Lead is environmental pollutant that even in low trace is harmful for human health and wildlife. In this study we presented a colorimetric method for determination of Pb2+ in water by aggregation of silver nanoparticles capped citrate in the presence of deferoxamine as chelating agent. Silver nanoparticles were prepared by reduction of AgNO3 with NaBH4. In the presence of Pb2+, mixture of silver nanoparticles capped citrate and deferoxamine aggregated and color of solution changed from light yellow to violet that depends on Pb2+ concentration. As a result of aggregation, local surface plasmon resonance (LSPR) band of silver nanoparticles around 440 nm decreases and a new band appears at 580 nm that depend on Pb2+ concentration. Under optimized conditions, linear relation of concentration of Pb2+ and absorbance ratio (A580/A440), was from 0.19 to 1.29 µmol L-1 and limit of detection of 0.056 µmol L-1 was found. Control experiments with the addition of 10 other metal ions (Ni2+, Cu2+, Ca2+, Al3+, Co2+, K+, Ba2+, Zn2+, Mg2+, Hg2+) did not result in a distinct change in the color or in the absorption spectra. This approach was successfully tested for determination of Pb2+ in well and tap water.

The electrocatalytic oxidation of unsymmetrical dimethylhydrazine (UDMH) has been studied on a Prussian Blue modified carbon paste electrode (PBMCPE) by cyclic voltammetry technique. The results show that Prussian Blue acts as a suitable modifier for electron transfer in the oxidation of UDMH. A linear range of 3 × 10-5 to 1.15 × 10-3 mol L-1, with a limit of detection (3σ) of 1.6 × 10-5 mol L-1 was obtained using the amperometric method. The proposed sensor exhibited several advantages, including, namely, no interference from hydrazine, simple preparation, good stability and repeatability. Finally, the PBMCPE was successfully applied for determination of UDMH in water samples.

A redução eletroquímica do agente anestésico inalatório isoflurano foi estudada em eletrodo de carbono vítreo na presença de cloreto de tetrafenil porfirinaferro(III) (Fe(TPP)Cl) em solução de dimetil sulfóxido (DMSO). A capacidade da Fe(TPP)Cl como potencial catalisador homogêneo para a redução de isoflurano foi testada por voltametria cíclica e cronomperometria. Revelou-se a excelente capacidade eletrocatalítica para a redução de isoflurano com sobrepotential de aproximadamente 1150 mV mais positivo do que o potencial observado para redução de isoflurano em solução de DMSO. Uma faixa linear entre 3,0 × 10-5 e 2,1 × 10-4 mol L-1 para a determinação de isoflurano em solução de DMSO contendo Fe(TPP)Cl foi obtida de medições de voltametria cíclica. Estimou-se o limite de detecção em 1,8 × 10-5 mol L-1. Um possível mecanismo catalítico é proposto.

The electrochemical reduction of the inhalational anesthetic agent isoflurane was studied at glassy carbon electrode in presence of iron(III) tetraphenylporphyrin chloride (Fe(TPP)Cl) in dimethyl sulfoxide (DMSO) solution. The ability of Fe(TPP)Cl as potential homogenous catalyst for the reduction of isoflurane was tested by cyclic voltammetry and chronomperometry. It showed excellent electrocatalytic ability for the reduction of isoflurane with overpotential of about 1150 mV more positive than the potential for observed reduction of isoflurane in DMSO solution. A linear range between 3.0 × 10-5 and 2.1 × 10-4 mol L-1 for the determination of isoflurane in DMSO solution containing 0.04 mmol L-1 Fe(TPP)Cl was obtained from cyclic voltammetry measurements. The limit of detection was estimated at 1.8 × 10-5 mol L-1. A possible catalytic mechanism is proposed.