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Nitrogen doping has been a powerful method to modulate the properties of carbon materials for various applications, and N-doped graphene quantum dots (GQDs) have gained remarkable interest because of their unique chemical, electronic, and optical properties. Herein, we introduce a facile one-pot solid-phase synthesis strategy for N-doped GQDs using citric acid (CA) as the carbon source and 3,4-dihydroxy-l-phenylalanine...
A strategy for designing valid standard addition calibrations and for optimising their uncertainty is presented. The design of calibrations involves the development of models of the sensitivity and precision of the instrumental signal, in a wide range of analyte concentration (or any other studied quantity), and the definition of sample dilution and standard addition procedures that allow fulfilling...
A strategy for a label-free impedimetric immunosensor is described for detection of the textile dye Disperse Orange 1 (DO1). The compounds 1,12-diaminododecane (DADD) and then 1,7-diaminoheptane (DAH) were firstly successively grafted onto a glassy carbon electrode (GCE) surface by electro-oxidation of one amino group, while the other terminal amino group was modified with the antibody anti-DO1. The...
An optimized analytical method based on C8 core-shell reverse phase chromatographic separation and high resolution mass spectral (HRMS) detection is developed for a fast analysis of unbound phytochelatins (PCs) in plants. Its application to analysis of Clinopodium vulgare L. is demonstrated where proper PCs liberating and preservation conditions were employed using dithiotreitol in the extraction...
Recent advances in genomics, recombinant expression technologies and peptide synthesis have led to an increased development of protein and peptide therapeutics. Unfortunately this goes hand in hand with a growing market of counterfeit and illegal biopharmaceuticals, including substances that are still under pre-clinical and clinical development. These counterfeit and illegal protein and peptide substances...
A simple and sensitive electroanalytical method was developed for determination of nanomolar levels of Pb(II) based on the voltammetric stripping response at a carbon paste electrode modified with biochar (a special charcoal) and bismuth nanostructures (nBi-BchCPE). The proposed methodology was based on spontaneous interactions between the highly functionalized biochar surface and Pb(II) ions followed...
A new method has been developed for separation of chelerythrine and sanguinarine in medicinal plants used in traditional Chinese medicine (TCM). The separation is achieved by microchip electrophoresis (CE) using laser-induced fluorescence detection. The CE separation is achieved by using a hydro-organic medium as the electrolyte buffer. The experimental results are consistent with the prediction by...
In this paper we aim to demonstrate, as a proof-of-concept, the feasibility of the mass production of effective point of care tests for nitrite quantification in environmental, food and clinical samples. Following our previous work on the development of third generation electrochemical biosensors based on the ammonia forming nitrite reductase (ccNiR), herein we reduced the size of the electrodes'...
This paper aims to estimate the temperature equivalent to 10% (T10%), 50% (T50%) and 90% (T90%) of distilled volume in crude oils using 1H NMR and support vector regression (SVR). Confidence intervals for the predicted values were calculated using a boosting-type ensemble method in a procedure called ensemble support vector regression (eSVR). The estimated confidence intervals obtained by eSVR were...
An amperometric biosensor based on chemisorption of glucose oxidase (GOx) on Au seeds decorated on magnetic core Fe3O4 nanoparticles (Fe3O4@Au) and their immobilization on screen-printed carbon electrode bulk-modified with manganese oxide (SPCE{MnO2}) was designed for the determination of glucose. The Fe3O4@Au/GOx modified SPCE{MnO2} was used in a flow-injection analysis (FIA) arrangement. The experimental...
Label-free colorimetric assays using metallic nanoparticles have received much recent attention, for their application in simple and sensitive methods for detection of biomolecules. Short peptide probes that can bind to analyte biomolecules are attractive ligands in molecular nanotechnology; however, identification of biological recognition motifs is usually based on trial-and-error experiments. Herein,...
Celiac disease (CD) is one of the most common digestive disorders caused by an abnormal immune reaction to gluten. So far there are no available therapies, the only solution is a strict gluten-free diet, which however could be very challenging as gluten can be hidden in many food products. Furthermore an additional problem is related to cross-contamination of nominal gluten-free foods with gluten-based...
A new on-line SPE–HPLC method using fused-core columns for on-line solid phase extraction and large volume sample injection for increasing the sensitivity of detection was developed for the determination of insecticides fenoxycarb and cis-, trans-permethrin in surface waters. The separation was carried out on fused-core column Phenyl–Hexyl (100×4.6mm), particle size 2.7µm with mobile phase acetonitrile:water...
A simple, rapid, sensitive and effective method for the simultaneous determination of four endocrine disrupting compounds (EDCs) (bisphenol A (BPA), bisphenol F (BPF), bisphenol AF (BPAF) and bisphenol AP (BPAP)) in environment water samples based on solid-phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC) was developed. Multi-wall carbon nanotubes (MWCNTs) adsorbents...
Synthetic cannabinoids are an emerging class of drugs of abuse and are of a great concern for transport control and usage regulation. In this study, we have developed rapid analytical methods using a miniature mass spectrometer for the identification of synthetic cannabinoids, as the traces of bulk powders on surfaces or substances in blood and urine. Significantly simplified work flows were developed...
Immunochromatographic test strips (ICTS) are commonly limited to higher concentrations of analytes. This limitation stems from the relatively low sensitivity of conventional gold nanospheres (AuNSs with a diameter of 20nm) to emit detectable brightness values. The larger multi-branched gold nanoflowers (AuNFs) with a higher optical brightness as well as good colloidal stability exhibit significant...
In this study a new solid-state ion selective electrode which is easy to prepare and sensitive to arsenate ion concentration is prepared. The solid salts used in the electrode composition were Cu2S, Ag3AsO4 and Ag2S. The principal component of the electrode was Ag3AsO4. The measurements were made in constant ionic strength using 0.1M NaNO3 and at room temperature. The potentiometric response of electrodes...
In this work, a chemically and thermally robust and highly porous zeolite-type metal–organic framework, zeolitic imidazolate framework-8 (ZIF-8), was used as both a precursor and a template and furfuryl alcohol as a second precursor to synthesize a nanoporous carbon. The prepared ZIF-8-derived nanoporous carbon was used as the solid-phase extraction adsorbent for the extraction of carbamate pesticides...
A quantitative and confirmatory high-performance liquid chromatography with ultraviolet detection (HPLC–UV) method for the determination of bioactive amines in the albumen and yolk of commercial eggs was developed, optimized and validated by analyte extraction with trichloroacetic acid and pre-column derivatization with dansyl chloride. Phenylethylamine, putrescine, cadaverine, histamine, tyramine,...
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