| abstract |
Novel chromogenic derivatives of 1,2-bis( 0 -aminoaryloxy)ethane-N,N,Nʹ,Nʹ-tetraacetic acid are useful for the determination of calcium ions in both solution and dry assays. These compounds comprise a dye moiety which is directly conjugated to the acetic acid substituted-nitrogen atom and which enables the compounds to exhibit maximum absorbance at a wavelength generally greater than 400 nm before complexation. When the compounds are complexed with calcium ions, the absorbance shifts to a shorter wavelength. |