Coated wire ion-selective electrode for palladium(II) and its application to catalyst analysis

A novel optode sensor for the determination of palladium(II) in water and a hydrogenation catalyst

A novel optical sensor was established to determine palladium(II) based on the immobilization of 1-(2-pyridylazo)-2-naphthol (PAN) on a triacetylcellulose membrane. Palladium ions react with the immobilized PAN and cause a decrease in the absorbance of the membrane at 469 nm. The response time of the optode was 8-10 min depending on the concentration of Pd(II) ions. This sensing phase had a dynamic linear range of 0.10-12.0 ?g ml-1 palladium ions with a limit of detection of 65 ng ml-1. The sensor can readily be regenerated using an ethylenediamine solution. The sensor could be fully regenerated, and the color change was fully reversible. The method was successfully applied for the determination of Pd(II) in synthetic aqueous solutions and in a hydrogenation catalyst sample.

Palladium and the electrochemical quartz crystal microbalance: a new method for the in situ analysis of the precious metal in aqueous solutions

A new method for the quantitative determination of palladium(II) by the electrochemical quartz crystal microbalance (EQCM) technique has been developed. Using a bare carbon-coated quartz crystal, Pd(II) ions are directly deposited from aqueous solution as palladium metal onto the crystal surface, and the Pd(II) concentration is determined with a detection limit of 0.0156 mM, or 1.66 ppm. No complexing agent or preconcentration of palladium is required for the analysis. The palladium is stripped from the crystal through its electrochemical oxidation, regenerating the crystal for subsequent multi-cycle palladium analyses. A conventional gold-coated quartz crystal was incapable of carrying out the same measurements. The EQCM technique presented is simple, sensitive, and reproducible for the detection of this widely used precious metal.

Coated Wire Silver-Ion Selective Electrode Based on a N,N′-Bis(2-thienylmethylene)-1,2-diaminobenzene

A novel membrane coated platinum-wire electrode (MCPWE) based on N,N'-bis(2-thienylmethylene)-1,2-diaminobenzene (BTMD) for highly selective determination of Ag+ ion has been developed. The influences of membrane composition and pH on the potentiometric responses of electrode were investigated. The potentiometric responses are independent of the pH of the test solution in the range of 5.0 - 9.0. The electrode shows a linear response for Ag+ ion over the concentration range of 1.0 x 10(-60 to 1.0 x 10(-1) M with a lower detection limit of 6.0 x 10(-7) M. The electrode possesses a Nernstian slope of 59.7 mV decade(-1) and a fast response time of < or = 17 s and can be used for at least 2 months without any observable deviation. The proposed electrode displayed very good selectivity for Ag+ ion with respect to NH4+ and alkali, alkaline earth and some common transition metal ions. The practical utility of the electrode has been demonstrated by its use as the indicator electrode in the potentiometric titration of an AgNO3 solution with a NaI solution and in determination of the silver content of a developed radiological film.