Coated,Wire-Based,New Schiff Base Potentiometric Sensor for Lead(II) Ion

An ion-selective electrode for lead(II) based on a dispersion of N,N"-bis(3-methyl salicylidine)-p-phenyl methane diamine particles into a polymeric membrane using coated-wire configuration is described. Membranes based on polyvinyl chloride containing different amounts of plasticizer and ionophore are studied. The best performance in terms of slope (30.3 ± 0.6 mV per decade) and response time (<15 s) is displayed. The sensor shows a Nernstian response for Pb(II) ions over a wide concentration range of 2.0 × 10^–5 to 0.10 M. The sensors can be used for more than three months without any considerable divergence in potentials. The selectivity is also good towards the most common univalent and divalent cations and the signal is constant in the pH range 1.6–6.0. An application to lead determination in mineral rocks and wastewater proved to be a success, and it was employed as an indicator electrode in potentiometric titration of CrO^2– ₄ with lead ions.     

Novel Coated-Wire Membrane Sensor Based on Bis(Acetylacetonato) Cadmium(II) for the Determination of Chromate Ions

A new electrode based on a complex of chromate ions with bis(acetylacetonato) cadmium(II) as a carrier was developed for detection of chromate in aqueous solution. The electrode exhibited linear response with Nernstian slopes of –28.8±0.5mVper decade for chromate within the concentration range of 2.5×10^–6–0.1M. The limit of detection as determined from the intersection of the extrapolated linear segments of the calibration plots was almost 1.0×10^–6M. The electrodes exhibited good selectivities for chromate. The response time of the electrode was <25s over the entire concentration range. The electrode can be used in the pH range 8.0–12.0 for chromate. It was used as an indicator electrode in titration with Pb(NO₃)₂ and for the determination of chromate ion in wastewater samples.     

Rings with divisibility on chains of ideals

We present a generalization of the ascending and descending chain condition on one-sided ideals by means of divisibility on chains. We say that a ring R satisfies ACC_d on right ideals if in every ascending chain of right ideals of R, each right ideal in the chain, except for a finite number of right ideals, is a left multiple of the following one; that is, each right ideal in the chain, except for a finite number, is divisible by the following one. We study these rings and prove some results about them. Dually, we say that a ring R satisfies DCC_d on right ideals if in every descending chain of right ideals of R, each right ideal in the chain, except for a finite number of right ideals, is divisible by the previous one. We study these conditions on rings, in general and in special cases.