C HITOSAN/ Gelatin/2-(Dimethylamino) ethyl methacrylate (Cs/Gltn/PDMAEMA) hydrogel was synthesized by gamma irradiation for the expulsion of phosphate ions from wastewater. Chemical adjustment of the hydrogel with thiourea was performed to introduce thiol groups Cs/Gltn/PDMAEMA-treated. Moreover trapping of SiO 2 into the hydrogel matrix to acquire Cs/Gltn/PDMAEMA/SiO 2 composite. It was found that the gelation increases with increasing PDMAEMA content in the hydrogel. The maximum gelation performed at an equal ratio of Cs/Gltn at a radiation dose of 15 kGy. The adsorption capacities of the prepared systems towards phosphate ions were investigated. It was obtained that the maximum removal is achieved at pH 6 through 180 min. However, the removal percent decreases with increasing phosphate ions concentration and temperature. The ability of the prepared adsorbents towards phosphate ions removal are ascending ordered in the sequence of Cs/Gltn/PDMAEMA hydrogel, Cs/Gltn/PDMAEMA-treated , and Cs/Gltn/PDMAEMA/SiO 2 composite. The pseudo secondorder equation fits well the adsorption kinetics. The adsorption isotherm follows the Freundlich model higher than the Langmuir model

Novel sensitive disposable sensors have been introduced for potentiometric determination of naproxen (NAP) based on single‐walled carbon nanotubes‐polyvinyl chloride (SWNTs‐PVC) composite incorporated of calix[4]arene as host‐guest molecular recognition element. The electrode matrix composition was optimized on the basis of the nature and content of the sensing element, cationic sites, plasticizer and nanomaterial. Remarkable selectivity and sensitivity towards NAP was achieved in the concentration range from 10−8 to 10−2 mol L−1 with anionic Nernstian compliance −61.0±0.0 mV decade−1. Modification with calixarene and carbon nanotubes improved the sensors performance through formation of NAP‐calixarene inclusion complex and promotion of the electron‐transfer processes which enhance the potential stability, response time, and shelf lifetime of the sensor. The proposed sensors were successfully applied for the potentiometric assay of NAP in dosage formulation and biological fluids under batch and flow injection analysis (FIA) conditions with average recoveries agreeable with the reported official methods.

The interaction of trimethyltin(IV) with N,N,N',N'-tetraethylethylenediamine (Et 4 en) was investigated potentiometrically. The hydrolysis constants of trimethyltin(IV) species and formation constants of the amine complexes are determined. The formation constant of the complex is high, which may suggest to use Et 4 en as an antidote for triorganotin(IV) poisoning, the main source of marine environmental pollution. The effect of solvent dielectric constant of the medium and temperature on the complex formation equilibria was investigated.

Binary and ternary complexes of Cu 2+ involving pyridine-2-carboxylic acid (picolinic acid; PA) and amino acids, peptides or DNA constituents(HL) have been investigated. Ternary complexes of amino acids or peptides are formed by simultaneous reactions. Amino acids form the [Cu(PA)L] complex, whereas peptides form [Cu(PA)L] and [Cu(PA)(LH -1 )]. The ternary complexes of Cu 2+ with picolinic acid and DNA are formed in a stepwise process, whereby binding of Cu 2+ to picolinic acid is followed by ligation of the DNA constituents. The stability of the ternary complexes is compared with the stabilities of the corresponding binary complexes. DNA constituents form both 1:1 and 1:2 complexes with[Cu(PA)] + . The concentration distribution of the complexes in solution was evaluated. Probable mode of chelation with picolinic acid and various biologically relevant ligands was discussed. Absorption spectra of the binary and ternary complexes of Cu 2+ were also investigated. The isolated metal chelates, [Cu(PA)(Cl2)(H2O)2] and [Cu(PA)2(Cl2)], are characterized by elemental analysis and infrared measurements.

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