Showing papers in "Analytica Chimica Acta in 1990"

TL;DR: In this paper, a new approach to automated analysis is designed to fill a gap in present flow-injection methodology, which is based on the random walk model and sequential injection analysis.

TL;DR: In this paper, a total of 74 chapters of which 68 are devoted to individual elements and derived substances are presented, including radiotoxicity, chemistry and distribution, technological uses, physiological processes, detoxification mechanisms, levels of tolerance, summary of ecotoxicity, and analytical chemistry as well as a list of references.

TL;DR: In this article, the effects of molecular parameters and environmental factors (molecular weight, concentration, pH, ionic strength, temperature and redox potential) on the fluorescence behavior of fulvic acids are discussed.

TL;DR: In this paper, the compositional differences between fulvic acids and humic acids from soil, stream and marine environments by five different methods (1H and 13C NMR spectroscopy, 14C age and δ13C isotopic analyses, amino acid analyses, pyrolysis-mass spectrometry).

TL;DR: In this paper, a novel material for separations has been developed in which efficient chromatographic particles are enmeshed in a network of PTFE fibrils to form a strong, porous sheet or "membrane".

TL;DR: In this article, a method was developed to isolate quantitatively the actinide elements (as a group) from urine samples and to produce near massless electrodeposits suitable for high-resolution α-spectrometry.

TL;DR: A review of the application of electron spin resonance (ESR) spectroscopy to the study of the chemistry of fulvic acid and its interactions with paramagnetic metal ions is presented in this paper.

TL;DR: In this article, the effects of variation of acidity and molybdate concentration on the spectrophotometric determination of phosphate by the method of Murphy and Riley were studied, and the [H+]:[Mo] ratio was found to be a crucial parameter which not only influences the form of the final reduced complex, but also plays a key role in controlling the reaction kinetics.

TL;DR: In this paper, Boron, Aluminum, Gallium, Indium, and Thallium are classified as the Halogens: Fluorine, Chlorine, Bromine, and Iodine.

TL;DR: In this article, a carbon-paste chemically modified with glucose oxidase and a ferrocene-containing siloxane polymer was further modified by coating the electrode surface with a poly(ester-sulfonic acid) cation-exchanger, Eastman AQ-29D.

TL;DR: In this article, a matrix-assisted laser desorption/ionization mass spectrometry (LDI MS) was used for desorbing ions of biomolecules with relative molecular masses (M r ) up to about 300 000 daltons.

TL;DR: In this paper, the kinetics of the reaction for the formation of the pink azo dye in both fresh water and sea water was studied at different acidities, temperatures, and concentrations of N -1 naphthylethylenediamine (NED).

TL;DR: A broad selection of the most common, recent and emerging isolation, clean-up and concentration techniques used to prepare samples for chromatographic separations are reviewed in this article, where a broad range of techniques are presented.

TL;DR: In this article, the gas chromatography of very small samples of insect pheromones and defensive secretions is described, and reaction products obtained in a very small volume (5 μl) for chromatography without evaporation.

TL;DR: In this article, a methodology based on acid-base titrations at several salt levels is presented that allows for the assessment of an appropriate electrostatic double-layer model and the intrinsic proton affinity distribution.

TL;DR: In this article, the simultaneous incorporation of ferrocene derivatives and glucose oxidase into a carbon-paste matrix results in an effective microelectrode for sensing glucose, which offers extremely short response times ( t 95% =18 s) compared with early Ferrocene-based glucose sensors.

TL;DR: In this paper, two methods to determine copper complexation in estuarine waters were compared, one based on a complete titration of the complexing capacity of the sample and the other on measurement of the labile and total dissolved metal concentrations only.

TL;DR: In this paper, an outline of the requirements for the construction of an immunological field effect transistor (ImmunoFET) which should operate on the direct potentiometric sensing of protein charges is given.

TL;DR: In this article, the authors modified silicon dioxide ion-sensitive field effect transistors by silylation with methacryloxypropyltrimethoxysilane (MPTS) and with in situ photopolymerized poly(hydroxyethyl methACrylate).

TL;DR: In this article, a new method and apparatus for the determination of organic carbon in water is described, which is suitable for analysis of water containing 0.1-30 μg ml−1 organic carbon and sample volumes of 1-40 ml.

TL;DR: The fabrication and operation of a multi-analyte miniature conductance biosensor that responds to changes in the electrode double layer capacitance as the ionic strength is increased by the enzyme-catalysed generation of charged reaction products is described.

TL;DR: In this article, a diode-array spectrophotometer is used and non-specific absorbance subtraction is exploited: the incident light passes through the flowing sample, the emergent light is dispersed, the intensities of two selected monochromatic beams are measured simultaneously by separate detectors and real-time subtraction of the wavelength-independent noise is achieved.

TL;DR: Direct electron transfer between active glucose oxidase (GOD) and a gold electrode was obtained when GOD was immobilized in poly( N -methylpyrrole) electrochemically prepared on the gold electrode as mentioned in this paper.

TL;DR: In this article, an ultra-thin layer of polypyrrole can be coated on nonconducting substrates, e.g., acrylic, by dip coating into a colloidal suspension of poly pyrrole, reversibly combines with low concentrations of ammonia or hydrazine with a concomitant reversible increase in resistance.

TL;DR: In this paper, the potential utility of these parameters for the optimization of micellar liquid chromatography and mousellar electrokinetic capillary chromatography, including selection of the surfactant and/or stationary phase, was discussed.

TL;DR: In this paper, a carbon-epoxy composite electrode modified with the electron mediator cobalt phthalocyanine was used to investigate the electrochemical behavior of ascorbic acid.

TL;DR: In this article, the results of a study in which ultrafiltration fractionation in combination with UV_VIS, fluorescence, FT-IR and NMR spectroscopy was used to characterize a stoichiometrically characterized Laurentian fulvic acid are presented.

TL;DR: In this article, the oscillating frequencies of a piezoelectric crystal were measured in various solutions for a wide range of products of density (ϱ) and viscosity (η) and in electrolyte solutions.

TL;DR: In this paper, a computer program is described for the estimation of carbon-13 chemical shifts, which automatically selects and applies the additivity rules appropriate for the individual carbon atoms of the structure entered.