The reaction between phenothiazine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in the presence of p-toluenesulfonic acid in chloroform was investigated by potentiometry, voltammetry and spectrophotometry, and the reaction pathways were proposed. The conditions for the oxidimetric titration of phenothiazines with a standard chloroform solution of DDQ were optimized and the potentiometric...

The formation of complexes of Zn(II), Cd(II), Hg(II), and Pb(II) and N -carboxymethylD,L-threonine (H2CMT, H2L) in aqueous solutions has been studied by spectrophotometric and potentiometric methods. The complexation model for each system has been established by the HYPERQUAD program from the potentiometric data. Three different behaviors are found: ML2H, MLH, ML, MLOH, and ML2 complexes are fo...

A thiocyanate poly(vinyl chloride) (PVC) membrane electrode based on [1,2-bis(diphenylphosphino)ethane]dihalopalladium(II), [(dppe)PdX2, X = Cl (L), X = I (L)] as active sensor has been developed. The diiodopalladium complex, [(dppe)PdI2](L) displays an anti-Hofmeister selectivity sequence: SCN‒ > I‒ > ClO4‒ > Sal‒ > Br‒ > NO2‒ > HPO4‒ > AcO‒ > NO3‒ > H2PO4‒ > CO32‒. The electrode exhibits a Ne...

This article is focused on the determination of lidocaine hydrochloride as a local anaesthetic drug. A potentiometric method based on modified screen-printed and modified carbon paste ion-selective electrodes was described for the determination of lidocaine hydrochloride in different pharmaceutical preparations. It was based on potentiometric titration of lidocaine hydrochloride using modified ...

This article is focused on the determination of lidocaine hydrochloride as a local anaesthetic drug. A potentiometric method based on modified screen-printed and modified carbon paste ion-selective electrodes was described for the determination of lidocaine hydrochloride in different pharmaceutical preparations. It was based on potentiometric titration of lidocaine hydrochloride using modified ...

Measurement of the decrease in pH that accompanies the addition of Zn2+ to heparin in solution provided an indirect method of examining cation-polyanion interaction. Construction of plots analogous to isothermal saturation binding plots revealed the existence, for defined conditions of interaction, of a [heparin]-independent direct proportionality between the fraction of the maximal pH change o...

A convenient reference cell and method of potentiometric determination of chloride ions with silver nitrate is described. The method is accurate to about +/- 0.02 ml. 10(-4)M silver nitrate.

A PVC-membrane electrode based on a recently synthesized 18-membered macrocyclic diamide is presented. The electrode reveals a Nernstian potentiometric response for Co2+ over a wide concentration range (2.0 x 10(-6)-1.0 x 10(-2) M). The electrode has a response time of about 10 s and can be used for at least 2 months without any divergence. The proposed sensor revealed very good selectivities f...

We have examined the redox behavior of the cytochrome c1aa3 complex from Thermus thermophilus. In potentiometric titrations the cytochrome c behaves as an independent center having n = 1 and E = 205 mV (NHE). Under the assumption that the individual centers equilibrate independently in this experiment, changes in the absorption band at 603 nm have been resolved into two components: cytochrome a...

EPR-based potentiometric titrations are a well-established method for determining the reduction potentials of cofactors in large and complex proteins with at least one EPR-active state. However, such titrations require large amounts of protein. Here, we report a new method that requires an order of magnitude less protein than previously described methods, and that provides EPR samples suitable ...