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Humic substances (HS) and other substance of similar nature (“building blocks” of HS, such as salicylates or phthalates) influence strongly a polarographic behaviour of europium at a mercury drop electrode. An addition of these substances into the supporting electrolyte causes an enhancement of the differential pulse polarographic (DPP) peak of Eu and an anodic shift of the maximum peak potential...
We developed a novel copolymer modified amperometric immunosensor for the detection of cholera antitoxin (anti-CT), by the electropolymerization of pyrrole–biotin and pyrrole–lactitobionamide monomers on platinum or glassy carbon electrodes. In the detection of cholera antitoxin we have used three enzymatic marker detection systems based on HRP-labeled rabbit IgG antibodies, biotinylated polyphenol-oxidase...
Titanium oxide/phenylphosphonate hybrids were prepared by a two-step sol–gel processing, in the presence of ferrocenylphosphonic acid as an electrochemical probe. We showed that as expected the diffusion of the redox species was related to the kinetics of the sol–gel polymerization. The probable passage through cluster Ti 4 O(O i Pr) 8 (PhPO 3 ) 3 has been confirmed...
The roles of chemical kinetics and mass transfer in three types of bioreactors (packed-column reactors, rotating disk bioreactors and amperometric detector), used with continuous-flow sample/reagent(s) processing, are discussed in detail. A normalized quantitative comparison between these types of reactors clearly shows that rotating disk reactors afford a significantly more efficient utilization...
The supramolecular complexing properties of cyclodextrins (CDs) have been investigated inside a conducting polymer environment. In this work, we report the synthesis and characterization of a polypyrrole/β-cyclodextrin (Ppy/β-CD) film at a glassy carbon (GC) electrode surface. The polypyrrole/β-cyclodextrin (Ppy/β-CD) film was prepared by a simple electropolymerization of a 20:1 mixture of the CD...
In this work, Amberlite XAD-2 resin functionalized with 4,5-dihydroxy-1,3-benzenedisulfonic acid was synthesized, characterized and applied as a new packing material for an on-line system to nickel preconcentration. The method is based on the sorption of Ni(II) ions in a minicolumn containing the synthesized resin, posterior desorption using an acid solution and measurement of the nickel by spectrophotometry...
The efficiency of niobium(V) oxide as a sorbent phase for solid phase microextraction (SPME) was investigated. The thin glass–ceramic rod was coated with niobium(V) oxide using chemical vapor deposition and Nb 2 O 5 as a chemical precursor. Optimum conditions for the preparation and conditioning of the fibers are presented. The fibers were used for the extraction of a mixture of alcohols...
A new sequential injection spectrophotometric method was proposed for the determination of metoclopramide and tetracaine hydrochloride. The method was based on the detection of an unstable red intermediate compound resulting from the reaction of metoclopramide or tetracaine hydrochloride with potassium dichromate, in the presence of sodium oxalate, in sulfuric acid solution. The related reaction mechanisms...
In this paper, a new high sensitivity potentiometric pH-electrode with a response in the acid region is proposed. It consists of a PbO 2 –paraffin matrix deposited on graphite. Its simple construction and studies of some variables at 0.5molL −1 ionic strength are reported. A direct relationship between the electric potential difference and the solution pH was observed for pH values...
A micellar solution of sodium dodecylsulfate (SDS) exhibits the property of being separated into two phases due to a temperature change or the addition of salts. The ammine-complexes of copper(II), nickel(II) and palladium(II) reacted with the dodecylsulfate anion to form the corresponding ion-pair, and were extracted into the SDS gel phase. The SDS plays the roles of a pairing-ion for the ammine-complexes...
Prediction of the optimal extraction solvent based on the solubility parameter to extract the typical organochlorine pesticides from Jiangxi red soil was reported in this paper. Hildebrand solubility parameters, including dispersion coefficient (δ d ), polarity (δ p ) and hydrogen bonding (δ h ), of extraction solvents (including hexane, dichloromethane, hexane/methanol (4:1,...
The sorptive potential of sunflower stem (180–300μm) for Cr(III) ions has been investigated in detail. The maximum sorption (≥85%) of Cr(III) ions (70.2μM) has been accomplished using 30mg of high density sunflower stem in 10min from 0.001M nitric and 0.0001M hydrochloric acid solutions. The accumulation of Cr(III) ions on the sorbent follows Dubinin–Radushkevich (D–R), Freundlich and Langmuir isotherms...
A study of the statistic characteristics of the multidetermination of several enological parameters – namely, alcoholic degree, volumic mass, total acidity, glycerol, total polyphenol index, lactic acid and total sulphur dioxide – depending on the spectroscopic zone employed, was carried out. The two techniques used were near infrared spectroscopy (NIRS) and Fourier transform mid infrared spectroscopy...
Two procedures are proposed in this work for the determination of methanol impurities in o,o-dimethyldithiophosphoric acid (DMDTPA). To avoid possible interferences from the main component, DMDTPA was precipitated in the form of insoluble lead complex. Free Pb(II) ions were eliminated with sulfuric acid and methanol was oxidized to formaldehyde with potassium permanganate in methanesulfonic acid medium...
Non-negative matrix factorization (NMF), with the constraints of non-negativity, has been recently proposed for multi-variate data analysis. Because it allows only additive, not subtractive, combinations of the original data, NMF is capable of producing region or parts-based representation of objects. It has been used for image analysis and text processing. Unlike PCA, the resolutions of NMF are non-negative...
A chitosan resin derivatized with N-methyl-d-glucamine (CCTS-NMDG) was synthesized by using a cross-linked chitosan (CCTS) as base material. The N-methyl-d-glucamine (NMDG) moiety was attached to the amino group of CCTS through the arm of chloromethyloxirane. The adsorption behavior of 59 elements on the synthesized resin was systematically examined by using the resin packed in a mini-column, passing...
The microwave-assisted acid-digestion for the determination of metals in coal by ICP-AES was investigated, especially focusing on the necessity of adding HF. By testing five certified reference materials, BCR-180, BCR-040, NIST-1632b, NIST-1632c, and SARM-20, it was found that the two-stage digestion without HF (HNO 3 +H 2 O 2 was used) was very effective for the pretreatment...
HS-SPME–GC–MS in combination with PCA was employed to discriminate different arabica/robusta blends having different geographical origins. HS-SPME confirmed to be an effective and reproducible sampling technique for routine characterization of coffees. In addition, the chemometric approach permitted to find parameters suitable for the differentiation of the different blends and the determination of...
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