Low Mass Samples Research Articles

Feasibility of sulfur determination in diesel oil by inductively coupled plasma optical emission spectrometry after microwave-induced combustion using flame retardant

Diesel oil sample preparation for further sulfur determination in fuels is considered a critical step during the analytical sequence mainly due to the high volatility of this sample. Combustion systems have been a suitable alternative to conventional digestion methods but its applicability for highly volatile matrices like diesel oil is restrict to low sample masses due to the high pressure generated during combustion. In order to overcome this limitation, the possibility of employing glass wool as a flame retardant for microwave induced combustion (MIC) method was investigated in the present work for further sulfur determination by inductively coupled plasma optical emission spectrometry. Using flame retardant it was possible to burn up to 400mg of diesel oil without increasing the pressure in dangerous levels. Nitric acid (2, 4, 7 or 14.4molL−1 HNO3) was evaluated as absorbing solution and no significant difference was observed in sulfur recoveries for solutions. Digestion efficiency was evaluated by means of residual carbon content determination, which presented values always lower than 1% showing the high digestion efficiency. For comparison of results, S was also determined by the ASTM D 5453-12 method and an agreement better than 95% was obtained. The accuracy was better than 97% (analysis of certified reference material), blanks were negligible and the limit of detection was considered as suitable for quality control (2μgg−1).

Electrochemical reduction of TiO2 powders in molten calcium chloride

Electrochemical reduction behaviour of TiO2 powder samples, sintered at 1423K and 1673K and weighing ∼ 1.5g and ∼ 10g, was studied by constant voltage electrolysis at 3.1V at 1173K. Both the samples were found to undergo reduction, but the low-temperature sintered and low-mass samples showed better overall reduction than the high-temperature sintered and high-mass samples. The reduction of the bulk parts of the samples became difficult as the sample size was increased from 1.5g to 10g. The size and location of the TiO2 particles in the powder electrode played an important role in the reduction of the oxide to the metal.

Effects of POSS nanoparticles on glass transition temperatures of ultrathin poly(t‐butyl acrylate) films and bulk blends

ABSTRACTAs a model system, thin films of trisilanolphenyl‐POSS (TPP) and two different number average molar mass (5 and 23 kg mol−1) poly(t‐butyl acrylate) (PtBA) were prepared as blends by Langmuir–Blodgett film deposition. Films were characterized by ellipsometry. For comparison, bulk blends are prepared by solution casting and the samples are characterized via differential scanning calorimetry. The increase in Tg as a function of TPP content for bulk high and low molar mass samples are in the order of ∼10 °C. Whereas bulk Tg shows comparable increases for both molar masses (∼10 °C), the increase in surface Tg for higher molar mass PtBA is greater than for low molar mass (∼22 °C vs. ∼10 °C). Nonetheless, the total enhancement of Tg is complete by the time 20 wt % TPP is added without further benefit at higher nanofiller loads. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 175–182

Quantititative Determination of Lycorine and Galanthamine in Galanthus trojanus and G. cilicicus by HPLC-DAD

Lycorine and galanthamine have various biological activities. A reliable HPLC method coupled with DAD detection was developed and validated for the determination of galanthamine and lycorine in Galanthus trojanus and G. cilicicus. A simple method for the extraction of the alkaloids in low-mass plant samples was employed utilizing columns pre-packed with diatomaceous earth (Extrelut). This method was applied to the aerial parts and bulbs of G. trojanus and G. cilicicus (Amaryllidaceae) collected during the flowering season. The chromatographic separation was performed using an isocratic system with a mobile phase of trifluoroacetic acid-water-acetonitrile (0.01:92.5:7.5) applied at a flow rate of 1 mL min(-1) and using a diode array detector. Validation procedures showed that the method was specific, accurate and precise. The highest amount of lycorine (0.012%) was detected in the bulbs of G. trojanus collected from Can (Canakkale), whereas the aerial parts of this species collected from Bayramiç (Canakkale) was not found to contain this alkaloid. In G. cilicicus samples, lycorine was only determined in the bulbs, giving yields of 0.004%; galanthamine yields were between 0.015-0.016%, but none of the G. trojanus samples contained this latter alkaloid.

Quantitative analysis of lycorine in endemicGalanthus xvalentineinothosubsp.subplicatusby HPLC-DAD

Summary Galanthus xvalentinei (J. Allen) Beck nothosubsp. subplicatus (N. Zeybek) A. P. Davis (Amaryllidaceae) is an endemic hybrid between G. nivalis L. and G. plicatus M. Bieb. subsp. byzantinus (Baker) D. A. Webb. Lycorine, a common alkaloid found in Amaryllidaceae plants, has been shown to display important biological activities. In the present study, a reversed-phase high-performance liquid chromatographic method has been used for the quantitative determination of lycorine in the aerial parts and bulbs of G. xvalentinei nothosubsp. subplicatus. A simple method for the extraction of lycorine in lowmass plant samples was employed utilizing pre-packed columns with diatomaceous earth (Extrelut®). The chromatographic separation was carried out using an isocratic system with a mobile phase of trifluoroacetic acid-water-acetonitrile (0.01:95:5) applied at a flow rate of 1 mL min−1 using diode array dedector. The content of lycorine in the bulbs of G. xvalentinei nothosubsp. subplicatus was found to be 0.0028%, however, it was not detected in the aerial parts of this hybrid.

Improving accuracy and sensitivity of isotope ratio mass spectrometry for δ13C and δ15N values in very low mass samples for ecological studies

A modified procedure for isotope ratio mass spectrometry (IRMS) of 13C/12C and 15N/14N ratios of very low biomass samples yielded reproducible data and enhanced the resolution of the instrument beyond its typical detection limit. The main modification was to rely only on oxygen from the chromium oxide catalyst allowing greater precision of measurement. Our method was accurate to weights of 8 μg C and 2 μg N with reference standards and test materials. The collembolan could be measured accurately enough for differences between individuals to be detectable. Attaining this level of resolution with ecological samples makes it feasible to use IRMS while retaining sample mass small enough to be functionally useful in studies of micro-organism food webs.

Immobilization of Poly(1,1-dimethysilacyclobutane) by Means of Anionic Ring-Opening Polymerization on Organic Nanoparticles and Reinvestigation of Crystallization

In the present study, the synthesis of poly(1,1-dimethylsilacyclobutane) (PDMSB) by anionic ring opening polymerization (ROP) is reinvestigated, leading to narrowly distributed molar masses (polydispersities 1.04–1.15) in the range of 2.3 to 60 kg mol−1. Investigations of thermal behavior for low molar mass PDMSB revealed an untypical multiple peaks melting phenomenon, which at first glance, seems to be of the same origin as low molar mass poly(ethylene oxide)s. Small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) measurements are done, proving the fast crystallization and subsequent recrystallization for investigated low molar mass samples. Synthetic attempts are expanded to the surface-initiated anionic ROP of 1,1-dimethylsilacyclobutane (DMSB) monomer from the surface of cross-linked polystyrene (PS) nanoparticles. Novel polycarbosilanes (PCS)/organic core/shell particles are obtained, which are investigated by using transmission electron microscopy (TEM) and dynamic light scattering (DLS) experiments. First insights into the crystallization behavior of surface-attached PDMSB chains reveal that crystallization seems to be hindered.

Kinetic Behavior of Torrefied Biomass in an Oxidative Environment

The combustion of four torrefied wood samples and their feedstocks (birch and spruce) was studied at slow heating programs, under well-defined conditions by thermogravimetry (TGA). Particularly low sample masses were employed to avoid the self-heating of the samples because of the huge reaction heat of the combustion. Linear, modulated, and constant reaction rate (CRR) temperature programs were employed in the TGA experiments in gas flows of 5 and 20% O2. In this way, the kinetics was based on a wide range of experimental conditions. The ratio of the highest and lowest peak maxima was around 50 in the experiments used for the kinetic evaluation. A recent kinetic model by Várhegyi et al. (Várhegyi, G.; Sebestyén, Z.; Czégény, Z.; Lezsovits, F.; Könczöl, S.Energy Fuels 2012, 26, 1323−1335) was employed with modifications. This model consists of two devolatilization reactions and a successive char burnoff reaction. The cellulose decomposition in the presence of oxygen has a self-accelerating (autocatalytic) kinetics. The decomposition of the non-cellulosic parts of the biomass was described by a distributed activation model. The char burnoff was approximated by power-law (n-order) kinetics. Each of these reactions has its own dependence upon the oxygen concentration that was expressed by power-law kinetics too. The complexity of the applied model reflects the complexity of the studied materials. The model contained 15 unknown parameters for a given biomass. Part of these parameters could be assumed common for the six samples without a substantial worsening of the fit quality. This approach increased the average experimental information for an unknown parameter by a factor of 2 and revealed the similarities in the behavior of the different samples.

A Novel Device for Measuring Respirable Dustiness Using Low-Mass Powder Samples

Respirable dustiness represents the tendency of a powder to generate respirable airborne dust during handling and therefore indicates the propensity for a powder to become an inhalation hazard. The dustiness of 14 powders, including 10 different nanopowders, was evaluated with the use of a novel low-mass dustiness tester designed to minimize the use of the test powder. The aerosol created from 15-mg powder samples falling down a tube were measured with an aerodynamic particle sizer (APS). Particle counts integrated throughout the pulse of aerosol created by the falling powder were used to calculate a respirable dustiness mass fraction (D, mg/kg). An amorphous silicon dioxide nanopowder produced a respirable D of 121.4 mg/kg, which was significantly higher than all other powders (p < 0.001). Many nanopowders produced D values that were not significantly different from large-particle powders, such as Arizona Road Dust and bentonite clay. In general, fibrous nanopowders and powders with primary particles >100 nm are not as dusty as those containing granular, nano-sized primary particles. The method used here, incorporating an APS, represents a deviation from a standard method but resulted in dustiness values comparable to other standard methods.

Simultaneous determination of mercury and butyltin species using a multiple species-specific isotope dilution methodology on the European, Anguilla anguilla glass eel and yellow eel

A methodology to simultaneously determine mercury (MeHg, IHg) and butyltin (TBT, DBT, MBT) compounds in eel samples was assessed and validated using multiple isotopically enriched species. The developed methodology was able to analyse simultaneously the organometal species accurately and precisely and to correct for the potential transformations/degradations of the different species during the various steps of the analytical procedure. Low detection limits were achieved (0.007–0.17 µg Hg kg−1 for mercury (Hg) species and 0.42–0.71 µg Sn kg−1 for tin (Sn) species) allowing analysis of low-mass samples and thus the analysis at the individual organism scale, including glass eels for which samples dry weight ranged from 60 to 100 mg. The methodology was validated with certified reference materials (BCR-464, BCR-477, BCR-710, DOLT-4 and NIST-2977) and applied to the analysis of these pollutants in two developmental stages of the European eel, Anguilla anguilla: individual whole glass eels and muscle tissue from yellow eels. The Adour estuary (South-west France) was selected to monitor the bioaccumulation of organometal species in these organisms, according their developmental stage, their morphological parameters and the sampling site. The results suggest that the accumulation of methylmercury in glass eel tissue is related to weight, with higher concentrations in smaller individuals. Butyltin concentrations were very close to the limit of detection, and no significant differences were detected between glass and yellow eels.

Preparation of high-quality next-generation sequencing libraries from picogram quantities of target DNA

New sequencing technologies can address diverse biomedical questions but are limited by a minimum required DNA input of typically 1 μg. We describe how sequencing libraries can be reproducibly created from 20 pg of input DNA using a modified transpososome-mediated fragmentation technique. Resulting libraries incorporate in-line bar-coding, which facilitates sample multiplexes that can be sequenced using Illumina platforms with the manufacturer's sequencing primer. We demonstrate this technique by providing deep coverage sequence of the Escherichia coli K-12 genome that shows equivalent target coverage to a 1-μg input library prepared using standard Illumina methods. Reducing template quantity does, however, increase the proportion of duplicate reads and enriches coverage in low-GC regions. This finding was confirmed with exhaustive resequencing of a mouse library constructed from 20 pg of gDNA input (about seven haploid genomes) resulting in ∼0.4-fold statistical coverage of uniquely mapped fragments. This implies that a near-complete coverage of the mouse genome is obtainable with this approach using 20 genomes as input. Application of this new method now allows genomic studies from low mass samples and routine preparation of sequencing libraries from enrichment procedures.

THE MASS DISTRIBUTION OF STELLAR-MASS BLACK HOLES

We perform a Bayesian analysis of the mass distribution of stellar-mass black holes using the observed masses of 15 low-mass X-ray binary systems undergoing Roche lobe overflow and five high-mass, wind-fed X-ray binary systems. Using Markov Chain Monte Carlo calculations, we model the mass distribution both parametrically---as a power law, exponential, gaussian, combination of two gaussians, or log-normal distribution---and non-parametrically---as histograms with varying numbers of bins. We provide confidence bounds on the shape of the mass distribution in the context of each model and compare the models with each other by calculating their relative Bayesian evidence as supported by the measurements, taking into account the number of degrees of freedom of each model. The mass distribution of the low-mass systems is best fit by a power-law, while the distribution of the combined sample is best fit by the exponential model. We examine the existence of a "gap" between the most massive neutron stars and the least massive black holes by considering the value, M_1%, of the 1% quantile from each black hole mass distribution as the lower bound of black hole masses. The best model (the power law) fitted to the low-mass systems has a distribution of lower-bounds with M_1% > 4.3 Msun with 90% confidence, while the best model (the exponential) fitted to all 20 systems has M_1% > 4.5 Msun with 90% confidence. We conclude that our sample of black hole masses provides strong evidence of a gap between the maximum neutron star mass and the lower bound on black hole masses. Our results on the low-mass sample are in qualitative agreement with those of Ozel, et al (2010).

THESPITZERICE LEGACY: ICE EVOLUTION FROM CORES TO PROTOSTARS

Ices regulate much of the chemistry during star formation and account for up to 80% of the available oxygen and carbon. In this paper, we use the Spitzer c2d ice survey, complimented with data sets on ices in cloud cores and high-mass protostars, to determine standard ice abundances and to present a coherent picture of the evolution of ices during low- and high-mass star formation. The median ice composition H2O:CO:CO2:CH3OH:NH3:CH4:XCN is 100:29:29:3:5:5:0.3 and 100:13:13:4:5:2:0.6 toward low- and high-mass protostars, respectively, and 100:31:38:4:-:-:- in cloud cores. In the low-mass sample, the ice abundances with respect to H2O of CH4, NH3, and the component of CO2 mixed with H2O typically vary by <25%, indicative of co-formation with H2O. In contrast, some CO and CO2 ice components, XCN and CH3OH vary by factors 2-10 between the lower and upper quartile. The XCN band correlates with CO, consistent with its OCN- identification. The origin(s) of the different levels of ice abundance variations are constrained by comparing ice inventories toward different types of protostars and background stars, through ice mapping, analysis of cloud-to-cloud variations, and ice (anti-)correlations. Based on the analysis, the first ice formation phase is driven by hydrogenation of atoms, which results in a H2O-dominated ice. At later prestellar times, CO freezes out and variations in CO freeze-out levels and the subsequent CO-based chemistry can explain most of the observed ice abundance variations. The last important ice evolution stage is thermal and UV processing around protostars, resulting in CO desorption, ice segregation and formation of complex organic molecules. The distribution of cometary ice abundances are consistent with with the idea that most cometary ices have a protostellar origin.

Neutron Capture Measuremetns on Minor Actinides at the n_TOF Facility at CERN: Past, Present and Future

The successful development of advanced nuclear systems for sustainable energy production and nuclear waste management depends on high quality nuclear data libraries. Recent sensitivity stud- ies and reports [1-3] have identi ed the need for substantially improving the accuracy of neutron cross-section data for minor actinides. The n TOF collaboration has initiated an ambitious exper- imental program for the measurement of neutron capture cross sections of minor actinides. Two experimental setups have been constructed for this purpose: a Total Absorption Calorimeter (TAC) [4] for measuring neutron capture cross-sections of low-mass and/or radioactive samples and a set of two low neutron sensitivity C6D6 detectors for the less radioactive materials.

Improved Neutron Capture Cross Section Measurements with the n_TOF Total Absorption Calorimeter

The n TOF collaboration operates a Total Absorption Calorimeter (TAC) [1] for measuring neu- tron capture cross-sections of low-mass and/or radioactive samples. The results obtained with the TAC have led to a substantial improvement of the capture cross sections of 237Np and 240Pu [2]. The experience acquired during the rst measurements has allowed us to optimize the performance of the TAC and to improve the capture signal to background ratio, thus opening the way to more complex and demanding measurements on rare radioactive materials. The new design has been reached by a series of detailed Monte Carlo simulations of complete experiments and dedicated test measurements. The new capture setup will be presented and the main achievements highlighted.

Construction of the state diagram of polymer blend thin films using differential AC chip calorimetry

The phase separation behavior of polymer blend thin films of 100–150 nm was studied using differential AC Chip calorimetry. By taking advantage of the low sensor and sample mass inherent to chip calorimetry, a new methodology based on temperature jumps was developed. This methodology allowed the construction of the state diagram of polymer blend thin films as evidenced for two model systems (PVME/PS and PVME/Phenoxy) displaying a lower critical solution temperature behavior.The state diagram in thin films was compared to the one obtained in bulk using Modulated Temperature DSC. In comparison with bulk, a lower phase separation temperature and a broadening of the homogeneous glass transition temperatures is observed for both model systems. This might be an indication of a surface induced ‘destabilization’ by composition gradients which are not present in bulk.

Quantitative Determination of Galanthamine and Lycorine in an endemic Galanthus species: G. cilicicus

Galanthus cilicicus Baker, an endemic species of the genus Galanthus L. (Amaryllidaceae), is distributed in southern Turkey mainly in the province of Içel [1]. Galanthamine, the most important alkaloid found in Amaryllidaceae species, is used for the treatment of Alzheimer's disease [2]. Lycorine, another important and also a widespread alkaloid found in Amaryllidaceae plants has been proven to have several biological activities [3,4]. A reversed-phase high-performance liquid chromatographic method has been used and validated for the determination of lycorine and galanthamine in G. cilicicus. The extraction of both alkaloids in low-mass plant samples, were carried out by a simple and a rapid method utilizing pre-packed columns with diatomaceous earth (Extrelut®) [5]. The chromatographic separation was performed using an isocratic system with a mobil phase of trifluoroacetic acid-water-acetonitrile (0.01: 92.5: 7.5) and diode array dedector [6]. The linearity of the method was studied by injecting five known concentrations of lycorine in the range of 1–10µg mL-1 and five known concentrations of galanthamine in the range of 2.5–20µg mL-1 The calibration curves for lycorine and galanthamine were determined as Y=13.2828995x + 0.4488635 and Y=10.1354031x +0.5465348, respectively. Validation procedures showed that the method was specific, accurate and precise. The above-mentioned method was applied to the aerial parts and bulbs of G.cilicicus. The contents of galanthamine and lycorine in the bulbs of G.cilicicus were found to be 0.016% and 0.0035%, respectively. In the aerial parts, lycorine was not detected, however the content of galanthamine was found as 0.015%.

Quantitative Determination of Lycorine in Galanthus xvalentinei nothosubsp. subplicatus

Galanthus xvalentinei (J. Allen) Beck nothosubsp. subplicatus (N. Zeybek) A. P. Davis (Amaryllidaceae) is a hybrid between G. nivalis L. and G. plicatus M. Bieb. subsp. byzantinus (Baker) D. A. Webb. This Galanthus L. hybrid is endemic and it occurs naturally in north-western Turkey [1,2]. Lycorine, a common alkaloid found in Amaryllidaceae plants, has been shown to possess important biological activities including antiviral [3], cytotoxic [4] and antimalarial activities [5]. In the present study, a reversed-phase high-performance liquid chromatographic method has been used for the quantitative determination of lycorine in the aerial parts and bulbs of G. xvalentinei nothosubsp. subplicatus [6]. A simple method for the extraction of lycorine in low-mass plant samples was employed utilizing pre-packed columns with diatomaceous earth (Extrelut®) [7]. The chromatographic separation was carried out using an isocratic system with a mobile phase of trifluoroacetic acid-water-acetonitrile (0.01: 95: 5) applied at a flow rate of 1mL min-1 using diode array dedector. The linearity of the method was studied by injecting five known concentrations of lycorine in the range of 0.5–8µg mL-1. The calibration curve for lycorine was determined as Y=14.9668622x + 0.7717199. The content of lycorine in the bulbs of G. xvalentinei nothosubsp. subplicatus was found to be 0.0028%. Lycorine was not detected in the aerial parts of this hybrid.

Buoyancy-Corrected Gravimetric Analysis of Lightly Loaded Filters

Numerous sources of uncertainty are associated with the gravimetric analysis of lightly loaded air filter samples (<100 μg). The purpose of the study presented here is to investigate the effectiveness and limitations of air buoyancy corrections over experimentally adjusted conditions of temperature (21–25 °C) and relative humidity (RH) (16–60% RH). Conditioning (24 hr) and weighing were performed inside the Archimedes M3 environmentally controlled chamber. The measurements were performed using 20 size-fractionated samples of resuspended house dust loaded onto Teflo (PTFE) filters using a Micro-Orifice Uniform Deposit Impactor representing a wide range of mass loading (7.2–3130 μg) and cut sizes (0.056–9.9 μm). By maintaining tight controls on humidity (within 0.5% RH of control setting) throughout pre- and postweighing at each stepwise increase in RH, it was possible to quantify error due to water absorption: 45% of the total mass change due to water absorption occurred between 16 and 50% RH, and 55% occurred between 50 and 60% RH. The buoyancy corrections ranged from −3.5 to +5.8 μg in magnitude and improved relative standard deviation (RSD) from 21.3% (uncorrected) to 5.6% (corrected) for a 7.2 μg sample. It is recommended that protocols for weighing low-mass particle samples (e.g., nanoparticle samples) should include buoyancy corrections and tight temperature/humidity controls. In some cases, conditioning times longer than 24 hr may be warranted.

HPLC - DAD Analysis of Lycorine in Amaryllidaceae Species

Lycorine, the most frequent alkaloid found in Amaryllidaceae plants, has been proven to have various biological activities. Therefore, it is important to quantify this compound in Amaryllidacaeae species. In this study, a reversed-phase high-performance liquid chromatographic method has been used and validated for the determination of lycorine in Amaryllidaceae plants. A simple method for the extraction of lycorine in low-mass plant samples was employed utilizing columns pre-packed with diatomaceous earth (Extrelut). This method was applied to the aerial parts and bulbs of Sternbergia sicula Tineo ex Guss., S. lutea (L.) Ker-Gawl. ex Sprengel and Pancratium maritimum L. (Amaryllidaceae) collected during two different vegetation periods. The chromatographic separation was performed using an isocratic system with a mobile phase of trifluoroacetic acid-water-acetonitrile (0.01:90:10) applied at a flow rate 1 mL min(-1) using diode array detector. Validation procedures showed that the method was specific, accurate and precise. The amount of lycorine in S. sicula samples ranged between 0.10-0.53%, whereas in those of S. lutea and P. maritimum, the range was 0.19-0.40% and 0.05-0.14%, respectively.