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Trace inorganic impurities in active pharmaceutical ingredients (APIs) while having limited toxicological significance might affect the down stream processing properties of those substances. The level of impurities in paracetamol batches was quantified and mapped using inductively coupled polarization mass spectrometry (ICP-MS) and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX). The physical form of samples was assessed using X-ray powder diffraction (XRPD) and characterised thermally using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Surface properties were evaluated using inverse gas chromatography (IGC) and moisture sorption. Size distribution was measured using an aerosizer with dry powder dispersion. Physical analysis confirmed that the batches were of the same physical form and particle size distribution was shown to be similar. The SEM-EDX analysis however revealed the presence of aluminium on the surface of particles. This was supported by ICP-MS analysis, which showed different levels of aluminium between batches ranging from 0.1 to 5.6 ppm. IGC indicated that the batches with the highest aluminium content had the highest dispersive free energy. Differences in levels of inorganic impurities typically not considered significant in drug substance specifications correspond with differences in physical properties of APIs, with potential downstream consequences for processing and finished product performance.
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PMID:The impact of low-level inorganic impurities on key physicochemical properties of paracetamol. 1788 12

Twelve camphor (cinnamomum camphora) tree bark samples were collected from Hiroshima and Kyoto, and the matrix element composition and morphology of the outer surface of these camphor tree bark samples were studied by EDXS and SEM respectively. After a dry decomposition, DOWEX 1-X8 anion exchange resin was used to separate uranium from matrix elements in these camphor tree bark samples. Finally, 235U/238 U isotope ratios in purified uranium solutions were determined by MC-ICP-MS. It was demonstrated that the outer surface of these camphor tree bark samples is porous and rough, with Al, Ca, Fe, K, Mg, Si, C, O and S as its matrix element composition. Uranium in these camphor tree bark samples can be efficiently separated and quantitatively recovered from the matrix element composition. Compared with those collected from Kyoto, the camphor tree bark samples collected from Hiroshima have significantly higher uranium contents, which may be due to the increased aerosol mass concentration during the city reconstruction. Moreover, the 235 U/23.U isotope ratios in a few camphor tree bark samples collected from Hiroshima are slightly higher than 0.007 25.
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PMID:[Determination of 235U/238U isotope ratios in camphor tree bark samples by MC-ICP-MS after separation of uranium from matrix elements]. 1794 30

The E.U. Directive on incineration of waste regulates the harmful emissions of particles and twelve toxic elements, including copper, chromium, and arsenic. More information is critically needed on the speciation and behavior of these trace elements during combustion, including the effects of different process variables, as well as of different fuels and fuel mixtures. Using a 15 kW pellets-fueled grate burner, experiments were performed to determine the fate of copper, chromium, and arsenic during combustion of chromate copper arsenate (CCA) preservative wood. The effects of co-combustion of CCA-wood with peat were also studied since peat fuels previously have proved to generally reduce ash related problems. The fate and speciation of copper, chromium, and arsenic were determined from analysis of the flue gas particles and the bottom ash using SEM-EDS, XRD, XPS, and ICP-AES. In addition, chemical equilibrium model calculations were performed to interpret the experimental findings. The results revealed that about 5% copper, 15% chromium, and 60% arsenic were volatilized during combustion of pure CCA-wood, which is lower than predicted volatilization from the individual arsenic, chromium, and copper oxides. This is explained by the formation of more stable refractory complex oxide phases for which the stability trends and patterns are presented. When co-combusted with peat, an additional stabilization of these phases was obtained and thus a small but noteworthy decrease in volatilization of all three elements was observed. The major identified phases for all fuels were CuCrO2(s), (Fe, Mg, Cu)(Cr, Fe, Al)04(s), Cr2O3(s), and Ca3(AsO4)2(s). Arsenic was also identified in the fine particles as KH2AsO4(s) and As2O3(s). A strong indication of hexavalent chromium in the form of K2CrO4 or as a solid solution between K3Na(CrO4)2 and K3Na(SO4)2 was found in the fine particles. Good qualitative agreement was observed between experimental data and chemical equilibrium model calculations.
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PMID:Fate of Cu, Cr, and As during combustion of impregnated wood with and without peat additive. 1794 5

In this work, a novel sol-gel coating of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS)-silica was prepared for capillary microextraction (CME) of trace Cu, Zn, Ni, Hg and Cd followed by on-line ICP-MS detection. This organic-inorganic hybrid coating was in situ created on the inner walls of fused silica capillary using a sol solution containing tetramethoxysilane (TMOS) as a precursor, AAPTS as a co-precursor, ethanol as the solvent and cetyltrimethylammonium bromide (CTAB) as the template. The structure of the capillary coating was characterized by IR, SEM and TEM. Various experimental parameters affecting capillary microextraction of the target analytes have been investigated carefully, and the optimized extraction conditions were established. It was found that the AAPTS-silica coating with a terminal functional group of -NH-CH2-CH2-NH2 exhibited a high selectivity towards the selected metal ions. With a consumption of 1.0 mL sample solution and 80 microL eluent, the detection limits (3sigma) were found to be 1.8, 11.8, 1.1, 3.3 and 1.4 pg mL(-1) for Cu, Zn, Ni, Hg and Cd, respectively. A sampling frequency of 14 h(-1) and an enrichment factor of 12.5 were obtained under the optimized experimental conditions. The relative standard deviations (RSDs) for the target analytes were less than 3.6% (C = 1 ng mL(-1), n = 7, sample volume = 1 mL). Two certified reference materials of NIES No.10-c rice flour and BCR-CRM 278 mussel flesh were analyzed to validate the proposed method, and the determined values were in good agreement with the certified values. The developed method had also been applied to the determination of trace target elements in human hair, serum and urine, and the recoveries for the spiked samples were in the range of 89.2-101.8%. The AAPTS-silica coated capillary showed an excellent pH resistance and could be used for more than 120 times without decreasing adsorption efficiency.
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PMID:Preparation of a high pH-resistant AAPTS-silica coating and its application to capillary microextraction (CME) of Cu, Zn, Ni, Hg and Cd from biological samples followed by on-line ICP-MS detection. 1802 4

To realize the simultaneous removal and recovery of phosphate and partial nitrogen from stale human urine, a series of lab-scale jar tests, adopting MgCl2 x 6H2O as precipitant, were conducted to study the influence of the molar ratio of Mg/PO4(3-)-P, pH, mixing speed, reaction time and precipitation time on MAP precipitation. The experiment results showed that the molar ratio of Mg/PO4(3-)-P was found to be a very important operating parameter to affect phosphorus recovery efficiency. When the molar ratio of Mg/PO4(3-)-P was above 1.3:1, the phosphorus recovery efficiency was above 95% and the residual phosphorous was less than 10 mg/L in the solution. Increasing pH with 10 mol/L NaOH solution could not increase the recovery phosphorus efficiency obviously. Without pH control, the optimal parameters of reaction time, precipitation time and mixing speed could be set at 20 min, 2.0 h and 120 r/min, respectively. To reveal the chemical characteristics of MAP products from human urine, three MAP product samples, with no pH adjustment and under the above optimal operation condition, were obtained at different Mg/PO4(3-)-P molar ratios of 1:1, 1.3:1 and 1.5:1, respectively, and analyzed with SEM, XRD and ICP instrumentation. These precipitates were identified as nearly pure struvite (12.62% of P, 5.71% of N and 9.91% of Mg) with the presence of trace calcium, potassium and sodium. The contents of phosphorus, nitrogen and magnesium in the precipitates were 13.54%, 5.34% and 9.01% (Mg/PO4(3-)-P = 1:1), 13.78%, 5.23% and 9.36% (Mg/PO4(3-)-P = 1.3:1), as well as 13.34%, 5.12% and 9.15% (Mg/PO4(3-)-P = 1.5:1), respectively.
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PMID:[Phosphorus removal and recovery from human urine with MAP crystallization]. 1826 83

Titanium and its alloys, the most commonly used materials for dental and orthopaedic implants are generally coated with bioactive materials such as sol-gel derived titania, silica and calcium phosphate in order to render these materials bioactive. In the present work a coating containing nanosized titania particles having anatase structure was developed on titanium substrate by thermal decomposition of titanium tetrachloride in isopropanol. A modified titania-silica mixed oxide coating was developed by incorporating the required amount of silica in the coating system. The presence of silica at small weight percentage caused improvement of adhesion and corrosion resistance of the coating. In vitro bioactivity tests were performed in 1.5 Kokubo's simulated body fluid after alkaline treatment of the titania/titania-silica coatings and the performance was compared with that of the titania coating developed by simple thermal oxidation. TF-XRD, FTIR and SEM-EDAX were used to investigate the microstructural morphology and crystallinity of the coatings. Elemental analysis of simulated body fluid was carried out using ICP-AES and spectrophotometry. Enhanced biogrowth was facilitated on the titania coating incorporated with low silica content.
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PMID:Development and bio-electrochemical characterization of a novel TiO(2)-SiO (2) mixed oxide coating for titanium implants. 1836 Jul 99

Rapid surface oxidation of a metal was carried out using a low voltage (9-18 V dc) power supply to examine the feasibility of low power electrocorrosion as an alternative to current metal sampling techniques such as acid digestion. Potential was applied between a metal alloy and a cellulose electrode that was made conductive using an aqueous solution (NH4NO3, KCl). Metal ions diffuse into the cellulose as rapid surface oxidation of the metal occurs. The metal ions can then be extracted and analyzed using atomic spectroscopy (e.g. GFAAS). Steel (316L, SRM 663), brass and aluminum alloys were electro-corroded using constant potential. At short intervals (< 2 min) the mass of corroded metal increased linearly with time. Corrosion rates for Cr, Ni, Cu and Mn ranged from 870 to 34 pg s(-1). The mass of metal corroded increased as applied potential/current increased and depends on the surface area of the cellulose-metal contact. Experiments showed that preferential metal corrosion does not occur in steel samples. SEM images show that there is a relatively large area ( approximately 1mm(2)) of homogenous corrosion and that the most damage occurs closest to the edge of filter paper/metal contact. Low power electrocorrosion was used to identify metals in a fork of unknown composition. Multiple techniques (GFAAS, FAAS and SN-ICP-MS) were used for analysis and it was found that Ag and Cu were the primary metals in the alloy, in a ratio of 3:1. Trace amounts of other metals (<1%) were found but not quantified.
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PMID:Low power electrocorrosion for sample preparation: identification of metals in alloys. 1837 6

Double-surface-silvered polyimide films have been successfully fabricated using silver ammonia complex cation ([Ag(NH3)2]+) as the silver precursor and 3,3',4,4'-benzophenonetetracarboxylic dianhydride/4,4'-oxidianile- (BTDA/ODA-) based poly(amic acid) (PAA) as the polyimide precursor via a direct ion-exchange self-metallization technique. The process has been clarified to involve the loading of silver(I) into PAA via ion exchange, the thermally induced reduction of silver(I) to silver(0) and the concomitant imidization of PAA to polyimide upon thermal treatment, the subsequent silver-catalyzed and oxygen-assisted decomposition of the polyimide overlayer, and the self-accelerated aggregation of silver clusters on the film surface to produce well-defined surface silver layers. By employing [Ag(NH3)2]+ solution with a concentration of only 0.01 M and an ion-exchange time of no more than 10 min, the controlled formation of highly reflective and conductive silver surfaces upon thermal treatment at 300 degrees C for less than 4.5 h indicates that the present work provides an efficient route and an effacious silver species for polyimide surface metallization. Although the alkaline characteristics of [Ag(NH3)2]+ have a strong hydrolysis effect on the polyimide precursor chains, the final metallized films retain the key mechanical and thermal properties of the pure polyimide. Films were characterized by ATR-FTIR, XPS, ICP-AES, SEM, TEM, DSC, TGA, reflectivity, conductivity, and mechanical measurements.
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PMID:Controlled formation of optically reflective and electrically conductive silvered surfaces on polyimide film via a direct ion-exchange self-metallization technique using silver ammonia complex cation as the precursor. 1840 10

Purpose of the present work was to study in vitro permeation of gold nanoparticles (NPs) through isolated rat skin and intestine. Another objective was to see the effect of particle size on permeation of the gold NP. Gold NP of 15 nm, 102 nm and 198 nm were synthesized and used for study. Franz diffusion cells were used to evaluate permeation of gold NP from rat skin whereas 'intestinal sac' method was used for assessing intestinal permeation. Number density of gold NP was analyzed by UV-vis spectroscopy whereas amount of gold permeated was measured by ICP mass spectrometry. The absorption and localization of gold NP through rat skin was studied by TEM. Qualitative analysis of gold inside of the rat skin was performed by energy dispersive X-ray spectroscopy (EDS). Gold NP showed negative zeta potential. UV-vis absorption spectra of 15 nm, 102 nm and 198 nm gold NP showed lambda(max) at 520 nm, 535 nm and 577 nm, respectively. SEM study revealed spherical morphology of NP. Gold NP showed size dependent permeation through rat skin and intestine. 15 nm gold NP showed higher permeation compared to 102 nm and 198 nm gold NP. Interestingly, 102 nm and 198 nm gold NP showed lag time of 3h and 6h in case of rat skin only. As the size of the gold NP increased, permeability coefficient and diffusion coefficient was found to be decreased. The permeation of gold NP through intestine was higher than that of skin. TEM study of rat skin revealed accumulation of smaller size gold NP in deeper region of skin whereas larger particles were observed mainly in epidermis and dermis. Presence of gold inside of rat skin was confirmed by EDS. Gold NP would be an interesting carrier for transdermal as well as for oral delivery. The study demonstrated initial proof of concept of percutaneous permeation of smaller size gold particles.
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PMID:In vitro permeation of gold nanoparticles through rat skin and rat intestine: effect of particle size. 1849 8

Postalkoxysilylation with diethoxydimethylsilane has been carried out on the zeolitic lamellar precursors of various topologies such as MWW, FER, CDO and MCM-47 aiming to construct new crystalline structures with expanded pore apertures between the layers. The silylation process and the crystalline and pore structures of the resulting materials have been investigated with the techniques of XRD, IR, (13)C and (29)Si MAS NMR, ICP, SEM, HRTEM, elemental analyses, and N 2 adsorption. In contrast to forming known three-dimensional zeolite structures after direct calcination of the lamellar precursors, the silylation led to new crystalline structures with opener pores, as evidenced by the shift of layer-related diffractions to the lower-angle region in XRD patterns and the enlarged interlayer pores found by HRTEM images. After optimizing the treatment conditions, particularly the amount of silane agent, a maximum and homogeneous silylation was realized, which guaranteed the phase purity in interlayer expanded zeolites. The expanded structures were well preserved after calcination at 823 K or reflux in water for 1 to 2 weeks, indicating a high thermal stability and also a hydrothermal stability. The interlayer expanded zeolites prepared from the metallosilicate precursors of MWW topology exhibited higher catalytic activities in the redox and solid acid-catalyzed reactions of bulky molecules than that of their counterparts with conventional MWW topology.
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PMID:Methodology for synthesizing crystalline metallosilicates with expanded pore windows through molecular alkoxysilylation of zeolitic lamellar precursors. 1852 90


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