Mathematical modeling of a Nafion membrane based optode incorporating 1-(2'-pyridylazo)-2-naphthol under flow injection conditions.

A general mathematical model of a flow-through optical chemical sensor prepared by the immobilization of 1-(2'-pyridylazo)-2-naphthol (PAN) into a commercial Nafion membrane was developed. The model takes into account the preparation of the optode membrane and in our opinion the most important chemical and physical processes involved in the generation of the analytical signal. The following model parameters were determined separately from the experimental verification of the model: aqueous diffusion coefficient of CuSO(4) - 8.

Determination of arsenic in industrial samples by pervaporation flow injection with amperometric detection.

This paper describes a simple and inexpensive pervaporation flow injection (PFI) system for the on-line determination of arsenic in industrial samples based on amperometric detection. The PFI system uses on-line hydride generation for the separation of As(III) from the sample matrix thus substantially reducing matrix interferences associated with "dirty" industrial samples. A method for the speciation of As(III) and As(V) is also described.

On-line determination of mercury(II) by membrane separation flow injection analysis.

A rapid and inexpensive gas-diffusion (GD) flow injection method for the on-line determination of Hg(II) in aqueous samples is described. The analytical procedure involves the injection of a Hg(II) sample into a 1.5M H(2)SO(4) carrier stream which is merged with a reagent stream containing 0.

Determination of carbon dioxide in gaseous samples by gas diffusion-flow injection.

A gas diffusion-flow injection system was developed for the determination of carbon dioxide in gaseous samples. The calibration was based on the use of either gaseous carbon dioxide or aqueous sodium carbonate standards. Gaseous carbon dioxide samples and gaseous or aqueous standards were injected directly into a donor stream of 1.

Determination of ammonia in beers by pervaporation flow injection analysis and spectrophotometric detection.

A pervaporation flow injection (PFI) method is described for the determination of ammonia in beers. After injecting the sample into a NaOH donor solution, ammonia and other volatiles are transferred in the pervaporation unit from the donor stream to an acceptor stream containing sodium salicylate and nitroprusside, which subsequently mixes with alkaline sodium dichloroisocyanurate to allow the classical Berthelot reaction to take place. The blue-coloured complex formed is monitored spectrophotometrically at 655 nm.

Thin layer distillation for matrix isolation in flow analysis.

Analyte transfer from the matrix in a thin layer distillation (TLD) cell and its subsequent measurement were investigated in a flow injection configuration. We designed the cell such that the donor and acceptor streams flowed in parallel channels separated by a thin dividing wall. The matrix transfer process involved room-temperature distillation of the analyte into the headspace of the TLD cell and its subsequent condensation/uptake by a concurrently flowing acceptor stream.

Electrochemical, spectroscopic, structural, and magnetic characterization of the reduced and protonated alpha-Dawson anions in [Fe(eta(5)-C(5)Me(5))(2)](5)[HS(2)Mo(18)O(62)].3HCONMe(2).2Et(2)O and [NBu(4)](5)[HS(2)Mo(18)O(62)].2H(2)O(1).

Reaction of excess Fe(cp)(2) (cp = eta(5)-C(5)Me(5)) dissolved in Et(2)O with [NHex(4)](4)[S(2)Mo(18)O(62)] in acetonitrile, followed by recrystallization of the precipitated solid from N,N'-dimethylformamide (DMF), leads to isolation of the complex [Fe(cp)(2)](5)[HS(2)Mo(18)O(62)].3DMF.2Et(2)O.