Anodic polymerization of functionalized 1,4-dialkoxybenzenes: Synthesis of a p-doped polyacidic polyphenylene

1,4-Dialkoxybenzenes can be anodically polymerized into polyphenylenes. The present paper deals with monomers carrying an acidic function, and the preliminary results are compared with those obtained with the relevant anhydride.     

Determination of phosphate in urine by sequential injection analysis

Two simple turbidimetric methods for the determination of phosphate in urine are presented and compared. One method is based on the calcium phosphate crystallisation, and the other one on the inhibitory action of phosphate on the calcium carbonate crystallisation. The analytical features of both methods were: linear range = 0.2-1.5 g L-1, LOD = 14 mg L-1 and RSD 1.1-2.0% for the calcium phosphate method, linear range = 0.1-1.8 mg L-1, LOD = 0.01 mg L-1 and RSD 0.97-1.90% for the inhibitory method. Urines with high calcium content (> or = 400 mg L-1) can interfere the method based on the crystallisation of calcium phosphate. This interference was solved using a cation exchange resin as a part of the manifold. Considering the low toxicity of used reagents, these methods can be considered as a contribution to Green Analytical Chemistry.     

Analytical potential of enzyme-coated capillary reactors in capillary zone electrophoresis

Enzymes immobilized on the inner surface of an electrophoretic capillary were used to increase sensitivity and resolution in capillary zone electrophoresis (CZE). Sensitivity is enhanced by inserting a piece of capillary containing the immobilized enzyme into the main capillary, located before the detector, in order to transform the analyte into a product with a higher absorptivity. This approach was used to determine ethanol. In order to improve resolution, capillary pieces containing immobilized enzymes were inserted at various strategic positions along the electrophoretic capillary. On reaching the enzyme, the analyte was converted into a product with a high electrophoretic mobility, the migration time for which was a function of the position of the enzyme reactor. This approach was applied to the separation and determination of acetaldehyde and pyruvate. Finally, the proposed method was validated with the determination of ethanol, acetaldehyde, and pyruvate in beer and wine samples.     

Characterisation of alkylamine ethoxylates (ANEOs) in commercial herbicide formulations using liquid chromatography/electrospray ionisation mass spectrometry

A quantitative method is described for the characterization of alkylamine ethoxylate (ANEO) surfactants in commercial herbicide formulations using reversed‐phase high‐performance liquid chromatography with electrospray ionization mass spectrometric detection. The proposed protocol allows the simultaneous determination of a full range of oligomers which were monitored as [M–H]⁺ ions in positive ion mode. The instrumental detection limits (LODs) were 0.5 µg. The method developed was successfully applied to the determination of ANEOs in a number of glyphosate formulations. Both the total concentration of these surfactants and the oligomer distribution varied between the different commercial herbicides analysed. The precision of the determination of the oligomers in samples ranged from 0.5 to 15%. Copyright © 2010 John Wiley & Sons, Ltd.     

Gold doped by palladium: Building of Au–Pd electrodes showing exceptional capability for achieving electrocatalytic reductions

Smooth gold is easily palladized by means of very thin galvanostatic deposits of Pd⁰. Such chemically modified materials are mainly tested in acetonitrile in the presence of tetraalkylammonium salts (TBABF₄). All exhibit large usable electrochemical windows: between ? 1.8 V and + 1.5 V vs. saturated calomel electrode (SCE). When employed as cathodic material, they show exceptional catalytic capabilities especially for achieving the one-electron cleavage of organic halides (RX). Thus, these modified surfaces, found to be chemically and electrochemically stable, lead to amazing potential shifts compared to those obtained with glassy carbon, smooth platinum, or gold cathodes under the same experimental conditions. Specifically, these palladium-doped gold interfaces were preliminarily used for the reduction of alkyl iodides RIs. The presence of gold is expected to boost up the catalytic effect of palladium already reported with such compounds.     

Monitoring nanoparticles in the environment

The presence of nanoparticles in the environment can have important implications for both environmental and human health. Nanoscience and nanotechnology are expected to change industrial production and the economy as we know them today. However, nanotechnologies can also be a source of risks. The increasing use of nanoparticles in industrial applications will inevitably lead to the release of such materials into the environment. Accurately assessing the environmental risks posed by nanoparticles requires using effective quantitative analytical methods to determine their mobility, reactivity, ecotoxicity and persistency, many of which have still to be developed. This overview describes some methodological aspects relating to the fields of nanoparticle analysis, nanometrology and analytical chemistry.     

Determination of 2-ethylhexyl 4-(dimethylamino) benzoate using membrane-assisted liquid–liquid extraction and gas chromatography-mass spectrometric detection

A flow-cell for micro-porous membrane liquid–liquid extraction with a sheet membrane was used to extract 2-ethylhexyl 4-(dimethylamino) benzoate (EDB) from urine of solar-cream users and spiked wine samples. The cell enabled the target analyte to be extracted from 7.9 mL of donor solution into 200 μL of acceptor solution (decane). After extraction, the acceptor solution was transferred to a micro-vial for GC-MS analysis without derivation. In this work, variables affecting the enrichment factor were also studied, such as organic solvent, extraction time, recirculation flow of the donor solution through the donor chamber, presence of potassium chloride and ethanol in the donor solution and pH. The method has been evaluated in terms of linearity, sensitivity, precision, limits of detection and quantification and extraction efficiency. Limits of quantification were 1 and 3 μg L⁻¹ EDB for urine and wine, respectively. Quantitative analysis has been carried out by applying the method of standard additions. Within- and between-day relative standard deviations were lower than 12% and 20%, respectively. EDB was found in the urine of users of cream containing EDB in the concentration interval 1.2–7.2 μg L⁻¹. Therefore, this provides evidence of EDB dermal absorption and subsequent excretion through the urinary tract. EDB was not found in the analysed wine samples.     

Use of basic amphiprotic organic solvents containing neutral-surfactant aggregates as pseudostationary phase in non-aqueous capillary electrophoresis

A new approach to non-aqueous capillary electrophoresis based on the addition of anionic carboxylic surfactants to the basic amphiprotic organic solvent in which form neutral-surfactant aggregates was developed with a view to improving the electrophoretic resolution of charged substances. These aggregates acts as a new pseudostationary phase. The presence of these aggregates allows the effective separation of four tetracyclines with increased selectivity. The efficiency of sodium caprylate, sodium laurate and sodium palmitate as surfactants was examined. The latter two proved more effective than the former as they provided migration times reproducible to within 7% or better in all cases. The additional use of an alcohol allows peak shape to be controlled, which expands the potential of this electrophoretic technique even further. The proposed method was used to determine tetracyclines in water samples. The sensitivity of the determination was improved by using a flow manifold coupled at-line to the capillary electrophoresis system in order to preconcentrate the analytes. The limits of detection thus achieved ranged from 50 to 90 μg/l. Under optimal operating conditions, recoveries ranged from 97 to 104%, and precision from 5.4 to 7.0%.