Analytical & Bioanalytical Electrochemistry
Volume:2 Issue: 2, Jun 2010

A new method for simultaneous kinetic-potentiometric determination of Zr(IV) and Fe(III) at trace levels using partial least-square (PLS) and H-point standard addition method (HPSAM) is described. The methods are based on the difference observed between complex reaction rate of Zr(IV) and Fe(III) with fluoride ion. Therefore, the reaction rate of Zr(IV) and Fe(III) with fluoride ion was monitored by a fluoride ion-selective electrode (FISE). Results have demonstrated that the simultaneous determination of Zr(IV) and Fe(III) can be done in the concentration ranges of 0.2 - 20.0 and 0.5 – 40.0 μg mL-1, respectively. The total relative standard error of applying PLS method on 8 synthetic samples in the concentration ranges of 1.0 - 20.0 μg mL-1 of Zr(IV) and 1.0 - 35.0 μg mL-1 of Fe(III) was 1.85. The effects of certain foreign ions, upon the reaction rate, were determined for assessing the selectivity of the method. The proposed methods (HPSAM and PLS) were successfully applied to the simultaneous determination of Zr(IV) and Fe(III) in different water samples.

A simple, low-cost and sensitive method has been used to investigate the interaction between a cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), two anionic dyes, C.I. Direct Orange 26 (DO26) and C.I. Direct Red 16 (DR16), and a drug,Atenolol (ATN). The methods used to study the interaction were electromotive force (EMF) measurements involving a surfactant–selective electrode and spectrophotometry. This method was also used to investigate the interactions of Atenolol (ATN). The interaction between TTAB and DO26 was found to be stronger than that of TTAB and DR16. TTAB only showed a weak interaction with ATN at a high drug concentration. Therefore, when ATN was added to a mixture of TTAB and the dye, ATN was found to first interact with the dye and, when ATN saturated, a higher concentration of TTAB interacted with the dye.

Electrical conductances of aqueous ionic liquids, 1-propyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-pentyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium bromide solutions in dilute region in the presence of amino acid, L-arginine, have been measured at T = 298.15 K. The ion association constants, KA,limiting molar conductivities, 0 and distance parameters, R were obtained using lowconcentration Chemical Model (lcCM) conductivity equation for the investigated ionicliquids. The results show that the KA value and limiting molar conductivity, Λ0 decrease with and lengthening alkyl chain of ionic liquids. Therefore, there is slight ion association effect in [HMIm]Br. This can be attributed to the interaction of [RMIm]Br with the amino acids and increasing viscosity of mixture.

An attempt has been made to develop a highly selective copper ion selective electrode based on a PVC based sensor using Bis(2-chlorobenzaldehyde)phenyl disulphide diimine as ionophore with 61% NPOE in presence of 33.5% PVC,0.5% dithio ligand and 5% STPB as an anion excluder. The sensor exhibits a near Nernestian potential response of 29±1mV/decade. Over a wide concentration range of (5.0×10-6 to 5.0×10-2 mol/L) with a detection limit of 3.1×10-6 M between pH=4-7 with a fast response time of 5s. The selectivity coefficient values, as determined by matched potential method indicate excellent selectivity for Cu2+ over a large number of ions. The proposed sensor exhibit an adequate shelf time (3 months) with good reproducibility. The quantification of Cu2+ in waste water of copper wire manufacturing factory was successfully achieved using the proposed sensor.

Electrocatalytic oxidation of adrenalin was investigated on cooper electrode in alkaline solution. The process of oxidation involved and its kinetics were established by using, chronoamperometry techniques as well as steady state polarization measurements. A mechanism based on the electrochemical generation of CuIII active sites and their subsequent consumption by the adrenalin in question was also investigated.