the interaction between eriochrome black t and li , na , k ,mg and ca ions in acetone and dimethylsulphoxide solutions has been investigated spectrophotometrically. the formation constants of the resulting 1 : 1 complexes were determined and found to decrease in the order mg >ca >li >k >na in both solvents used. there is an inverse relationship between the stabilities of the complexes and the s...