ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Spectrophotometric Determination of Magnesium, Calcium, Strontium and Barium Present in Pairs by Use of Tetramethylmurexide

R. Kohn

Institute of Chemistry, Slovak Academy of Sciences, Bratislava 9

Abstract:  A spectre-photometric method is described for the determination of magnesium, calcium, strontium and barium coexisting in binary mixtures. The method employs totramethyimurexide as an auxiliary ligand, and has been developed for pure two-component systems, such as are involved in investigations of cation-exchange equilibria on anionic polymers. The analysis is performed with calibration curves of the φ = f[Me(I), Me(II)], where φ   is the ratio of two absorbances А₁ and A₂ measured at two suitable wavelengths, λ₁ and λ₂. The wavelengths λ₁ and λ₂ are chosen from the absorption spectra of solutions containing the separate metals Me(I) or Me(II). The absorption spectra of solutions containing the tetramethylmurexide complexes of Ca²⁺, Sr²⁺ or Ba²⁺ ions are independent of the identity of the anions present in the system (Cl^-, NO₃^- and CH₃COO^-). The results show that two arbitrarily chosen elements of the alkaline earths can be determined with a good accuracy in the presence of each other over a large concentration range (0.001 —0.05 м). Calcium, strontium and barium can bo estimated with high accuracy in solutions containing a considerable excess of either magnesium or potassium, this exceeding the concentrations of the above alkaline-earth elements by factors of 100, 50 and 20, respectively. Calcium can also be estimated with barium or strontium present in a 30-fold or a 20-fold molar excess, respectively.

Full paper in Portable Document Format: 2310a721.pdf

Chemical Papers 23 (10) 721–735 (1969)