Pre-concentration of rosuvastatin using solid-phase extraction in a molecularly imprinted polymer and analytical application in water supply

In this work, it is shown the development and validation of innovative analytical methodology based on solid-phase extraction (SPE) with molecularly imprinted polymers (MIP) as a sorbent associated to UV–Vis spectroscopy to isolate and quantify, respectively, rosuvastatin (RSV) in water samples. For this purpose, porogenic solvent in MIP synthesis and SPE extraction parameters for MIP and non-imprinted polymers (NIP) were evaluated univariately for comparison purposes. The sorptive capacity and characterization studies by infrared spectroscopy and atomic force microscopy showed difference between MIP and NIP. The selectivity study of the MIP–RSVagainst other statins (simvastatin and atorvastatin) showed that the synthesized MIP can also be applied as a solid phase for isolation and quantitative pre-concentration of RSVand atorvastatin. The conjugation of SPE and UV–Vis spectroscopy in the determination of RSV in aqueous matrices led to large factor of pre-concentration (125 times), limit of detection (LOD) of 3 μg L−1, limit of quantification (LOQ) of 10 μg L−1, precision of 2.87% (n = 10), and accuracy of 83.1% (n = 4)

Square-wave voltammetric determination of primaquine in urine using a multi-walled carbon nanotube modified electrode

The electrochemical process involving primaquine was studied at a glassy carbon (GC) electrode modified with multi-walled carbon nanotubes (MWCNT). The GC/MWCNTs electrode promoted an intense oxidation peak for primaquine, improving signal when compared to the one observed using bare GC as electrode. Besides the increasing in active electrode area, the MWCNTs seemed to provide faster electron transfer. The linear analytical response for primaquine, in the concentration range from 0.1 to 5.0 μmol L−1, was achieved on a supporting electrolyte consisting of Britton-Robinson buffer (0.02 mol L−1; pH 7.00) and KCl (0.25 mol L−1). The quantitative assay using square-wave voltammetry was performed by successive additions of standard into the electrochemical cell, containing the sample, with instrumental limit of detection (LOD) of 7.3 μg L−1 (28 nmol L−1). A procedure involving liquid-liquid extraction and thin-layer chromatography provided selectivity and pre-concentration required for the determination of traces of primaquine in urine samples (LOD of the method of 146 ng L−1). Recoveries in urine samples were statistically similar to the one achieved by HPLC

Determination of Kresoxim-Methyl in Water and in Grapes by High-Performance Liquid Chromatography (HPLC) Using PhotochemicalInduced Fluorescence and Dispersive Liquid-Liquid Microextraction (DLLME)

A high-performance chromatographic method was developed to determine the fungicide kresoxim-methyl. Off-line photochemical derivatization was used to induce the formation of a stable and fluorescent product since the fungicide does not present natural fluorescence. Intense fluorescence at 370/430nm was achieved by treating the analyte in solution at pH 6 to ultraviolet light for 45s. The chromatographic conditions included isocratic elution with 50/ 50% (v/v) acetonitrile/water and the photochemical product appeared at a retention time of 7.2min. The short and long term stabilities of the photoproduct were evaluated and variation of less than 5% was achieved. The limits of detection in water samples and in grapes samples were 0.019mg kg1 and 0.065mg kg1 of kresoxim-methyl residue, respectively. The linear response covered three orders of magnitude up to 10.6mg kg1 of kresoxim-methyl. The robustness was evaluated through a Box–Behnken experimental design showing the insignificance of all factors and their interactions. The potential interference of tebuconazole for the determination of kresoxim-methyl was studied. The use of the dispersive liquid-liquid microextraction (DLLME) allowed recoveries between 80% and 101% depending on concentration with the minimum generation of waste products

Transancestral mapping and genetic load in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with marked gender and ethnic disparities. We report a large transancestral association study of SLE using Immunochip genotype data from 27,574 individuals of European (EA), African (AA) and Hispanic Amerindian (HA) ancestry. We identify 58 distinct non-HLA regions in EA, 9 in AA and 16 in HA (B50% of these regions have multiple independent associations); these include 24 novel SLE regions (Po5 10 8), refined association signals in established regions, extended associations to additional ancestries, and a disentangled complex HLA multigenic effect. The risk allele count (genetic load) exhibits an accelerating pattern of SLE risk, leading us to posit a cumulative hit hypothesis for autoimmune disease. Comparing results across the three ancestries identifies both ancestry-dependent and ancestry-independent contributions to SLE risk. Our results are consistent with the unique and complex histories of the populations sampled, and collectively help clarify the genetic architecture and ethnic disparities in SL

Experimental Study of the Impact of Trace Amounts of Acetylene and Methylacetylene on the Synthesis, Mechanical and Thermal Properties of Polypropylene

During the production of polymer-grade propylene, different processes are used to purify this compound and ensure that it is of the highest quality. However, some impurities such as acetylene and methyl acetylene are difficult to remove, and some of these impurities may be present in the propylene used to obtain polypropylene, which may have repercussions on the process. This study evaluates the impact of these acetylene and methyl acetylene impurities on the productivity of the polypropylene synthesis process and on the mechanical and thermal properties of the material obtained through the synthesis of eight samples with different concentrations of acetylene and eight samples with different concentrations of acetylene. We discovered that for the first concentrations of both acetylene (2 and 3 ppm) and methyl acetylene (0.03 and 0.1), the MFI, thermal recording, and mechanical properties of the resin were unaffected by the variation of the fluidity index, thermal degradation by TGA, and mechanical properties such as resistance to tension, bending, and impact. However, when the concentration exceeded 14 ppm for methyl acetylene and 12 ppm for acetylene, the resistance of this resin began to decrease linearly. Regarding production, this was affected by the first traces of acetylene and methyl acetylene progressively decreasing

Iron Oxide Powder as Responsible for the Generation of Industrial Polypropylene Waste and as a Co-Catalyst for the Pyrolysis of Non-Additive Resins

For the synthesis of polymeric resins, it is of great importance to review the raw materials and the equipment to be used to avoid the presence of compounds that may affect the effectiveness of the polymerization and the characteristics of the plastic to be obtained. Iron oxide is a compound that can be present in reactors after maintenance due to the techniques used and the cleaning of this equipment, and it can affect the characteristics of the resins, reducing their quality. In this study, the presence of FeO in different concentrations was evaluated to determine its effects on the properties and pyrolysis of polypropylene resins by using X-ray refraction to determine the elements of the samples, evaluating thermal degradation by TGA, the variation in molecular weight by measuring the MFI, and the compounds obtained from pyrolysis by chromatography. The results showed that the thermal degradation decreased as the FeO concentration increased, while for the MFI, the relationship was directly proportional. The evaluation of the compounds obtained from pyrolysis showed an increase in the production of alcohols, alkynes, ketones, and acids, and a decrease in alkanes and alkenes, showing that FeO affects the properties of polypropylene and the compounds that are produced during pyrolysis

Ammonia Mediated Silver Nanoparticles Based Detection of Bisphenol A, an Endocrine Disruptor, in Water Samples after Vortex-Assisted Liquid–Liquid Microextraction

Bisphenol A (BPA), an alkylphenolic compound, is one of the most polluting and hazardous organic chemicals. Its routine detection is, however, still rather expensive due to high-cost equipment. In this context, we applied the effect caused by BPA to the optical properties of surfactant-stabilized silver nanoparticles further modified with the use of ammonia (AgNP-NH3) to develop a simple and quantitative approach for BPA determination. The experimental conditions of the AgNP-NH3 probe were adjusted to establish a stable and sensitive response toward BPA in aqueous media. The use of probe dispersion measured at a wavelength of 403 nm enabled a limit of detection of 2.0 nmol L−1 (0.5 ng mL−1), with a linear response as a function of a concentration of BPA ranging from 10 to 120 nmol L−1 (from 2.2 to 27 ng mL−1). The use of vortex-assisted liquid–liquid microextraction ensured the application of selective determination to real tap and stream water samples, with recoveries ranging from 85.0 to 111%. The protocol developed herein is simple, sensitive, and selective, does not require the use of toxic labeling agents, and can be easily adapted for the routine analysis of BPA in different real samples

Electrooxidation of trifloxystrobin at the boron-doped diamond electrode: electrochemical mechanism, quantitative determination and degradation studies

<p>The boron-doped diamond (BDD) presents attractive electrochemical sensing characteristics that are useful in analytical applications based on voltammetry and amperometry. It has a wide potential window in aqueous solutions enabling the quantification of the fungicide trifloxystrobin, measured at +1744 mV (<i>versus</i> Ag/AgCl), by square-wave anodic voltammetry in a Britton–Robinson (BR) buffer (0.04 mol L^−1; pH 4.00)/acetonitrile 70/30% v/v. The activation of the electrode was made using galvanostatic chronopotentiometry and cyclic voltammetry (CV). The linear analyte addition curve, <i>I</i><i>_p</i> (µA) = (1.0 × 10^–1 ± 4.8 × 10^–6) C (mol L⁻¹) + (8.8 × 10^–2 ± 1.1 × 10^–3); <i>R</i>² = 0.997, was obtained using amplitude of 40 mV, frequency of 30 Hz, step potential of 20 mV. The instrumental limit of detection (LOD) was 1.4 × 10^–7 mol L⁻¹ (0.058 mg L⁻¹) and the dynamic linear range covered three decades (up to 1 × 10^–5 mol L⁻¹ or 4.1 mg L⁻¹). The samples were analysed with recoveries about 80% in orange juice samples and from 92.4% to 104.0% in water samples. A study to evaluate potential interferences was made in the presence of other fungicides. Diagnostic studies indicated that oxidation of trifloxystrobin in aqueous medium at the surface of the BDD is irreversible, involving two steps, each one with two electrons. The UV degradation of trifloxystrobin was evaluated using the proposed electrochemical method and the kinetics of degradation established with half-life of 1.07 min.</p

Luminescence imaging and toxicity assessment of graphene quantum dots using in vitro models

Graphene quantum dots (GQDs) have been of high interest due to their size and optical characteristics, which improves when functional groups are added to their borders and defects. In this work, the in vitro toxicity of aqueous dispersion of GQDs (w/wo amino-functionalization) was investigated in two different cellular models (S. cerevisiae and H9c2 cell line). Results in yeast suggest that when at up to 25 % volume concentration, the effect of all tested GQDs was only inhibitory, and, in both cellular models, the toxic effect is rigorously dose-dependent. The comparison of IC50 values of all the tested GQDs reveals no significant variations among them, pointing to non-carbonized citric acid as the more toxic precursor. The obtained data suggest that functionalization makes GQDs less toxic, being the one functionalized with thioacetamide slightly more toxic, followed by the ones functionalized with thiourea and glutathione, respectively. Results confirm that their toxicity is characteristics as a whole, and not as the sum of the toxicity of the precursors. In both models, concentrations up to 2 % showed no significant toxicity. Finally, fluorescence microscopy images suggest that GQDs interact with the cellular membrane and enter in the cell, manifesting fluorescent properties