Spectrophotometric study of the interaction of some hydroxyanthraquinones (HAQs) with magnesium(II) in a cationic micelle.

Abstract Six different hydroxyanthraquinones (HAQs) in aqueous micellar (cationic, anionic and non-ionic) media were tested as effective and selective chelators for the MgII ion in alkaline conditions. Of these 1,4 and 1,8-dihydroxyanthraquinones were found to effectively bind to MgII ions and were useful for the ppm level spectral determination of MgII ion. The MgII ion forms 1 : 1 and 1 : 2 chelates with 1,4-and 1,8-dihydroxyanthraquinones, respectively, which have maximum absorption at 610 and 575 nm, respectively. MgII can be determined in the presence of a large excess of foreign ions including the CaII ion. The statistical analysis of the results, apparent p K a , expected bathchromic shift of the reagent absorption, molar absorptivity change and electronic spectra in various organized media are discussed.