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A wide size range of SiO 2 particles were synthesized and were used as enzyme immobilization carriers to fabricate glucose biosensors. The size of the particles was in the range of 17–520nm. These biosensors could be operated under physiological conditions (0.1M phosphate buffer, pH 7.2). Particle size could affect the performance of SiO 2 modified glucose biosensors drastically. The...
This work reports the use of adsorptive stripping voltammetry (AdSV) for the determination of aluminium on a rotating-disc bismuth-film electrode (BiFE). Al(III) ions in the non-deoxygenated sample were complexed with cupferron and the complex was accumulated by adsorption on the surface of the preplated BiFE. The stripping step was carried out by using a square-wave (SW) potential-time voltammetric...
A novel host inclusion complex of cross-linking-polymeric-β-cyclodextrin-o-vanillin furfuralhydrazone (β-CDP-OVFH) was synthesized and characterized with IR and 1 H NMR spectra to confirm its structure. A highly selective and sensitive fluorescent determination of trace amounts of gallium was proposed based on the reaction between Ga 3+ with β-CDP-OVFH in acetic acid–ammonium acetate...
Wavelength modulation surface plasmon resonance biosensors (SPR) using colloidal Au nanoparticles and double-linker sensing membrane enhancement are reported for determination of transferrin. The 2-mercaptoethylamine (MEA) was immobilized on the biosensor surface with traditional amine coupling method. The interaction between colloidal Au nanoparticles and MEA was investigated. The anti-transferrin...
This paper reviews the practical applications of solid phase microextraction-High performance liquid chromatography in the analysis of toxic metal species as these are important contaminants and are carcinogenic. Their determination in formulations, in feed and food, and in complex environmental matrices (e.g., waste water and industrial effluents) often requires analytical methods capable of high...
A novel reversed-phase HPLC method for the simultaneous determination of active component terbinafine, its one impurity 1-methylaminomethylnaphtalene and three degradation products, β-terbinafine, Z-terbinafine and 4-methyl-terbinafine occurring in pharmaceutical formulations after long-term stability tests, was developed and validated using propylparaben as an internal standard.The chromatographic...
A sensitive method for determination of ephedrine derivatives using headspace solid-phase microextraction (SPME) with a novel fiber followed by capillary electrophoresis has been developed. The co-poly(butyl methacrylate/hydroxy-terminated silicone oil) (BMA/OH-TSO) was used as stationary phases with the aid of γ-methacryloxypropyltrimethoxysilane (KH-570) as bridge in SPME using sol–gel-coating method...
The monodisperse, 5.0μm non-porous poly(glycidylmethacrylate-co-ethylenedimethacrylate) (P GMA/EDMA ) beads were prepared by a single-step swelling and polymerization method. The seed particles prepared by dispersion polymerization exhibited good absorption of the monomer phase. Based on this media, a weak cation exchange (WCX) stationary phase for high performance liquid chromatography (HPLC)...
Equilibrium analysis of the system with MgNH 4 PO 4 ·6H 2 O (struvite) is taken as an interesting example of two-phase system where a change in solid phase composition (conversion) is affected by hydrolytic phenomena. The problem is presented in a comprehensive manner, based on results obtained from calculations made according to iterative computer program. The complex nature...
Based on the sensitizing effect of formic acid on the chemiluminescence (CL) reaction of polyhydroxylbenzenes with acidified potassium permanganate and the combination technique of high-performance liquid chromatography (HPLC), a sensitive, selective and simple post-column CL detection method for simultaneously determining catechol, resorcinol, hydroquinone and 1,2,4-benzenetriol is described. The...
Four flavonoids (rutin, hyperoside, quercitrin and quercetin) in Houttuynia cordata Thunb. and Saururus chinensis (Lour.) Bail. were determined by capillary electrophoresis with wall-jet amperometric detection. The working electrode was a 500μm diameter carbon disc electrode and the detection potential was +0.95V (versus Ag/AgCl). Effects of several important factors, such as the running buffer and...
In this paper, two chiral stationary phases were prepared by coating the surface of both C8 and C18 high-performance liquid chromatography (HPLC) supports with the teicoplanin chiral selector. The hydrophobic C11 acyl side chain, attached to the d-glucosamine group of teicoplanin, served as anchor moiety for the immobilization of the chiral selector on the apolar support material. The retention and...
In this work, a hydrophilic clay, Na-montmorillonite from Wyoming, USA, was rendered organophilic by exchanging the inorganic interlayer cations for hexadecyltrimethylammonium ions (HDTA), with the formulae of [(CH 3 ) 3 N(C 16 H 33 )] + ion. Based on fact that organo-clay has high affinities for non-ionic organic molecules, 1,3,4-thiadiazole-2,5-dithiol was...
The use of several designs of amperometric enzymatic biosensors based on the immobilized tyrosinase enzyme (Tyr) for determining dichlorvos organophosphate pesticide are described. The biosensors are based on the reversible inhibition of the enzyme and the chronocoulometric measurement of the charge due to the charge-transfer mediator 1,2-naphthoquinone-4-sulfonate (NQS). Tyr becomes active when reducing...
The purpose of this work was the development of a method for the determination of Se compounds in leaves of plants. Water-soluble Se compounds were extracted from samples by water. Enzymatic hydrolysis with the non-specific enzyme protease XIV was used for the release of Se compounds bound to proteins. Separation of Se species was made by ion exchange chromatography, using an anion exchange column...
A simple, fast and relatively inexpensive spectrophotometric method for the identification and the quantification of the individual components of the Italian general denaturant in alcohol samples is proposed.In particular, it is shown that bitrex (a quaternary ammonium salt), whose UV spectrum is completely masked by those of the other denaturant components, can be identified using its reaction with...
A new photocatalytic system, nano-TiO 2 –Ce(SO 4 ) 2 coexisted system, which can be used to determine the low chemical oxygen demand (COD) is described. Nano-TiO 2 powders is used as photocatalyst in this system. The measuring method is based on direct determination of the concentration change of Ce(IV) resulting from photocatalytic oxidation of organic compounds. The...
Eighteen-nanometer gold and 3.5-nm silver colloidal particles closely packed by cetyltrimethylammonium bromide (CTAB) to form its positively charged shell. The DNA network was formed on a mica substrate firstly. Later, CTAB–capped gold or silver colloidal solutions were cast onto DNA network surface. It was found that the gold or silver nanoparticles metallized networks were formed owing to the electrostatic-driven...
An experiment was developed as a simple alternative to existing analytical methods for the simultaneous quantitation of glucose (substrate) and glucuronic acid (main product) in the bioprocesses Kombucha by using FTIR spectroscopy coupled to multivariate calibration (partial least-squares, PLS-1 and artificial neural networks, ANNs). Wavelength selection through a novel ranked regions genetic algorithm...
The performance of a new graphite–castor oil polyurethane composite electrode in the determination of hydroquinone in photographic developers in a differential pulse voltammetric (DPV) procedure is described. The 60% (graphite, w/w) composite electrode presented good stability, repeatability and accurate response. Limit of detection of 934nmolL −1 was observed for hydroquinone within a linear...
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