Planning new Trypanosoma cruzi CYP51 inhibitors using QSAR studies

Molecular Diversity - Chagas disease kills over 10,000 people per year, and approximately 8 million people are infected by Trypanosoma cruzi. The reference drug for treatment of the disease,...     

Production of spiked vegetation samples containing γ-emitting radionuclides for proficiency testing

Journal of Radioanalytical and Nuclear Chemistry - The production of environmental reference materials such as soil, sediment, water and vegetation containing radionuclides for interlaboratory...     

The Influence of the Cathodic Pretreatment on the Electrochemical Detection of Dopamine by Poly(1‐aminoanthracene) Modified Electrode

In this study we demonstrated the influence of the cathodic pretreatment of poly(1‐aminoanthracene) (PAA) electropolymerized on a platinum electrode for determination of dopamine (DA). The DA electrochemical response was obtained after a cathodic pretreatment of the PAA electrode which consisted of applying a potential of ?0.7 V (vs. Ag/AgCl) for 3 s before each measurement. The pretreatment of the electrode changed the PAA electrocatalytic properties so that the electrode began to present electrochemical response to DA without interference of ascorbic acid (AA). The anodic peak currents determined by differential pulse voltammetry using pretreated PAA showed a linear dependence on the DA concentration from 0.56 to 100 µM with a detection limit of 0.13 µM and a correlation coefficient of 0.9986. The electrode exhibits a relative standard deviation of 1.2 % for ten successive measurements of a 0.5 mM DA solution. The analysis by scanning electron microscopy and atomic force microscopy show a homogeneous and nanostructured film with globular structures with diameter of about 20 nm. The analytical results obtained for DA determination at a pretreated PAA electrode in pharmaceutical formulation sample were in good agreement with those obtained by a comparative procedure at a 95 % confidence level. PAA electrode after the pretreatment showed electrochemical responses to DA with excellent selectivity, sensitivity, and high stability without interference of AA.     

Isobaric vapour–liquid equilibria for the binary systems 4-methyl-2-pentanone + 1-butanol and + 2-butanol at 20 and 101.3 kPa

Isobaric vapour–liquid equilibrium (VLE) measurements for the binary systems 4-methyl-2-pentanone + 1-butanol and 4-methyl-2-pentanone + 2-butanol are reported at 20 and 101.3 kPa. The system 4-methyl-2-pentanone + 1-butanol presents a minimum boiling point azeotrope at both pressures (20 and 101.3 kPa) and the system 4-methyl-2-pentanone + 2-butanol presents only a minimum boiling azeotrope at 20 kPa. In both systems, which deviate positively from ideal behaviour, the azeotropic composition is strongly dependent on pressure. The activity coefficients and boiling points of the solutions were correlated with its composition by the Wilson, UNIQUAC, and NRTL models for which the parameters are reported.     

Analysis of recombinant human erythropoietin and novel erythropoiesis stimulating protein digests by immunoaffinity capillary electrophoresis–mass spectrometry

In this work, we demonstrate that detection of a specific peptide marker by immunoaffinity capillary electrophoresis–mass spectrometry (IA-CE–MS) could be used to confirm the presence of recombinant human erythropoietin (rhEPO) in solution. Besides the carbohydrate content, the amino acid sequence of novel erythropoiesis stimulating protein (NESP) differs from human erythropoietin (hEPO) at five positions (Ala30Asn, His32Thr, Pro87Val, Trp88Asn, and Pro90Thr). After digesting both glycoproteins in solution by trypsin and PNGase F, two specific proteotypic peptides, EPO (77–97) and NESP (77–97) which differ in three amino acids, were selected as rhEPO and NESP markers, respectively. Both digests and their mixtures were analyzed by IA-CE–MS. The IA stationary phase was prepared from a custom made polyclonal anti-EPO (81–95) antibody immobilized on a solid support of CNBr-Sepharose 4B and was packed in a microcartridge near the inlet of the separation capillary. As the antibody was directed to a synthetic peptide EPO (81–95), only the proteotypic peptide EPO (77–97) was retained. The retained peptide was eluted, separated by electrophoresis and detected by MS. The method was specific to confirm the presence of rhEPO in solution. Although the limits of detection for the peptide marker were similar to those obtained with CE–MS (a few mg/L), these results show the potential of this novel approach to detect in the future rhEPO and its analogues selectively and unambiguously at the levels expected in biological fluids.     

Evolution Inclusions Governed by Time-Dependent Maximal Monotone Operators with a Full Domain

In this paper, we study the existence of solutions for evolution inclusions governed by time-dependent maximal monotone operators with a full domain. Without assumptions concerning time-regularity on the time-dependent maximal monotone operators, and by using the Moreau-Yosida regularization technique, we establish the existence of solutions in Hilbert spaces. The theoretical result is applied to prove the existence of solutions for semicoercive sweeping processes with velocity constraint.

     

Total reflection X ray fluorescence in environmental and geochemical studies: unveiling solute provenance in streams during a rain episode

Rural population uses water for irrigation, animal watering and for their own consumption, therefore water contamination is a major concern and a priority for its inhabitants. Unveiling the presence and source of contaminants can help to understand the dynamic of pollutants and therefore define management politics to address the issue. One way to elucidate the origin of contaminants in surface water is by studying rain episodes, relating water discharge with changes in solute concentration. Total Reflection x‐ray Fluorescence (TXRF) was used as the main analytical technique. The study was based on the analysis of samples originating from a Pampean stream (Buenos Aires, Argentina). Solutes (As, P, Ca, Fe, K, Zn, Br) were monitored before, during and after a storm event. During the monitoring it was observed that As was diluted at the beginning of the episode and concentration increased slowly after the rain ceased. The pattern of As is consistent with Ca, K and Fe behavior, revealing a groundwater source. Instead, P concentration increased in the early hours, it was diluted later and finally increased. This behavior indicates that the source of this analyte is superficial and sub superficial water, implying a runoff origin. The simultaneous determination of these analytes by TXRF allowed comparing solute behavior under the same episode, allowing reveal their provenance. Copyright © 2016 John Wiley & Sons, Ltd.     

A Rapid and Sensitive Strip‐Based Quick Test for Nerve Agents Tabun,Sarin, and Soman Using BODIPY‐Modified Silica Materials

Test strips that in combination with a portable fluorescence reader or digital camera can rapidly and selectively detect chemical warfare agents (CWAs) such as Tabun (GA), Sarin (GB), and Soman (GD) and their simulants in the gas phase have been developed. The strips contain spots of a hybrid indicator material consisting of a fluorescent BODIPY indicator covalently anchored into the channels of mesoporous SBA silica microparticles. The fluorescence quenching response allows the sensitive detection of CWAs in the μg m^?3 range in a few seconds.     

Rapid confirmation/quantitation of cocaine and benzoylecgonine in urine utilizing high performance liquid chromatography and tandem mass spectrometry

A rapid, but sensitive and selective method for confirmation and quantitation of benzoylecgonine (BZE) and cocaine (COC) in urine by fast-gradient liquid chromatography/tandem mass spectrometry (LC/MS/MS) is described. The chromatographic separation was performed on a reversed phase column employing fast-gradient techniques. Matrix prepared standards, blanks, and QC's were filtered then aliquots were transferred into a 96 well plate. Injection volumes of 25 microL were made onto the analytical column, with the flow diverted from the atmospheric pressure ionization source for the first 0.5 min of the analysis. Simultaneous multiple reaction monitoring (MRM) of three discrete transitions for each compound were used to identify BZE and COC. Quantitation was achieved utilizing the most prominent parent-daughter transition and internal standard calibration techniques. The coefficients of variation (CV) for the analysis of these drugs ranged from 0.6% to 6.8% at a concentration of 150 ng/mL (n = 155). This method suggests that fast-gradient LC/MS/MS may be suitable for routine confirmation of immunoassay cocaine-positive samples.