Atmospheric Pressure Chemical Vapour Deposition of thin Films of Nb2O5 on Glass

A novel route involving atmospheric pressure chemical vapour deposition (APCVD) is reported for coating Nb2O5 onto glass substrates via the reaction of NbCl5 and ethyl acetate at 400-660degreesC. Raman spectroscopy is shown to be a simple diagnostic tool for the analysis of these thin films. The contact angle of water on Nb2O5-coated glass drops on UV irradiation from 60degrees to 5-20degrees. XPS Analysis showed that the Nb:O ratio of the film was 1:2.5. Glancing angle X-ray diffraction showed that all films were crystalline, with only a single phase being observed; this has some preferred orientation in the (201) plane of Nb2O5. The niobium(V) oxide materials show minimal photocatalytic ability to degrade organic material.

Characterisation of the photocatalyst Pilkington Activ (TM): a reference film photocatalyst?

Pilkington Glass Activ(TM) represents a possible suitable successor to P25 TiO2, especially as a benchmark photocatalyst film for comparing other photocatalyst or PSH self-cleaning films. Activ(TM) is a glass product with a clear, colourless, effectively invisible, photocatalytic coating of titania that also exhibits PSH. Although not as active as a film of P25 TiO2, Activ(TM) vastly superior mechanical stability, very reproducible activity and widespread commercial availability makes it highly attractive as a reference photocatalytic film. The photocatalytic and photo-induced superhydrophilitic (PSH) properties of Activ(TM) are studied in some detail and the results reported. Thus, the kinetics of stearic acid destruction (a 104 electron process) are zero order over the stearic acid range 4-129 monolayers and exhibit formal quantum efficiencies (FQE) of 0.7 X 10(-5) and 10.2 x 10(-5) molecules per photon when irradiated with light of 365 +/- 20 and 254 nm, respectively; the latter appears also to be the quantum yield for Activ(TM) at 254 nm. The kinetics of stearic acid destruction exhibit Langmuir-Hinshelwood-like saturation type kinetics as a function of oxygen partial pressure, with no destruction occurring in the absence of oxygen and the rate of destruction appearing the same in air and oxygen atmospheres. Further kinetic work revealed a Langmuir adsorption type constant for oxygen of 0.45 +/- 0.16 kPa(-1) and an activation energy of 19 +/- 1 Kj mol(-1). A study of the PSH properties of Activ(TM) reveals a high water contact angle (67) before ultra-bandgap irradiation reduced to 0degrees after prolonged irradiation. The kinetics of PSH are similar to those reported by others for sol-gel films using a low level of UV light. The kinetics of contact angle recovery in the dark appear monophasic and different to the biphasic kinetics reported recently by others for sol-gel films [J. Phys. Chem. B 107 (2003) 1028]. Overall, Activ(TM) appears a very suitable reference material for semiconductor film photocatalysis. (C) 2003 Elsevier Science B.V All rights reserved.

The alteration of the structural properties and photocatalytic activity of TiO2 following exposure to non-linear irradiation sources

When TiO2 powder was irradiated with a laser light (>0.8 MW peak pulse power (PPP) at 355 nm) a visible change in its colour from white to dark blue was observed. The initial rate of change of the total colour difference was related to the laser light intensity and the longer the irradiation time the more substantial the colour change. The result of X-ray diffraction (XRD) studies showed that the crystal structure of the TiO2 developed a more rutile form after laser exposure. ESR studies indicated that the colour change was associated with the generation of Ti(III) species in the photocatalyst. Electron microscopic studies showed that more spherical shaped particles of TiO2 were observed after laser treatment although the average particle size remained largely unchanged. No significant changes in the band gap or the surface area of the laser modified TiO2 were observed. The laser modified photocatalyst showed no enhancement in activity for the destruction of methylene blue, rhodamine B and stearic acids, indicating that the rutile/anatase ratio is unimportant in the destruction of the test pollutants used in this work, via TiO2 photocatalysis

Preparation and characterisation of novel thick sol-gel titania film photocatalysts

The preparation and characterization of thick (9 mum), clear, mechanically robust and photocatalytically active films of nanocrystalline anatase titania are described. XRD and SEM analysis show the films comprise 13 nm particles of anatase TiO2. Thin (54 nm) films of the 'paste' TiO2, along with sol-gel titania films made by a more traditional route are also prepared and characterised. All titania films mediate the photocatalytic destruction of stearic acid with a quantum yield of 0.0016 +/- 0.0003. using either 365 nm (i.e. BLB) or 254 nm (germicidal) light. P25 TiO2 films also appear to mediate the same process with a similar formal quantum efficiency. Of all the films tested, the thick paste TiO2 films are the most ideally suited for use with near UV light, for reasons which are discussed. All the titania films tested exhibit photoinduced superhydrophilicity.

Titania and tungsten doped titania thin films on glass; active photocatalysts

Acidification of an isopropanol solution containing mixtures of [Ti(OPri)(4)] and [W(OEt)(5)] produced solutions from which various TiO2, WO3 and TiO2/WO3 thin films could be obtained by dip coating and annealing. The films were analysed by X-ray diffraction, SEM/EDAX, Raman, electronic spectra, contact angle and photoactivity with respect to destruction of an over layer of stearic acid. The TiO2/WO3 films were shown to be mixtures of two phases TiO2 and WO3 rather than a solid solution TixWyO2. The 2% tungsten oxide doped titania films were shown to be the most effective photocatalysts. All of the TiO2 and TiO2/WO3 films showed light induced superhydrophillicity. (C) 2002 Elsevier Science Ltd. All rights reserved.

Anatase thin films on glass from the chemical vapor deposition of titanium(IV) chloride and ethyl acetate

Thin (50-500 nm) films of TiO2 may be deposited on glass substrates by the atmospheric pressure chemical vapor deposition (APCVD) reaction of TiCl4 with ethyl acetate at 400600 C. The TiO2 films are exclusively in the form of anatase, as established by Raman microscopy and glancing angle X-ray diffraction. X-ray photoelectron spectroscopy gave a 1:2 Ti:O ratio with Ti 2P(3/2) at 458.6 eV and O 1s is at 530.6 eV. The water droplet contact angle drops from 60degrees to

Atmospheric pressure chemical vapour deposition of titanium dioxide coatings on glass

Atmospheric pressure chemical vapour deposition of titanium dioxide coatings on glass substrates was achieved by the reaction of TiCl4 and a co-oxygen source (MeOH, EtOH, (PrOH)-Pr-i or H2O) at 500-650degreesC. The coatings show excellent uniformity, surface coverage and adherence. Growth rates were of the order of 0.3 mum min(-1) at 500degreesC. All films are crystalline and single phase with XRD showing the anatase TiO2 diffraction pattern; a = 3.78(1), c = 9.51(1) Angstrom. Optically, the films show minimal reflectivity from 300-1600 nm and 50-80% total transmission from 300-800 nm. Contact angles are in the range 20-40degrees for as-prepared films and 1-10degrees after 30 min irradiation at 254 nm. All of the films show significant photocatalyic activity as regards the destruction of an overlayer of stearic acid.

Novel TiO2 CVD films for semiconductor photocatalysis

A novel CVD film of titanium(IV) oxide has been prepared on glass, via the reaction of titanium(IV) chloride and ethyl acetate, using a CVD technique. The film is clear, very robust mechanically and comprised of a thin (24 nm) layer of nanocrystalline anatase titania that absorbs light of lambda

Confirmatory method for the determination of various acetylgestagens in animal kidney fat using liquid chromatography-tandem mass spectrometry

A confirmatory method has been developed and validated that allows for the simultaneous detection of medroxyprogesterone acetate (MPA), megestrol acetate (MGA), melengestrol acetate (MLA), chlormadinone acetate (CMA) and delmadinone acetate (DMA) in animal kidney fat using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The compounds were extracted from kidney fat using acetonitrile, defatted using a hexane wash and subsequent saponification. Extracts were then purified on Isolute CN solid-phase extraction cartridges and analysed by LC-MS/MS. The method was validated in animal kidney fat in accordance with the criteria defined in Commission Decision 2002/657/EC. The decision limit (CC) was calculated to be 0.12, 0.48, 0.40, 0.63 and 0.54 g kg-1, respectively, for MPA, MGA, MLA, DMA and CMA, with respective detection capability (CC) values of 0.20, 0.81, 0.68, 1.07 and 0.92 g kg-1. The measurement uncertainty of the method was estimated at 16, 16, 19, 27 and 26% for MPA, MGA, MLA, DMA and CMA, respectively. Fortifying kidney fat samples (n = 18) in three separate assays showed the accuracy of the method to be between 98 and 100%. The precision of the method, expressed as % RSD, for within-laboratory reproducibility at three levels of fortification (1, 1.5 and 2 g kg-1 for MPA, 5, 7.5 and 10 g kg-1 for MGA, MLA, DMA and CMA) was less than 5% for all analytes.

Elimination kinetic of 17 beta-estradiol 3-benzoate and 17 beta-nandrolone laureate ester metabolites in calves' urine

Efficient control of the illegal use of anabolic steroids must both take into account metabolic patterns and associated kinetics of elimination; in this context, an extensive animal experiment involving 24 calves and consisting of three administrations of 17 beta-estradiol 3-benzoate and 17 beta-nandrolone laureate esters was carried out over 50 days. Urine samples were regularly collected during the experiment from all treated and non-treated calves. For sample preparation, a single step high throughput protocol based on 96-well C-18 SPE was developed and validated according to the European Decision 2002/657/EC requirements. Decision limits (CC alpha) for steroids were below 0.1 mu g L-1, except for 19-norandrosterone (CC alpha = 0.7 mu g L-1) and estrone (CC alpha = 0.3 mu g L-1). Kinetics of elimination of the administered 17 beta-estradiol 3-benzoate and 17 beta-nandrolone laureate were established by monitoring 17 beta-estradiol, 17 alpha-estradiol, estrone and 17 beta-nandrolone, 17 alpha-nandrolone, 19-noretiocholanolone, 19-norandrostenedione, respectively. All animals demonstrated homogeneous patterns of elimination both from a qualitative (metabolite profile) and quantitative point of view (elimination kinetics in urine). Most abundant metabolites were 17 alpha-estradiol and 17 alpha-nandrolone (> 20 and 2 mg L-1, respectively after 17 beta-estradiol 3-benzoate and 17 beta-nandrolone laureate administration) whereas 17 beta-estradiol, estrone, 17 beta-nandrolone, 19-noretiocholanolone and 19-norandrostenedione were found as secondary metabolites at concentration values up to the mu g L-1 level. No significant difference was observed between male and female animals. The effect of several consecutive injections on elimination profiles was studied and revealed a tendency toward a decrease in the biotransformation of administered steroid 17 beta form. (c) 2008 Elsevier Ltd. All rights reserved.

The identification of potential alternative biomarkers of nitrofurazone abuse in animal derived food products

Semicarbazide (SEM) was considered to be a characteristic protein-bound side-chain metabolite of the banned veterinary drug nitrofurazone and used as a marker of nitrofurazone abuse. It was recently discovered that SEM can arise in food from sources other than nitrofurazone. This uncertainty over the source of SEM may be overcome if alternative markers specific to tissue-bound nitrofurazone residues can be determined. The structure of nitrofurazone metabolites in vivo and particular proteins to which they are bound are not known. These proteins with altered structure due to the presence of the drug metabolites can be considered as potential alternative biomarkers of nitrofurazone abuse. The proteins implicated in the in vivo binding of nitrofurazone were separated and identified. A crude mixture of proteins extracted from the liver of a rat treated with the drug was separated using a series of different techniques such as preparative isoelectric focusing and size exclusion HPLC. Multiple fractions were assayed by LC-MS/MS to detect the presence of SEM. The proteins containing SEM residues were identified by peptide mass mapping using trypsin digestion and MALDI-TOF. The first protein identified as containing high concentration of SEM was albumin. It was also shown that low molecular weight species within a protein mixture whose main constituent was glutathione S-transferase contained a high concentration of SEM. The chemical composition of these components is under investigation. Preliminary data suggest the SEM forms part of a nitrofurazone metabolite conjugated to glutathione. (C) 2008 Elsevier Ltd. All rights reserved.

Enzyme immunoassay for semicarbazide - The nitrofuran metabolite and food contaminant

Semicarbazide (SEM), the marker residue for the banned nitrofuran veterinary antibiotic nitrofurazone (NFZ), has been detected regularly in foods (47% of recent nitrofuran EU Rapid Alerts involve SEM). However, the validity of SEM as a definitive marker for NFZ has been undermined by SEM arising from other sources including azodicarbonamide, a plastics blowing agent and flour treatment additive. An inexpensive screening test for SEM in food matrices is needed-all SEM testing currently uses expensive LC-MS/MS instrumentation. We now report the first production of antibodies against derivatised SEM. A novel carboxyphenyl SEM derivative was used to raise a polyclonal antibody that has been incorporated into a semi-quantitative microtitre plate ELISA, validated according to the criteria set out in Commission Decision 2002/657/EC, for use with chicken muscle. The antibody is highly specific for derivatised SEM, cross-reactivity being 1.7% with NFZ and negligible with a wide range of other nitrofurans and poultry drugs. Samples are derivatised with o-nitrobenzaldehyde and simultaneously protease digested before extraction by cation exchange SPE. The ELISA has a SEM detection capability (CC beta) of 0.25 mu g kg(-1) when a threshold of 0.21 mu g kg(-1) is applied to the selection of samples for confirmation (lowest observed 0.25 mu g kg(-1) fortified sample, n = 20), thus satisfying the EU nitrofurans' minimum required performance limit of 1 mu g kg(-1). N-FZ-incurred muscles (12) containing SEM at 0.5-5.0 mu g kg(-1) by LC-MS/MS, all screened positive by this ELISA protocol which is also applicable to egg and chicken liver. (C) 2007 Elsevier BN. All rights reserved.