Paracetamol, caffeine and ibuprofen are found in over‐the‐counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ...ibuprofen in pharmaceutical formulations. One method is based on high‐performance liquid chromatography with diode‐array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high‐performance liquid chromatography with diode‐array detection was achieved on a C18 column (250×4.6 mm2, 5 μm) with a gradient mobile phase comprising 20–100% acetonitrile in 40 mmol L−1 phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused‐silica capillary (40 cm length, 50 μm i.d.) using 10 mmol L−1 3,4‐dimethoxycinnamate and 10 mmol L−1 β‐alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 μmol L−1 by liquid chromatography and 39, 32, and 49 μmol L−1 by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92–107% for both proposed methods.
The electrochemical oxidation of fipronil is investigated on unmodified and multi-walled carbon-nanotube (MWCNT)-modified glassy carbon electrodes (GCEs), and its amperometric determination using ...batch injection analysis (BIA) is demonstrated. An oxidation peak was observed at 1.5 V in a 0.1 mol L
−1
HClO
4
/acetone solution (50:50,
v
/
v
) on both surfaces. Although MWCNT-modified GCE provided greater sensitivity, the unmodified GCE showed low RSD value, wider linear range, and reduced adsorption of fipronil or its oxidized products on the electrode surface. A detection limit of 4.7 μmol L
−1
and linear range of 25–300 μmol L
−1
were obtained using a bare GCE. The method was applied in veterinary formulations with results in agreement with those obtained by high-performance liquid chromatography.
We report the first amperometric method for the simultaneous determination of butylated hydroxyanisole (BHA) and tert-butylhydroquinone (TBHQ) in biodiesel using batch-injection analysis (BIA) ...coupled to pulsed-amperometry. A sequence of potential pulses was selected in order to detect TBHQ and BHA separately in a single injection step at a glassy-carbon electrode. Samples were diluted in 50% v/v hydroethanolic solution with 0.1molL−1 HClO4 (supporting electrolyte) before injection using an electronic pipette. The method is highly precise (RSD<1%, n=10), fast (170 injections h−1), accurate (recovery between 100 and 110%), presents low detection limits (73 and 75nmolL−1 BHA and TBHQ, respectively), and can be easily adapted for on-site determinations.
► Amperometric simultaneous determination of antioxidants BHA and TBHQ in biodiesel. ► Simple biodiesel dilution prior to injection using an electronic pipette. ► Pulsed-amperometry provides sensitive and selective simultaneous determinations. ► Batch-injection analysis provides high precision (RSD<1%), accuracy, and speed.
Voltammetric techniques have been widely applied to determine the food antioxidant capacity/activity using different electrochemical parameters (peak current, peak potential, charge) and by ...calculating the electrochemical index (EI) using glassy-carbon electrodes (GCE). A crucial step in this analysis involves electrode cleaning that typically involves polishing of the GCE surface on alumina slurry. Probably because this procedure is well established, many works have not mentioned how residual alumina is efficiently removed after polishing, which suggests that alumina residues may be present on the GCE surface. This work demonstrates that residual alumina on GCE affects the electrochemical parameters of antioxidants (caffeic acid, gallic acid, chlorogenic acid, catechin, rutin and quercetin) and food samples (tea and wine) resulting in misleading results. We critically compare the responses of unmodified (properly cleaned) with alumina-modified GCE. The results obtained by cyclic voltammetry, differential-pulse voltammetry and square-wave voltammetry showed substantial current (and charge) increase on alumina-modified electrodes and the calculated EI was dramatically increased. Alumina immobilized on GCE likely provides adsorption sites that change the electrochemical oxidation pathway of phenolic antioxidants and may adsorb the antioxidant species or their intermediates facilitating the electron transfer between antioxidants and GCE. This explanation was evidenced by the change of the rate-determining step of the electrochemical oxidation of all antioxidants after alumina modification from diffusion-controlled to adsorption-controlled processes. The enhanced detectability provided by alumina may suggest the GCE modification for improved determination of the antioxidant capacity and activity. Considering this possibility, inter- and intra-electrode precision were evaluated and RSD values lower than 5% confirms the feasibility of the alumina-modified GCE for this purpose. On the other hand, this work highlights the need for proper electrode cleaning when a bare GCE is used for this aim.
Chronic respiratory diseases (CRDs) are an important factor of morbidity and mortality, accounting for approximately 6% of total deaths worldwide. The main CRDs are asthma and chronic obstructive ...pulmonary disease (COPD). These complex diseases have different triggers including allergens, pollutants, tobacco smoke, and other risk factors. It is important to highlight that although CRDs are incurable, various forms of treatment improve shortness of breath and quality of life. The search for tools that can ensure accurate diagnosis and treatment is crucial. MicroRNAs (miRNAs) are small non-coding RNAs and have been described as promising diagnostic and therapeutic biomarkers for CRDs. They are implicated in multiple processes of asthma and COPD, regulating pathways associated with inflammation, thereby showing that miRNAs are critical regulators of the immune response. Indeed, miRNAs have been found to be deregulated in several biofluids (sputum, bronchoalveolar lavage, and serum) and in both structural lung and immune cells of patients in comparison to healthy subjects, showing their potential role as biomarkers. Also, miRNAs play a part in the development or termination of histopathological changes and comorbidities, revealing the complexity of miRNA regulation and opening up new treatment possibilities. Finally, miRNAs have been proposed as prognostic tools in response to both conventional and biologic treatments for asthma or COPD, and miRNA-based treatment has emerged as a potential approach for clinical intervention in these respiratory diseases; however, this field is still in development. The present review applies a systems biology approach to the understanding of miRNA regulatory networks in asthma and COPD, summarizing their roles in pathophysiology, diagnosis, and treatment.
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•Selective screening of a prohibited stimulant in natural herbal formulations.•Robust portable system for on-site analysis of sibutramine.•Simple and easy sample manipulation step.
...Sibutramine is one of the most widespread adulterants encountered in herbal formulations or dietary supplements used for weight-loss purposes. In this work, a simple and portable square-wave voltammetric (SWV) method was proposed for fast screening and quantification of sibutramine in herbal formulations and dietary supplements samples. The selective determination of sibutramine was possible using 0.1 mol L−1 H2SO4 solution as the supporting electrolyte and boron-doped diamond (BDD) as the working electrode. The screening of the samples is possible after a simple sample preparation procedure (dissolution in supporting electrolyte) and subsequent fast SWV scan with reliable indication of the presence or absence of sibutramine. Under optimized conditions, the determination of sibutramine is also possible with a linear working range from 5 to 50 mg L−1 (r > 0.99) and detection limits varying from 0.08 to 1.94 mg L−1 (depends on the type of sample). Moreover, it was demonstrated that the SWV developed method can be easily adapted to a portable batch-injection analysis (BIA) system aiming fast and on-site screening procedures.
Three-dimensional printing techniques have been widely used in the fabrication of new materials applied to energy, sensing and electronics due to unique advantages, such as fast prototyping, reduced ...waste generation, and multiple fabrication designs. In this paper, the production of a conductive 3D-printing filament composed of Ni(OH)2 microparticles and graphene within a polylactic acid matrix (Ni-G-PLA) is reported. The nanocomposite was characterized by thermogravimetric, energy-dispersive X-ray spectroscopic, scanning electronic microscopic, Raman spectroscopic and electrochemical techniques. Characteristics such as printability (using fused deposition modelling), electrical conductivity and mechanical stability of the polymer nanocomposite were evaluated before and after 3D printing. The novel 3D-printed disposable electrode was applied for selective detection of glucose (enzyme-less sensor) with a detection limit of 2.4 μmol L−1, free from the interference of ascorbic acid, urea and uric acid, compounds typically found in biological samples. The sensor was assembled in a portable electrochemical system that enables fast (160 injection h−1), precise (RSD < 5%) and selective determination of glucose without the need of enzymes (electrocatalytic properties of the Ni-G-PLA nanocomposite). The obtained results showed that Ni-G-PLA is a promising material for the production of disposable sensors for selective detection of glucose using a simple and low-cost 3D-printer.
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•Production of a conductive 3D-printing filament composed by nickel microparticles and graphene within a PLA matrix.•Fast 3D printing of disposable electrodes for selective detection of glucose (enzyme-less sensor).•Single step fabrication of electrodes modified with nickel nanoparticles.•Direct printing of modified electrodes.
This essay outlines the historical context in which the Feighner criteria emerged; reconstructs, as far as possible, the process by which the criteria were developed; and traces the influence the ...criteria had on subsequent developments in American psychiatry. In the 1950s, when American psychiatry under psychoanalytic dominance had little interest in psychiatric diagnosis, Edwin Gildea recruited to the Department of Psychiatry at Washington University faculty who advocated a medical model for psychiatry in which diagnosis had a central role. In 1967, at the urging of the then-resident John Feighner, a discussion group led by Eli Robins and including Sam Guze, George Winokur, Robert Woodruff, and Rod Muñoz began meeting with the initial goal of writing a review of prior key contributions to psychiatric diagnosis. In their meetings over the next year, the task soon shifted to the development of a set of new diagnostic criteria. For three diagnoses, major depression, antisocial personality disorder, and alcoholism, the authors could identify the original criteria from which this group worked and the rationale for many of the changes they introduced. Published in 1972, the Feighner criteria were soon widely cited and used in research, and they formed the basis for the development of the Research Diagnostic Criteria, which in turn were central to the development of DSM-III. The team that developed the Feighner criteria made three key contributions to psychiatry: the systematic use of operationalized diagnostic criteria; the reintroduction of an emphasis on illness course and outcome; and an emphasis on the need, whenever possible, to base diagnostic criteria on empirical evidence.
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