Showing papers in "Analytica Chimica Acta in 1994"

TL;DR: In this paper, a separation scheme for strontium and light rare earth elements and its application to the isotopic analysis of strons and neodymium in silicate rocks are presented.

TL;DR: In this paper, a multi-method approach was used to investigate the chemical speciation of dissolved copper and nickel in South San Francisco Bay and determined dissolved copper speciation by four different analytical approaches: competitive ligand equilibration-cathodic stripping voltammetry [CLE-CSV], differential pulse anodic stripping (DPSV), DPASV(TMF-RGCDE) and chelating resin column partitioning-graphite furnace atomic absorption spectrometry [CRCP-GFAAS].

TL;DR: In this paper, a manifold based on a set of three-way solenoid valves controlled by a microcomputer using software written in QuickBASIC was proposed to handle sample and reagent introduction in continuous flow systems.

TL;DR: In this paper, a three-stage sequential extraction procedure for speciation of heavy metals, proposed by the Commission of the European Communities Bureau of Reference (BCR), has been applied to a freshwater sediment collected from the River Clyde, Lanarkshire, UK.

TL;DR: In this article, Salicylaldoxime (SA) was used to detect copper complexing ligands in sea water using cathodic stripping voltammetry (CSV) at a detection window intermediate to that and overlapping with those currently available using other electroactive ligands.

TL;DR: In this article, Daunomycin was found to be electrochemically active through voltammetric experiments and was able to distinguish between double and single stranded DNAs using linear sweep voltammetry.

TL;DR: A three-stage sequential extraction procedure, following a protocol proposed by a European working group coordinated and supported by the Community Bureau of Reference (BCR), has been applied to two river sediments from an industrial region of East Catalonia, Spain this paper.

TL;DR: The toxicity and essential nature of Se in the environment depend on its concentration and the chemical forms in which it is present as discussed by the authors, and sensitive analytical methods are required for their determination in complex environmental matrices.

TL;DR: In this paper, a comparative study involving a genetic algorithm, simulated annealing, and stepwise elimination, as methods for wavelength selection in multi-component analysis is presented, where the wavelength selection criteria used are the selectivity and accuracy after Lorber, and the minimal mean squared error after Sasaki.

TL;DR: In this article, a variety of 55 different plasticizers based on various structural elements were investigated in respect to their applicability in liquid polymeric membranes of chemical sensors, and the overall performance of the membrane was judged in relation to the properties of lipophilicity, solubility, exudation and selectivity, respectively.

TL;DR: In this article, the authors examined specificity by analysing individual mineral phases previously equilibrated with metal-spiked artificial sea water and then sequentially extracted according to the three-step BCR procedure.

TL;DR: In this article, the analytical chemistry of the nutrient elements carbon, phosphorus, nitrogen and silicon in environmental waters is discussed and the terminology used for classification is described; the analytical approach is considered in general terms, with particular regard to sample collection and preservation, sample treatment and methods of analysis.

TL;DR: A covalently immobilized oligormers were able to hybridize with available complementary ssDNA (cDNA) which was introduced into the local environmnet to forum double stranded DNA (dsDNA), resulting in an intrinsic mode optical sensor.

TL;DR: In this paper, the average concentrations of ammonium ion and lactate were measured in sweat induced by exhaustive exercise were 115.8 and 90.5 mM respectively, 5.2 and 10.6 times higher than the results obtained from heat induced sweat.

TL;DR: In this article, an improved method was developed for the decontamination of Greenland and Antarctic snow or ice cores for heavy metal analysis, where the investigated core sections are chiselled while being held horizontal in a polyethylene lathe inside a laminar flow clean bench.

TL;DR: In this article, reactive azo dyes are described which are useful for optical determination of pH, which are covalently linked via ethylsulfonyl groups to a novel type of transparent solid films consisting of a thin film of cellulose on top of a polyester support.

TL;DR: In this paper, the enzyme is entrapped in a lipid matrix (cubic liquid crystalline phase) and the cubic phases were made of monoolein (1-monooleyl-glycerol) and 35% (w/w) of water-based enzyme solutions.

TL;DR: In this paper, a 0.75 M solution of the macrocyclic polyether bis-4,4′(5′)-[tert.-butylcyclohexano]-18-crown-6 in isodecanol supported on an inert, polymeric substrate for the separation and preconcentration of lead from acidic media is described.

TL;DR: In this paper, a set of experiments on the complexation of cadmium and lead with humic acids were performed at pH 5.0 using normal and reverse-pulse polarography and d.c. voltammetry.

TL;DR: A flow injection on-line sorbent extraction system was studied in conjunction with flame atomic absorption spectrometry to determine cadmium, copper and lead in digest solutions of solid environmental samples using octadecyl functional groups (C18) bonded silica gel as sorbent with diethylammonium-N,N-diethyldithiocarbamate (DDDC) or ammonium diethylditiophosphate (DDPA) as complexing agent and methanol as eluent as discussed by the authors.

TL;DR: For the applied classification problem Kohonen learning is superior to the back-propagation of errors and the levels of weights in the Kohonen neural network can be exploited to give more detailed information about the separation ability of each individual variable.

TL;DR: In this paper, a simple formalism for the quantitative description of the upper and lower detection limit of pH selective solvent polymeric membrane electrodes containing a neutral carrier and a lipophilic anionic additive is presented, based on the consideration of phase transfer equilibria at the sample/membrane interface.

TL;DR: Transfer of calibration models between near-infrared spectrometric instruments using three different standardisation sets is described and Shenk's algorithm is used for standardisation.

TL;DR: In this article, the authors compared the performance of solid phase extraction (SPE), membrane-SPE and salting-out solvent extraction (SOE) with a set of 58 groundwater samples from an explosives-contaminated military facility.

TL;DR: In this article, the use of in-line UV-digestion for breakdown of dissolved organic matter (DOM), prior to voltammetric determination of trace metals in natural samples, is discussed.

TL;DR: In this article, a solgel derived indicator ceramic carbon electrodes (CCEs) made of graphite powder entrapped in hydrophobically modified silica gel are presented.

TL;DR: In this paper, the authors used the Cascodic stripping square wave voltammetry to detect H2S in sea water over a wide range of concentrations (nM to mM) and found that the addition of metal ions to the solutions was found to depress the signal.

TL;DR: In this article, the determination of organophosphorus and carbamate pesticides was carried out using an amperometric transducer based on a robust, polishable and easily mechinable biocomposite.

TL;DR: In this article, a di-and tetrathioamide functionalized calix arene as ionophores were used as lead selective electrodes and the Pb(II)-response functions exhibited almost theoretical Nernstian slopes in the activity range 10?6?10?2M of lead ions.