The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A liquid-core waveguide made of Teflon AF-2400 has been used to construct a simple, sensitive and robust instrument capable of performing fluorimetric and spectrophotometric analyses on aqueous solutions. The instrument, which uses a CCD array detection system, is unique in that high performance is achieved for both measurement techniques with minimal changes in instrument configuration. The fluorimetric...
The ability of Chlorella vulgaris to accumulate heavy metals in solution (Mn, Cr, Ni, Zn and Cu) was investigated. Various parameters (algal biomass, pH and contact time of the algae with the sample) have been studied. Nine mg of algal biomass, pH 8 and 15 min of contact time, with 1 ppm of each metal, were the optimized conditions. At pH 8, the optimum value to rise the maximum binding, a fraction...
Near-infrared (NIR) squarylium dye spectral properties were evaluated by absorption, fluorescence, circular dichroism (CD), and fluorescence-detected circular dichroism (FDCD). Substituents of the two NN dyes differed at R 1 and R 2 , located symmetrically on the chromophore. The side chains of NN525 are R 1 =hexanoic acid, R 2 =butyl sulfonate and R 1 =R ...
Bisphenol A (BPA) in the presence of phenol is determined using a method based on first-derivative spectrofluorimetry. The proposed method involves a micro liquid-liquid extraction of sodium chloride saturated water samples with diethyl ether followed by direct fluorimetric analysis of extracts. The excitation spectra of both compounds in diethyl ether are recorded between 200 and 290 nm, with the...
An on-line wavelet transform algorithm and development of voltammetric analyzer with the on-line wavelet transform (WT-voltammetric analyzer) are described. Because the on-line wavelet transform decomposes the sampled signal simultaneously with the progress of sampling, the WT-voltammetric analyzer gives all the components contained in the sampled voltammogram. Applications of the WT-voltammetric...
Biomembrane-like polyionic complex, 2C 12 N + PA - , was prepared by reacting sodium polyacrylate (Na + PA - ) with didodecyldimethylammonium bromide (2C 12 N + Br - ). Stable thin films made from 2C 12 N + PA - , with incorporated myoglobin (Mb), on pyrolytic graphite (PG) electrodes were then characterized...
A method for the determination of the major serotonin metabolite - 5-hydroxyindole-3-acetic acid (5-HIAA) in human gastric juice by cyclic voltammetry was described. The measurement conditions were investigated. The potential window was chosen from +0.1 to +0.9 V, the supporting electrolyte was 0.025 M PBS solution (pH 2.0). The method allowed determination in the concentration range from 2.0 x10...
This paper describes the design of a hot-wire electrochemical flow detector, and the advantages accrued from the effects of locally increased temperature, mainly thermally induced convection, upon the amperometric monitoring of flowing streams. A new hydrodynamic modulation voltammetric approach is presented, in which the solution flow rate remains constant while the temperature of the working electrode...
The electrogenerated chemiluminescent (ECL) behavior of hemin at a platinum electrode in the alkaline solution has been investigated in detail. Under the optimum conditions the linear response range of hemin is 1.0x10 -5 -1.0x10 -8 g ml -1 , the detection limit was 1.0x10 -8 g ml -1 , and the relative standard derivation for 1x10 ...
Speciation of iron in milk was carried out by high performance liquid chromatography (HPLC) and electrothermal atomic absorption spectrometry (ETAAS). Milk whey was obtained and low molecular weight protein separation was performed by size exclusion chromatography (SEC) with a TSK Gel SW glass guard (Waters) pre-column and a TSK-Gel G2000 glass (Toso Haas) column. After studying water as a possible...
Mercury-thin film electrodes coated with a thin film of poly(ester sulphonic acid) (PESA) have been investigated for application in the analysis of trace heavy metals by square wave anodic stripping voltammetry using the batch injection analysis (BIA) technique. Different polymer dispersion concentrations in water/acetone mixed solvent are investigated and are characterised by electrochemical impedance...
Flow injection titration was used for the determination of anionic, cationic, nonionic and zwitterionic surfactants. The procedure was based on the micellar-enhanced fluorescence of 1,8-anilino-naphthalene sulfonate (ANS). Samples were injected into a carrier stream of phosphate buffer and 1.0 mol l -1 NaCl. The sample then passed through a mixing chamber which generated the exponential...
The analysis of explosives with ion mobility spectrometry (IMS) directly from aqueous solutions was shown for the first time using an electrospray ionization technique. The IMS was operated in the negative mode at 250 o C and coupled with a quadrupole mass spectrometer to identify the observed IMS peaks. The IMS response characteristics of trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT),...
A simple method for simultaneous determination of three catecholamines using ion chromatography (IC) with direct conductivity detection (CD) based on the ionization of catecholamines in acidic medium without chemical suppression is developed in the present paper. The method could be used for the determination of these catecholamines in pharmaceutical preparations for the purpose of drug quality control...
A novel hydrogen peroxide (H 2 O 2 ) potentiometric sensor, made with a MnO 2 -doped carbon paste electrode (CPE), is reported. Under optimum conditions, the electrode gives a Nernstian response for H 2 O 2 in the concentration range 3.00x10 -7 -3.63x10 -4 mol/l, with a slope of 21-19.4 mV/pH 2 O 2 and a detection limit...
A procedure for separation and preconcentration of trace amounts of copper in natural water samples, has been proposed. It is based on the adsorption of copper(II) ions onto a column of Amberlite XAD-2 resin loaded with calmagite reagent. This way amounts of copper within the range from 0.0125 to 25.0 μg, in a sample volume of 25 to 250 ml, and pH from 3.7 to 10.0 was concentrated as calmagite complex...
Homocysteine present in human blood plasma is derivatized with thiol selective ultraviolet labelling reagent, 2-chloro-1-methylpyridinium iodide, and separated from other plasma thiol derivatives by high-performance liquid chromatography (HPLC) with detection at 312 nm. The separation is carried out isocratically on LiChrospher RP-18 column using mobile phase consisting of pH 2.5 0.04 M trichloroacetic...
A new bulk acoustic wave (BAW) cellulase sensing technique, which is based on the enzymatic hydrolysis process of sodium carboxymethylcellulose (CMC) by cellulase, was established. The frequency shift curves of BAW sensor indicated that the viscosity of the tested solutions decreased during the hydrolysis process. The hydrolysis rate of CMC by cellulase was calculated from the frequency shift curves...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.