The 9-cyano-10-methylacridinium cation possesses an electrophilic center at the carbon atom in position (9) susceptible to the addition of anions. The addition of OOH(-) to this cation--in weakly acidic, neutral, or alkaline media--initiates processes leading to the formation of electronically excited 10-methyl-9-acridinone, which deactivates by light emission. The effect of changes in reactant concentrations and pH on emission decay with time, as well as other features of the accompanying chemiluminescence, were established. Calculations carried out at the semiempirical and density functional theory level demonstrated that initial addition of OOH(-) and subsequent processes lead either to the elimination of OCNH (in weakly acidic and neutral media) or OCN(-) (in alkaline media) and that their exothermicity is sufficiently high to generate electronically excited 10-methyl-9-acridinone. On the other hand, primary addition of OH(-) to C(9) in alkaline media initiates the conversion of the cation to the nonexcited 10-methyl-9-acridinone. This relatively rapid process influences to a substantial extent the intensity of the chemiluminescence. The prospects for the analytical application of 9-cyano-10-methylacridinium salts are briefly outlined.
The sorption properties of Transcarpathian clinoptilolite towards Nd(III) and Gd(III) under dynamic condition have been studied. Nd(III) was sorbed with the best efficiency on the uncalcined clinoptilolite samples from the solutions at pH 6.5. Clinoptilolite samples that were previously calcined at 250 • C exhibit the maximal sorption capacity towards Gd(III) from the solutions at pH 9.5. Nd(III) and Gd(III) sorption on clinoptilolite mechanisms are different: Nd(III) is sorbed according to the ion-exchange mechanism, and the sorption of Gd(III) is carried out mainly by means of the adsorption of soluble hydrolyzed forms of Gd(III) on the zeolite surface. The differences in sorption mechanisms of these lanthanides give an opportunity to separate Nd(III) and Gd(III) from the solutions at pH 9.5. The maximal sorption capacity of the clinoptilolite regarding Nd(III) and Gd(III) at the optimal conditions was found to be 1810 and 6500 µg/g. The best desorbent of Nd from the clinoptilolite is 7 M HNO3 solution. The best desorbent of Gd is 1 M solution of KCl acidified to pH 2.6, which provides a 100% withdrawal of Gd from the zeolite matrix. Transcarpathian clinoptilolite is proposed as a sorbent for the preconcentration of trace amounts of Nd(III) and Gd(III) from aqueous solutions in a solid phase extraction mode.
The interaction of Ru(IV) ions with a novel analytical reagent-5-hydroxyimino-4-imino-1,3-thiazolidin-2-one, by spectrophotometric method was investigated. The complex is formed at pH 5.0 in acetate buffer medium after heating in the boiling water bath (~371 K) for 25 min. The complex has maximum absorption at 350 nm and is stable for 24 h. Beer's law is valid over the concentration range of 0.5-6.1 µg mL-1 for Ru(IV). The molar absorptivity at λ = 350 nm is 6.21 × 10 3 L mol-1 cm-1. The limit of detection of this method is 0.2 µg mL-1. The interfering effect of various cations and anions on the spectrophotometric determination of the Ru(IV) were investigated. The proposed method was successfully applied to the determination of Ru(IV) in alloys.
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