Substitutional complexometric determination of magnesium in homogeneous water-dioxan medium, based on decomposition of MgEDTA with 8-quinolinol and titration of released EDTA with calcium. 
A method based on a substitution reaction between MgEDTA and 8-quinolinol, and titration of the liberated EDTA with calcium is proposed.  The reaction is performed in homogeneous 50%-60% dioxan medium at ph 10, in which magnesium forms a soluble and stable 8-quinolinol complex.