/Cr-doped ITO(20 nm) bilayers and Cr-doped ITO films with a thickness of 20 nm were grown by pulsed ArF excimer laser deposition. The optical, structural, morphological and electrical properties of ITO films and ITO/Cr-doped structures were characterized by UV–Visible transmission and reflection spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Hall-effect analysis. For the different investigations, the samples were deposited on different substrates like silica and carbon coated Cu grids. ITO films with a thickness of 100 nm, a resistivity as low as ～4×10^?4 Ω?cm, an energy gap of ～4.3 eV and an atomic scale roughness were deposited at room temperature without any post-deposition process. The insertion of Cr into the ITO matrix in the upper 20 nm of the ITO matrix induced variations in the physical properties of the structure like an increase of average roughness (～0.4–0.5 nm) and resistivity (up to ～8×10^?4 Ω?cm). These variations were correlated to the microstructure of the Cr-doped ITO films with particular attention to the upper 20 nm.