This paper presents a direct algebraic method of searching for analytic solutions of the two-dimensional time-independent Schrödinger equation that is impossible to separate into two one-dimensional ones. As examples, two-dimensional polynomial and Morse-like potentials are discussed. Analytic formulas for the ground state wave functions and the corresponding energies are presented. These results cannot be obtained by another known method.
The present study reviews more than twenty years (1985-present) of published research on the development and application of analytical procedures for the determination of chlorine dioxide, a widely used disinfectant and bleaching agent. The review covers a variety of techniques including batch and automated spectrophotometry and fluorimetry, electroanalysis and chromatography. The analytical figures of merit to the methods are presented, while critical discussion regarding their advantages and disadvantages is addressed. [...]