Simultaneous Determination of Nickel and Cobalt as Chelates with 1-(2-Pyridylazo)-2-naphthol Using an LC Switching Column Method

A simple liquid chromatographic method was developed for the separation and simultaneous determination of cobalt and nickel as chelates with 1-(2-pyridylazo)-2-naphthol (PAN). The method, using a switching column technique for the on-line purification and separation, enables to reach the sub-microgram per litre concentration level excluding off-line sample treatment with the exception of the derivatization reaction. Two small-sized columns packed with CN- and C₄-bonded stationary phases were selected and used considering their complementary behaviour with respect to chelated Co and Ni ions. The analysis was performed within 10 min using an optimised eluent (water–acetonitrile–methanol–tetrahydrofuran, 40:45:10:5, v/v/v/v) containing Tween 40 (10^?3 M) and acetate buffer (5 × 10^?3 M, pH 4.8). Detection was performed by UV-vis spectrophotometry (λ = 565 nm) permitting to reach quantification limits of 0.9 and 0.5 μg L^?1 for Co and Ni, respectively.     

A Novel Fibrous Material Created by Self‐Rolling of a Patterned Polymer Thin Film

A new kind of a fibrous material is produced by controlled self‐rolling of patterned thin poly(4‐vinyl)pyridine films in acidic water. Self‐rolling is induced by unequal swelling of the top and the bottom layers of the films in the solvent. Rolling starts from parallel scratches in the film and results in twin‐scroll fibers. The fibers are stabilized by staining with CuCl₂ salt and freeze‐dried. The output of the fiber material production is of the order of 1 cm³ from approximately 50 cm² of the patterned polymer film. The approach opens new broad opportunities for creation of smart fibrous materials via loading the fibers with functional micro‐ and nanoparticles.     

Simultaneous Determination of Nickel and Cobalt as Chelates with 1-(2-Pyridylazo)-2-naphthol Using an LC Switching Column Method

A simple liquid chromatographic method was developed for the separation and simultaneous determination of cobalt and nickel as chelates with 1-(2-pyridylazo)-2-naphthol (PAN). The method, using a switching column technique for the on-line purification and separation, enables to reach the sub-microgram per litre concentration level excluding off-line sample treatment with the exception of the derivatization reaction. Two small-sized columns packed with CN- and C₄-bonded stationary phases were selected and used considering their complementary behaviour with respect to chelated Co and Ni ions. The analysis was performed within 10 min using an optimised eluent (water–acetonitrile–methanol–tetrahydrofuran, 40:45:10:5, v/v/v/v) containing Tween 40 (10⁻³ M) and acetate buffer (5 × 10⁻³ M, pH 4.8). Detection was performed by UV-vis spectrophotometry (λ = 565 nm) permitting to reach quantification limits of 0.9 and 0.5 μg L⁻¹ for Co and Ni, respectively.