Sample Preparation

In this study, we demonstrate the versatility of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOFMS) protein profiling for the species differentiation of a diverse suite of Bacillus spores. MALDI-TOFMS protein profiles of 11 different strains of Bacillus spores, encompassing nine different species, were evaluated. Bacillus species selected for MALDI-TOFMS analysis represented the sporeforming bacterial diversity of typical class 100K clean room spacecraft assembly facilities. A one-step sample treatment and MALDI-TOFMS preparation were used to minimize the sample preparation time. A library of MALDI-TOFMS spectra was created from these nine Bacillus species, the most diverse protein profiling study of the genus reported to date. Linear correlation analysis was used to successfully differentiate the MALDI-TOFMS protein profiles from all strains evaluated in this study. The MALDI-TOFMS protein profiles were compared with 16S rDNA sequences for their bacterial systematics and molecular phylogenetic affiliations. The MALDI-TOFMS profiles were found to be complementary to the 16S rDNA analysis. Proteomic studies of Bacillus subtilis 168 were pursued to identify proteins represented by the biomarker peaks in the MALDI-TOFMS spectrum. Four small, acid-soluble proteins (A, B, C, and D), one DNA binding protein, hypothetical protein ymf J, and four proteins associated with the spore coat and spore coat formation (coat JB, coat F, coat T, and spoIVA) were identified. The ability to visualize higher-molecular-mass coat proteins (10 to 25 kDa) as well as smaller proteins (<10 kDa) with MALDI-TOFMS profiling is critical for the complete and effective species differentiation of the Bacillus genus.

This paper discusses the applicability of small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) techniques for determining the porosity, pore size distribution and internal specific surface area in coals. The method is noninvasive, fast, inexpensive and does not require complex sample preparation. It uses coal grains of about 0.8 mm size mounted in standard pellets as used for petrographic studies.

Radiocarbon dating is the most widely used dating technique in the world. Recent advances in Accelerator Mass Spectrometry (AMS) and sample preparation techniques have reduced the sample-size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes. Today, it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates. The production of 14 C in the atmosphere varies through time due to changes in the Earth's geomagnetic field intensity and in its concentration, which is regulated by the carbon cycle. As a result of these two variables, a radiocarbon age is not equivalent to a calendar age. Four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12,000 calendar years before present. This paper presents high precision paired 230 Th/ 234 U/ 238 U and 14 C age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12,000 to 50,000 years before present. We developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years, taking full account of combined errors in input ages and calibration uncertainties. Our radiocarbon calibration program is publicly accessible at: https://www.radiocarbon.LDEO.columbia.edu/ along with full documentation of the samples, data, and our statistical calibration model.

High-temperature creep tests were conducted on polycrystalline copper of commercial purity in order to investigate the inter-relationship between the extent and the rate of grain boundary sliding (GBS) and the development of internal cavitation. An image processing technique was used to provide quantitative information on the size and shape of the cavities formed over a range of stresses and at temperatures from 673 to 873 K. The results demonstrate that cavity development is inhomogeneous within any specimen, such that there is an increase in the level of cavitation in regions of higher local strain. It is shown by quantitative measurements that the total cavitated area increases at the faster sliding rates, but the number density of cavities decreases at the highest sliding rates because of cavity interlinkage. When interlinkage is taken into account, the results confirm that the overall level of cavitation is related to the occurrence of GBS.

A sensitive, specific and high throughput bioanalytical method using automated sample processing via 96-well plate liquid-liquid extraction and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) has been developed for the determination of methoxsalen in human plasma. Plasma samples with ketoconazole as internal standard (IS) were prepared by employing 0.2 mL human plasma in ethyl acetate:dichloromethane (80:20, v/v). The chromatographic separation was achieved on a Waters Acquity UPLC BEH C18 column using isocratic mobile phase, consisting of 10 mM ammonium formate and acetonitrile (60:40, v/v), at a flow rate of 0.5 mL/min. The linear dynamic range was established over the concentration range 1.1-213.1 ng/mL for methoxsalen. The method was rugged and rapid with a total run time of 1.5 min. It was successfully applied to a pivotal bioequivalence study in 12 healthy human subjects after oral administration of 10 mg extended release methoxsalen formulation under fasting condition.

The functional properties of fats are determined by the distribution pattern of fatty acid residues in their acylglycerols, which may be modified by ester interchange (transesterification). In the margarine industry, the time course of the transesterification of fat blends is monitored by assaying for the amount of the solid fraction at different temperatures (SFC-solid fat content) currently measured by nuclear magnetic resonance (NMR). The aim of this study was to evaluate the feasibility of near infrared spectroscopy (NIRS) to quantify ...

In past, the major reason causing new drug failure was the lack of proper analysis of pharmacokinetic data due to absence of any high advanced techniques but recent years witnessed various advancement in the field of analytical techniques and one of these bioanalysis. Bioanalysis emerges as an important tool during drug discovery and development. This review article focuses on the various methods used during bioanalysis and its application in various fields.

It has been developed a general strategy for the determination of pesticides in agrochemicals by Fourier transform near infrared (FT-NIR) spectroscopy. The methodology is based on previous extraction of the active principles through sonication with acetonitrile and direct determination by transmission measurements, using glass vials as measurement cells and univariate calibration at selected wavenumbers as a function of the pesticide to be analyzed. Chlorsulfuron, metamitron, iprodione, pirimicarb, procymidone and tricyclazole were used as test molecules and data obtained by FT-NIR for 20 samples containing one of these active principles compare well with those found by reference liquid chromatography (HPLC) procedures. In short, FT-NIR provides relative standard deviations between 0.04 and 0.7% and limit of detection values ranging from 0.004 to 0.17 mg g −1 with recovery values between 96.4 and 100.5%. On the other hand, FT-NIR offers a 10 times faster methodology than chromatography ones and an environmentally friendly alternative which reduces the reagent consumption to 1 mL acetonitrile per sample.

This paper is devoted to investigation of morphological and physical-mechanical properties of polyethylene (PE)/clay nanocomposites prepared via in situ polymerization method using bi-supported Ziegler-Natta catalyst. Bentonite type clay and MgCl 2 (ethoxide type) were used as the support of TiCl 4. Catalyst support and polymerization process have been done in slurry phase using Triisobutylaluminum as the cocatalyst. The microstructure of the nanocomposites was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM indicated that almost fully exfoliated PE/clay nanocomposites were produced successfully using this method. According to permeability measurements, it was found that oxygen permeability values of the nanocomposite samples prepared with in situ polymerization method were dropped more than 200% introducing only 1 wt% clay to polymeric matrix. Differential scanning calorimetry (DSC) results indicated that the crystallization temperatures of samples are significantly higher than that of virgin PE. Moderate thermal stability enhancement of in situ polymerized nanocomposites was confirmed using thermogravimetric analysis (TGA).The storage modulus, Young's modulus and tensile strength of prepared samples were increased where the toughness was declined slightly. It seems that good dispersion and exfoliation of clay during polymerization should be responsible to get more effective reinforcing properties for clay in this method comparing to melt blending method for preparation of polyethylene nanocomposites.

Fabrication of microfluidic systems capable of extracting and isolating nucleic acids from biological samples and preparing them for downstream applications within the same device is of interest as on-chip sample preparation reduces the time and effort expended on multi-step benchtop procedures. A microfluidic chip capable of cell lysis, nucleic acid extraction and immobilization has been developed in our laboratory. This report focuses on substrate development and chip integration of the nucleic acid immobilization platform. The immobilization region was initially developed using poly-adenylated mRNA released from normal human lymphoblastoid cells. After immobilization, the mRNA remains functional for amplification by the reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qPCR) gene expression analyses. Detailed surface functionalization, chemical modification, and covalent oligonucleotide immobilization methods are described. Vapor and liquid ...

An at-line analysis protocol is presented that allows the determination of four UV filters, two polycyclic musk compounds and caffeine in water at concentration level of ng L −1 . The fully automated method includes analytes enrichment by Microextraction by packed sorbent (MEPS) coupled directly to large volume injection-gas chromatography-mass spectrometry. Two common SPE phases, C8 and C18, were examined for their suitability to extract the target substances by MEPS. The analytes were extracted from small sample volumes of 800 L with recoveries ranging from 46 to 114% for the C8-sorbent and 65-109% for the C18-sorbent. Limits of detection between 34 and 96 ng L −1 enable the determination of the analytes at common environmental concentration levels. Both sorbents showed linear calibration curves for most of the analytes up to a concentration level of 20 ng mL −1 . Carryover was minimized by washing the sorbents 10 times with 100 L methanol. After this thorough cleaning, the MEPS are re-used and up to 70 analyses can be performed with the same sorbent. The fully automated microextraction GC-MS protocol was evaluated for the influence of matrix substances typical for wastewater. Dilution of samples prior to MEPS is recommended when the polar caffeine is present at high concentration. Real water samples were analyzed by the MEPS-GC-MS method and compared to standard SPE.

... Available online 12 March 2002. Abstract. The present contribution shows the results of tests on geological materials for determination of the rare-earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, as well as Y and Sc. ...

The exoskeleton of the lobster Homarus americanus is a multiphase biological composite material which consists of an organic matrix (crystalline α-chitin fibers and various types of non-crystalline proteins) and minerals (mainly calcite). In this study we discuss experimental data about the mesoscopic structure and the crystallographic texture (orientation distribution) of the α-chitin–protein fiber network in this material. The synchrotron measurements reveal very strong crystallographic textures of the α-chitin. According to these data, a large fraction of the α-chitin lattice cells is arranged with their longest axis parallel to the normal of the surface of the exoskeleton. Additionally, a smaller fraction of the α-chitin cells is oriented with their longest axis perpendicular to the cuticle surface. These structural investigations reveal the pronounced role of crystallographic orientation distributions in mineralized biological composite materials which may be of relevance for an improved understanding of biological and bio-inspired nano-composites.

Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small-pore structure of SiO 2 prepared by the alkoxide method in dierent experimental conditions. Samples prepared in strong acidic environment (pH 2) contain only small pores with mean radius R $ 5 # A, while those prepared at pH 6 and pH 9 contain pores of two sizes, R $ 5 and R $ 17±26 # A. The in¯uence of pH, water/alkoxide molar ratio and temperature of heat-treatment of the samples on their pore structure has been studied. Ó

On-line conversion and determination of aspirin using a flow injection-capillary electrophoresis system A novel, rapid, and simple capillary electrophoresis (CE) method has been developed for the determination of aspirin by on-line treatment with alkali. Such on-line reaction with 0.20 mol/L NaOH solution for 2.5 min at 458C automatically and reproducibly converts aspirin into its hydrolysis product salicylic acid. Analysis is carried out in less than 12 min after conversion of aspirin in a flow injection (FI) system coupled to a CE instrument via a split-flow interface cell, and a sampling frequency of 9 h -1 is achievable. The on-line conversion method has been used to determine aspirin in four commercial pharmaceutical preparations, and the results are satisfactory.

Proper mixing of reagents is of paramount importance for an efficient chemical reaction. While on a large scale there are many good solutions for quantitative mixing of reagents, as of today, efficient and inexpensive fluid mixing in the nanoliter and microliter volume range is still a challenge. Complete, i.e., quantitative mixing is of special importance in any small-scale analytical application because the scarcity of analytes and the low volume of the reagents demand efficient utilization of all available reaction components. In this paper we demonstrate the design and fabrication of a novel centrifugal force-based unit for fast mixing of fluids in the nanoliter to microliter volume range. The device consists of a number of chambers ͑including two loading chambers, one pressure chamber, and one mixing chamber͒ that are connected through a network of microchannels, and is made by bonding a slab of polydimethylsiloxane ͑PDMS͒ to a glass slide. The PDMS slab was cast using a SU-8 master mold fabricated by a two-level photolithography process. This microfluidic mixer exploits centrifugal force and pneumatic pressure to reciprocate the flow of fluid samples in order to minimize the amount of sample and the time of mixing. The process of mixing was monitored by utilizing the planar laser induced fluorescence ͑PLIF͒ technique. A time series of high resolution images of the mixing chamber were analyzed for the spatial distribution of light intensities as the two fluids ͑suspension of red fluorescent particles and water͒ mixed. Histograms of the fluorescent emissions within the mixing chamber during different stages of the mixing process were created to quantify the level of mixing of the mixing fluids. The results suggest that quantitative mixing was achieved in less than 3 min. This device can be employed as a stand alone mixing unit or may be integrated into a disk-based microfluidic system where, in addition to mixing, several other sample preparation steps may be included. Physics 80, 075102-1 075102-2 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-3 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-5 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-6 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒ 075102-7 Noroozi et al. Rev. Sci. Instrum. 80, 075102 ͑2009͒

Ultraviolet matrix-assisted laser desorption/ionization mass spectrometric (UV-MALDI-MS) analysis of highly acidic, thermally labile species such as glycosaminoglycan-derived oligosaccharides is complicated by their poor ionization efficiency and tendency to fragment through the loss of sulfo groups. We have utilized a systematic approach to evaluate the effect of alkali metal counterions on the degree of fragmentation through SO 3 loss from a highly sulfated model compound, sucrose octasulfate (SOS). The lithium, sodium, potassium, rubidium, and cesium salts of SOS were analyzed by UV-MALDI-time-of-flight (TOF)MS using an ionic liquid matrix, bis-1,1,3,3tetramethylguanidinium a-cyano-4-hydroxycinnamate. The positive-ion and negative-ion MALDI mass spectra of five alkali metal salts of SOS were compared in terms of the degree of analyte fragmentation through the SO 3 loss and the absolute intensity of a molecular ion signal. Experimental results demonstrate that the lithium, sodium, and potassium salts of SOS undergo some degree of fragmentation through the loss of SO 3 , whereas the fragmentation through the loss of SO 3 in the rubidium and cesium salts of SOS is suppressed. A high detection sensitivity associated with the stability of sulfate half-esters was achieved for the cesium salt of SOS using positive-ion detection. Finally, the cesium salt of chondroitin sulfate A disaccharide was successfully analyzed using UV-MALDI-TOFMS.

A simple method for the separation and determination of inorganic arsenic (iAs) species in natural and drinking water was developed. Procedures for sample preparation, separation of As(III) and As(V) species and preconcentration of the total iAs on fixed bed columns were defined. Two resins, a strong base anion exchange (SBAE) resin and a hybrid (HY) resin were utilized. The inductively-coupled plasma-mass spectrometry method was applied as the analytical method for the determination of the arsenic concentration in water. The governing factors for the ion exchange/sorption of arsenic on resins in a batch and a fixed bed flow system were analyzed and compared. Acidity of the water, which plays an important role in the control of the ionic or molecular forms of arsenic species, was beneficial for the separation; by adjusting the pH values to less than 8.00, the SBAE resin separated As(V) from As(III) in water by retaining As(V) and allowing As(III) to pass through. The sorption activity of the hydrated iron oxide particles integrated into the HY resin was beneficial for bonding of all iAs species over a wide range of pH values from 5.00 to 11.00. The resin capacities were calculated according to the breakthrough points in a fixed bed flow system. At pH 7.50, the SBAE resin bound more than 370 g g −1 of As(V) while the HY resin bound more than 4150 g g −1 of As(III) and more than 3500 g g −1 of As(V). The high capacities and selectivity of the resins were considered as advantageous for the development and application of two procedures, one for the separation and determination of As(III) (with SBAE) and the other for the preconcentration and determination of the total arsenic (with HY resin). Methods were established through basic analytical procedures (with external standards, certified reference materials and the standard addition method) and by the parallel analysis of some samples using the atomic absorption spectrometry-hydride generation technique. The analytical properties of both procedures were similar: the limit of detection was 0.24 g L −1 , the limit of quantification was 0.80 g L −1 and the relative standard deviations for samples with a content of arsenic from 10.00 to 300.0 g L −1 ranged from 1.1 to 5.8%. The interference effects of anions commonly found in water and some organic species which can be present in water were found to be negligible. Verification with certified reference materials proved that the experimental concentrations found for model solutions and real samples were in agreement with the certified values.

Different methods for the determination of several metals in soils by flame atomic absorption spectrometry (FAAS) were investigated. Different procedures for total dissolution of soil: I -HF+HClO 4 , H 3 BO 3 , HCl digestion (conventional heating), II -HF+HClO 4 , H 3 BO 3 digestion followed by fusion with LiBO 2 (conventional heating) and III -HF+HCl+HNO 3 , H 3 BO 3 digestion (microwave heating), as well as a leaching procedure with HNO 3 +HClO 4 , HCl were tested and compared. For quality assessment, the certified reference material S-1 soil was used. For most of the investigated metals, the best accuracy and precision were achieved when the procedure I or III were used. The developed procedure was applied to the analysis of soil samples from crude oil refinery and dump of petroleum origin wastes regions.

Miniaturised ultrasonic solvent extraction procedure was developed for the determination of selected polychlorinated biphenyls (PCBs) in soil samples by gas chromatography-mass-selective detection by using 2 3 factorial experimental design. Recoveries of PCBs from fortified soil samples are over 90% for three different fortification levels between 40 and 120 g kg −1 , and relative standard deviations of the recoveries are below 7%. The limits of detection (LODs) ranged from 0.003 to 0.006 g kg −1 . The performance of the proposed method was compared to traditional shake flask extraction method on the spiked real soil sample and extraction methods showed comparable efficiencies. Proposed miniaturised ultrasonic solvent extraction offers several advantages, i.e., reducing sample requirement for measurement of target compound, less solvent consumption and reducing the costs associated with solvent purchase and waste disposal.

This study proposes a procedure for determining sodium, potassium, calcium and magnesium in biodiesel samples by flame atomic absorption spectrometry (F AAS). The sample was prepared as a microemulsion without surfactant. The optimized composition of the microemulsion was 10% (w/v) biodiesel, 75% (v/v) n-propanol, 1% (v/v) concentrated nitric acid and 14% (v/v) of aqueous solution formed by 0.2% (v/v) of nitric acid and 0.5% (v/v) of ionization suppressor. Analyte signals in the samples as microemulsion were found to be stable for a period of 15 days. Analytical curves were obtained using organometallic standard solutions. The limits of detection (LOD) found for the proposed procedure were 0.1 µg g − 1 , 0.01 µg g − 1 , 0.04 µg g − 1 , and 0.004 µg g − 1 for Na, K, Ca and Mg, respectively. The reference method established by ABNT (Brazilian Association of Technical Norms) NBR 15556:2008 was used to verify the accuracy of the proposed procedure. No significant statistical difference was found between the results obtained with the proposed and the chosen reference procedure. The proposed procedure showed no matrix influence when recovery tests were performed (89%-103%). The results found in this study show that the proposed procedure is a good alternative for determining Na, K, Ca, and Mg by F AAS in biodiesel samples.

A procedure for the determination of three chloroanisoles (2,4,6-trichloro, 2,3,4,6-tetrachloro and pentachloroanisol), as well as their precursor chlorophenols (2,4,6-trichloro, 2,3,4,6-tetrachloro and pentachlorophenol), involved in the presence of cork taint in red wine has been developed. Samples, up to 1 l, were concentrated using a 200 mg Oasis HLB solid-phase extraction (SPE) cartridge. Chlorophenols were quantitatively eluted from this sorbent with 3 ml of methanol. Chloroanisoles were mainly recovered in a second fraction of n-hexane (2 ml). Both fractions were combined and mixed with an aqueous solution of sodium bicarbonate and 50 l of acetic anhydride. Chlorophenols were acetylated in the aqueous-methanolic phase and extracted to n-hexane. Chloroanisoles remained unaffected in the n-hexane layer. Both groups of compounds were determined by gas chromatography-tandem mass spectrometry in the same chromatographic analysis. Using a temperature programmable vaporization injector detection limits from 0.2 to 2.4 ng l −1 , below their sensorial threshold level in red wine, were obtained for all compounds. Average recoveries higher than 80% and acceptable precision were achieved using red wine samples spiked with the analytes at different concentration levels.

We have analyzed the model organism Caenorhabditis elegans with the help of phase-contrast x-ray tomography. This work combines techniques from x-ray imaging studies of single biological cells by in-line holography with three-dimensional reconstruction and furthermore extends these studies to the multicellular level. To preserve the sub-cellular ultrastructure of the nematodes, we used the near-native sample preparation of high-pressure freezing as commonly used in the field of electron microscopy. For the presented samples, a standard, non-magnifying parallel-beam setting, as well as a magnifying, divergent-beam setting using nanofocusing optics is evaluated based on their tomographic reconstruction potential. In this paper, we address difficulties in sample preparation and issues of image processing. By experimental refinement and through optimized reconstruction procedures, we were able to perform x-ray imaging studies on a living specimen.

Nanoparticles of chromium oxide have been synthesized by following a co-precipitation route at various pH values of the precursor solution. Structural and morphological analysis were carried out by using XRD and TEM techniques which revealed that the size of nanoparticles synthesized at pH 9 was smaller as compared to those synthesized at other pH values. The thick films of synthesized samples were deposited on alumina substrate and their sensing response to methanol, ethanol and isopropanol was investigated at different operating temperatures. It was observed that all the sensors gave optimum response at 250 • C. It has been observed that sample prepared at pH 9, being a collection of smallest particles as compared to other samples, exhibited high sensing response to alcohol vapour. Sensor response of all the samples tested was significantly higher towards isopropanol vapour than towards methanol or ethanol.

Selenium content of soils is an important issue due to the narrow range between the nutritious requirement and toxic effects upon Se exposure. However, its determination is challenging due to low concentrations within complex matrices that hamper the analysis in most spectroscopic techniques. In this study, we explored the possibilities of several analytical approaches combined with total reflection X-ray (TXRF) spectrometry for soil Se determinations. The direct analysis of a solid suspension using 20 mg of fine ground material (<50 µm) has a relatively high Se limit of detection (LOD) of 1 mg/kg (worldwide Se average in soils ) 0.4 mg/kg) and is therefore only suitable for seleniferous soils. Several fast and simple analytical strategies were developed to decrease matrix effects and improve the LOD for Se determination in soil digests. On one hand, the application of a liquid-liquid extraction procedure using ethyl ether and the introduction of a Cr absorbent in the instrument configuration were carried out to avoid the associated problems on TXRF analysis of soil extracts due to the high Fe concentrations (∼700 mg/L). On the other hand, a dispersive liquid-liquid microextraction procedure (DLL-ME) before the TXRF analysis of the soil digest was also developed. The effects of various experimental parameters such as sample volume, effect of major elements present in the soil matrix (Fe), and Se concentration in the sample were investigated. The LOD using this analytical methodology (0.05 mg/kg of Se) was comparable to or lower than those obtained in previous works using other popular spectrometric techniques such as GFAAS, ICPMS, and AFS. The calculated Se concentration for JSAC-0411 ([Se] ) 1.32 ( 0.27 mg/kg) using the combination of DLLME and TXRF ([Se] ) 1.40 ( 0.23 mg/kg) was in agreement with the certified value.

Indium tungsten oxide (In6WO12) powders and thin films were prepared from a 2,4-pentanedione solution containing In(NO3)·xH2O and WCl6. X-ray diffraction results indicated that phase-pure In6WO12 powder formed after drying and heating the solution at 900 °C. Glancing X-ray diffraction results indicated that thin-film samples prepared on fused quartz substrates at 600 and 700 °C contained a disordered fluorite-related phase whereas those prepared at 800 °C contained the ordered compound—In6WO12. Films prepared at 900 °C reacted with the substrate to form In2Si2O7. Despite the chemical and structural similarity of In6WO12 to several indium-containing fluorite-related oxides, including In2O3, In3Sn4O12, and Ga3−xIn5+xSn2O16, the resistivity of the films prepared in this study ranged from 70 to 720 Ω cm, which is several orders of magnitude higher than reported for the related oxides (approx. 10−3 Ω cm). The band gaps of the films prepared at 600 and 700 °C were estimated from optical transmittance measurements to be 4.1 and 3.8 eV, respectively. Films prepared at 700 °C exhibited substantial coloration when exposed to n-butyl lithium whereas those prepared at 800 °C did not.

A method was validated for the multi-residue analysis of 82 pesticides in grapes at ≤25 ng/g level. Berry samples (10 g) mixed with sodium sulphate (10 g) were extracted with ethyl acetate (10 mL); cleaned by dispersive solid phase extraction and the results were obtained by liquid chromatography–tandem mass spectrometry. Reduction in sample size and proportion of ethyl acetate for extraction did not affect accuracy or precision of analysis when compared to the reported methods and was also statistically similar to the QuEChERS technique. The method was rugged (HorRat < 0.5) with <20% measurement uncertainties. Limit of quantification was <10 ng/g with recoveries 70–120% for most pesticides. The method offers cheaper and safer alternative to typical multi-residue analysis methods for grape.

In this paper, we discuss the synthesis of carbon-sulfur composite (a-C:S) films by vapour phase pyrolysis of maleic anhydride and sulfur. Structural changes in the system are analysed by scanning electron microscopy and powder X-ray diffraction. Microhardness test depicts an increase in the value of hardness with an increase in sulfur concentration. Electrical conductivity of composite samples varies with sulfur concentration. Magnetoresistance (MR) measurements show a drastic increase in the value of MR for the samples prepared at < 900°C. Thermal stability of these samples is analysed by thermogravimetric analysis, which depends on the host structure and the amount of intercalated species.

A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of GDC-0152 in human plasma to support clinical development. The method consisted of a solid-phase extraction for sample preparation and LC-MS/MS analysis in the positive ion mode using TurboIonSpray TM for analysis. d 7 -GDC-0152 was used as the internal standard. A linear regression (weighted 1/concentration 2 ) was used to fit calibration curves over the concentration range of 0.02-10.0 ng/mL for GDC-0152. There were no endogenous interference components in the blank human plasma tested. The accuracy at the lower limit of quantitation was 99.3% with a precision (%CV) of 13.9%. For quality control samples at 0.0600, 2.00 and 8.00 ng/mL, the between-run %CV was ≤8.64. Between-run percentage accuracy ranged from 98.2 to 99.6%. GDC-0152 was stable in human plasma for 363 days at À20 C and for 659 days at À70 C storage. GDC-0152 was stable in human plasma at room temperature for up to 25 h and through three freeze-thaw cycles. In whole blood, GDC-0152 was stable for 12 h at 4 C and at ambient temperature. This validated LC-MS/MS method for determination of GDC-0152 was used to support clinical studies.

We present here combined resistivity and micro-Raman spectroscopy measurements for the superconductor EuBa 2 Cu 3 O 6 + x (Eu-123, EuBCO). We found an important dependence of microstructure and critical temperature on preparation temperature. We also show a strong orientation effect and a T c of 93 K in samples prepared at high temperature relative to those prepared at lower temperature, which exhibit lower T c , broad transitions, and no grain orientation. In addition, we show the influence of annealing conditions on superconducting properties by preparing samples with the same oxygen content (x 0.38) but with various T and P(O 2 ). The peculiar behavior of Eu-123 with temperature by considering a different hole injection sequence for Eu-123 with respect to Y-123 is explained. Micro-Raman measurements seem to support this hypothesis.

In this work we present the synthesis, characterisation and the thermoluminescence (TL) response of nanoporous carbon doped aluminium oxide Al 2 O 3 :C produced by anodic oxidation of aluminium in organic and inorganic solvents. The X-ray and scanning electron microscopy (SEM) measurements reveal that the synthesised samples are amorphous and present highly ordered structures with uniform pore distribution with diameter of the order 50 nm. The photoluminescence and spectroscopic analysis in the visible and infrared regions show that the luminescence properties presented by the samples prepared in organic acid are due to carboxylate species, incorporated in anodic alumina films during the synthesis process. After an annealing treatment, part of the incorporated species decomposes and is incorporated into the structure of the aluminium oxide yielding a highly thermoluminescent detector (TL) . The results for X-ray irradiation in the range from 21 to 80 keV indicate a linear TL response with the dose in the range from 5 mGy to 1 Gy, suggesting that nanoporous aluminium oxide produced in the present route of synthesis is a suitable detector for radiation measurements.

Suppressed ion chromatography with a highly selective and high capacity anion-exchange column is used for the determination of anionic compounds in ten commercially available toothpastes. Minimal sample preparation is needed, requiring only dilution and filtration over a solid-phase extraction cartridge. Quantitative analysis of fluoride and monofluorophosphate, as well as chloride, nitrate, orthophosphate, and sulfate is achieved in one chromatographic run with a total analysis time of 25 minutes. Optimized analytical conditions are validated in terms of accuracy, precision, and total uncertainty, and the results demonstrate the reproducibility of ion chromatography. The coefficient of determination for the anions ranges from 0.9896 to 0.9997. The spiked recoveries for the anions are 88-108%. The change in the fluoride content of the toothpaste with storage time is investigated.

Membrane-assisted solvent extraction (MASE) coupled to large volume injection was applied to the determination of (gasoline-type) hydrocarbon contamination in water samples. Hexane was used as acceptor phase. 50 L extract was injected in the programmed temperature vaporizer injector using combined split-splitless evaporation. The extraction conditions were optimized both for MASE with agitation and for MASE with sonication. In the course of optimization the effect of extraction time, extraction temperature, agitation speed, solvent volume, pH, ionic strength and the addition of methanol were tested. Over 75% recovery was accomplished in the range of diesel oil hydrocarbons (n-C 9-n-C 24). The developed method was validated. Linearity, accuracy and precision were tested. The method showed excellent linearity between 1 and 1000 g L −1 for n-alkanes and between 0.05 and 50 mg L −1 for gasoline. The method was tested with comprehensive GC × GC as well and found to be non-discriminative to all major compounds of diesel oil.

Lormetazepam (Loramet | is a benzodiazepine mainly used as an hypnotic to treat insomnia. Lorazepam (Temesta | is used as an anxiolytic, tranquilizer, sedative, and anticonvulsant, and it is the major metabolite of Iormetazepam. In this study, we designed a method to simultaneously detect and quantify these substances in human breast milk. Solid-phase extraction of 2 mL of milk was followed by derivatization with a trimethylsilyl reagent. Separation and detection was performed using gas chromatography coupled to mass spectrometry in the negative chemical ionization mode. Calibration curves were linear in the ranges of 10-200 and 1-20 ng/mt for Iorazepam and Iormetazepam, respectively. Limits of detection were estimated at 0.016 ng/mL for Iormetazepam and 0.100 ng/mL for Iorazepam. Our method was applied to real case samples from a woman receiving both benzodiazepines. Lorazepam concentrations varied from 55.3 to 123.1 ng/mL, and Iormetazepam concentrations varied from 1.7 to 7.3 ng/mL.

Atomic short-range order is commonly observed in CuMn alloys via a diffuse (1 1 2 0) peak in neutron diffraction patterns. There has been speculation for many years on the existence and nature of any corresponding long-range order. A sample of Cu80Mn20 has been irradiated in a high fast-neutron flux to produce a large number of crystal defects at around room temperature and thus facilitate the ordering process. Measurements of the diffuse neutron scattering from this sample demonstrate that long-range order has been induced in the sample, as evidenced by at least five Bragg peaks. This order is not seen in a reference sample prepared in identical fashion except for the irradiation. The Cowley short-range order parameters for both samples are calculated and a candidate structure for the long-range order is proposed.

A highly sensitive and reliable method for the enantioselective analysis of ibuprofen, ketoprofen and naproxen in wastewater and environmental water samples has been developed. These three pharmaceuticals are chiral molecules and the variable presence of their individual (R)- and (S)-enantiomers is of increasing interest for environmental analysis. An indirect method for enantioseparation was achieved by the derivatization of the (R)-

The catalytic performance and the formation of carbon in Fe-BEA and Fe-MFI catalysts prepared by three methods (hydrothermal synthesis, ion-exchange at room temperature with an iron-nitrate solution and ion-exchange at 80 • C with an iron ammonium sulfate solution) are analyzed with the aim to develop catalysts having larger dimensions of the cavities with respect to the MFI structure (such as ZSM-5 and silicalite) and which could be applied in the selective hydroxylation of molecules having larger kinetic diameters than benzene. The results show that, apart from minor differences, Fe-BEA catalysts have comparable catalytic performances in selective benzene hydroxylation to phenol with respect to Fe-MFI catalysts. However, all the Fe-BEA samples show a higher formation of carbon than the corresponding Fe-MFI samples as well as the formation of carbon having a higher degree of condensation. This is connected to the larger cavities in the BEA framework, especially at the intersections of the channels, with respect to the MFI framework. Highly active samples were obtained by ion-exchange at 80 • C with the iron ammonium sulfate solution. The phenol productivity in both Fe-MFI and Fe-BEA samples is about 60-70% higher than that of comparable samples prepared by hydrothermal synthesis.

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h r o m b Fast liquid chromatography-quadrupole linear ion trap-mass spectrometry analysis of polyunsaturated fatty acids and eicosanoids in human plasma ଝ Available online xxx Keywords: Mass spectrometry Fast liquid chromatography Linear ion trap On-line solid-phase extraction Eicosanoids Polyunsaturated fatty acid metabolism a b s t r a c t

This paper describes the application of a previously published multi-mycotoxin method for food and feed matrices based on liquid chromatography/electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS) to the analysis of microbial metabolites in indoor matrices. The range of investigated analytes has been extended by 99 fungal and bacterial metabolites to cover now 186 compounds overall. The method is based on a single extraction step using an acidified acetonitrile/water mixture (which has been determined to be preferable to methanol and ethyl acetate) followed by analysis of the diluted crude extract. The analytical signal of one third of the investigated analytes was reduced by more than 50% due to matrix effects in a spiked extract of house dust, whereas the other investigated materials were less critical in that aspect. For determination of method performance characteristics, a spiked reference material for house dust was chosen as a model sample for an extremely complex matrix. With few exceptions, coefficients of variation of the whole procedure of <10% and limits of detection of <50 µg kg −1 were obtained. The apparent recoveries were below 50% for half of the investigated analytes due to incomplete extraction and/or detection-related matrix effects. The application of the method to 14 samples from damp buildings revealed the presence of 20 different analytes at concentrations of up to 130 mg kg −1 . Most of these compounds have never been identified before in real-world samples, although they are known to be produced by indoor-relevant fungi. This underlines the great value of the described method for the on-site determination of microbial metabolites.

a b s t r a c t A simple, rapid and sensitive ultra performance liquid chromatography tandem mass spectrometry method was developed and fully validated for the quantitative determination of seven amphetamines and metabolites in urine. The method was validated for selectivity, linearity, LOQ, LOD, imprecision, bias, analyte and processed sample stability, matrix effect, recovery, carryover and dilution integrity. A classic liquid-liquid extraction with ethyl acetate was used as sample preparation procedure. The compounds were separated on an Acquity UPLC HSS C 18 column in 6.8 min. The linear dynamic range was established from 25 to 500 ng/mL. The limit of quantification was fixed to the lowest calibrator level and the limit of detection ranged from 0.125 to 2.5 ng/mL. The method presented an excellent intra-and inter-assay imprecision and bias (<10.7%) at each measured concentration of two external quality controls (QC) and three "in house" QC. No matrix effects were observed and good recoveries (>70%) were obtained for all the compounds. No carryover was observed after the analysis of high concentrated samples (8000 ng/mL). The method was subsequently applied to authentic samples.

A powerful method to study carbon nanotubes (CNTs) grown in patterned substrates for potential interconnects applications is transmission electron microscopy (TEM). However, high-quality TEM samples are necessary for such a study. Here, TEM specimen preparation by focused ion beam (FIB) has been used to obtain lamellae of patterned samples containing CNTs grown inside contact holes. A dualcap Pt protection layer and an extensive 5 kV cleaning procedure are applied in order to preserve the CNTs and avoid deterioration during milling. TEM results show that the inner shell structure of the carbon nanotubes has been preserved, which proves that focused ion beam is a useful technique to prepare TEM samples of CNT interconnects.

A dense silica glass was prepared by consolidating a highly dispersed silicic acid powder (particle size o10 nm) with the Spark Plasma Sintering (SPS) technique. The glass was characterized by ellipsometry, transmission electron microscopy (TEM), infrared reflectance and transmittance spectroscopy, as well as by Raman, UV-Vis-NIR and solid-state nuclear magnetic resonance (NMR) spectroscopy. The prototypic sample showed a transmittance of about 63% compared to silica glass in the UV-Vis spectral range. Based on the results of infrared transmittance spectroscopy this lower transparency is due to the comparably high water content, which is about 40 times higher than that in silica glass. 1 H magic-angle spinning (MAS) NMR confirmed an increase in hydroxyl groups in the sample prepared by SPS relative to that of the conventional SiO 2 reference glass. Aside from the comparably high water content, we conclude from the similarity of the IR-reflectance and the 29 Si MAS NMR spectra of the SPS sample and the corresponding spectra of the conventionally prepared silica glass, that the short-and medium-range order is virtually the same in both materials. Raman spectroscopy, however, suggests that the number of three-and four-membered rings is significantly smaller in the SPS sample compared to the conventionally prepared sample. Based on these results we conclude that it is possible to prepare glasses by compacting amorphous powders by the SPS process. The SPS process may therefore enable the preparation of glasses with compositions inaccessible by conventional methods.