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A simple and reproducible carbon microelectrode array (CMA), designed to eliminate diffusive interference among the microelectrodes, has been fabricated and used as a frame to build a gold (Au) microelectrode array (GMA) sensor. To prepare the CMA initially, rather than use an uncontrollable large number of carbon fibers, only 60 carbon fibers of regular size were used to ensure manageable and reproducible...
The advantages and shortcomings of focused microwave-induced combustion (FMIC) for digestion of plant samples were studied. The effects of sample mass, absorbing solution, oxygen gas flow-rate, and time of reflux step on recoveries of major, minor and trace metals were systematically evaluated. Afterwards, Al, Ba, Ca, Co, Cr, Cu, Mg, Mn, Ni, Sr, V, and Zn were determined by inductively coupled plasma...
The influence of different Purge Times on the effectiveness of Pressurized Liquid Extraction (PLE) of volatile oil components from cypress plant matrix (Cupressus sempervirens) was investigated, applying solvents of diverse extraction efficiencies. The obtained results show the decrease of the mass yields of essential oil components as a result of increased Purge Time. The loss of extracted components...
A simple solid phase extraction system based on the applying the nickel–aluminum layered double hydroxide (Ni–Al LDH) as a nano-sorbent was developed for the speciation analysis of chromium and manganese by flame atomic absorption spectrometry (FAAS). The method is based on the fact that Cr(VI) and Mn(VII) oxyanions could be adsorbed on the Ni–Al(NO 3− ) LDH and/or exchanged with LDH...
This work introduces the monosegmented flow-batch (MSFB) analysis concept. This system combines favourable characteristics of both flow-batch and the monosegmented analysers, allowing use of the flow-batch system for slow reaction kinetics without impairing sensitivity or sampling throughput. The MSFB was evaluated during spectrophotometric determination of boron in plant extracts, which is a method...
A near-infrared-emitting CdTe/CdS core/shell quantum dots (QDs)-based photoluminescence (PL) sensor was designed and applied for highly selective and sensitive detection of Cd 2+ . This sensor was based on a PL “OFF–ON” mode. First, the addition of ammonium pyrrolidine dithiocarbamate (APDC) led to remarked PL quenching of QDs. Second, PL of APDC surface modified QDs (QDs-APDC) was gradually...
This paper presents the development, characterization and quality control of analytical methods based on the use of disposable optical sensors for determination of heavy metals. Chromogenic reagents such as 1-(2-pyridylazo)-2-naphthol, (2-pyridylazo)resorcinol, Zincon, Ferrozine, and Chromazurol S were used to develop optical sensors of heavy metal ions found as contaminants in pharmaceutical substances...
Although the basic science behind current methods for studying biopharmaceutical drug stability has not changed significantly, the techniques available for predicting stability have evolved over the years. This paper therefore describes and discusses various options of data analysis for accelerated degradation studies of peptide and protein drugs based on the Arrhenius equation. Both linear and non-linear...
The two main goals of the analytical method described herein were to (1) use principal component analysis (PCA), hierarchical clustering (HCA) and K-nearest neighbors (KNN) to determine the feedstock source of blends of biodiesel and conventional diesel (feedstocks were two sources of soy, two strains of jatropha, and a local feedstock) and (2) use a partial least squares (PLS) model built specifically...
A new protocol using zincon-immobilized silica-coated magnetic Fe 3 O 4 nanoparticles (Zincon–Si–MNPs) as solid-phase extraction (SPE) medium has been developed for the separation and preconcentration of trace lead in water. Various parameters such as pH, extraction time, concentration and volume of eluent, sample volume, and influence of co-existing ions have been investigated in...
A gold interdigitated microelectrode (IME) impedance biosensor was fabricated for the detection of viable Escherichia coli O157:H7. This sensor was fabricated using lithography techniques. The surface of the electrode was immobilized with anti-E. coli IgG antibodies. This approach is different from other studies where the change in impedance is measured in terms of growth of bacteria on the electrode,...
We previously reported a colorimetric assay method for Co 2+ based on the thioglycolic acid (TGA) functionalized hexadecyl trimethyl ammonium bromide (CTAB) modified Au NPs. However, the detection limit of 3×10 −7 M was still higher than that of the sanitary standard for drinking water (6.8×10 −8 M). In addition, the interactions between the modifier and Au NPs, and between...
Sample preparation is a critical step for all kind of biological fluids analysis with serious implications in data retrieved. In this sense, efforts have been made to standardize biofluids’ management procedures for diagnosis and research purposes. However, no agreement exists regarding saliva preparation. Aiming the delineation of an ideal preparation procedure for salivary peptidome analysis, the...
A heterogeneous immunoassay for monensin determination in milk samples using a tracer formed by anti-monensin antibodies bound to nile blue (NB)-doped silica nanoparticles (NPs), 96-well microplates as solid supports and long-wavelength fluorescence measurements is described for the first time. The assay relies on the competition of the monensin present in the samples with a monensin–bovine serum...
Rhodamine 6G (R6G) and 3-mercaptopropionic acid (MPA) capped-CdTe quantum dots (QDs) were conjugated by electrostatic interactions in aqueous solution. The R6G-QDs conjugate was utilized as a photoluminescence (PL) ratiometric sensor for the detection of glutathione (GSH). In this method, intentional introduction of GSH destroyed the conjugation of R6G and QDs, and induced regular PL change of R6G-QDs...
An assay for quantitative analysis of phosphatidylcholine (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and its hydrolysis products: 1-hydroxy-2-palmitoyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine, sn-glycero-3-phosphocholine and palmitic acid using high-performance liquid chromatography with charge aerosol detector (CAD) was developed. The separation of the...
The surface of raw multicrystalline silicon wafers is treated with HF–HNO 3 mixtures in order to remove the saw damage and to obtain a well-like structured surface of low reflectivity, the so-called texture. The industrial production of solar cells requires a consistent level of texturization for tens of thousands of wafers. Therefore, knowing the actual composition of the etch bath is a key...
An inductively coupled plasma optical emission spectrometry quantification method for the determination of Al, Ca, Cr Cu, Fe, Mn, Mg, Ni, Zn, Ba, K, In and Co in lead zirconate-titanate (PZT) ceramics, modified with strontium and chromium, was developed. Total digestion of ceramics was achieved with a HNO 3 , H 2 O 2 and HF (ac) mixture by using a microwave furnace. The sensitivity...
In this contribution, bovine serum albumin stabilized gold nanoclusters as novel fluorescent probes were successfully utilized for the detection of ciprofloxacin for the first time. Our prepared gold nanoclusters exhibited strong emission with peak maximum at 635nm. Cu 2+ was employed to quench the strong fluorescence of the gold nanoclusters, whereas the addition of ciprofloxacin caused the...
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