Calcium complexing dyes and their use in analytical compositions, elements and methods

Abstract From the Canadian patent

Abstract of the Disclosure, Novel chromogenic derivatives of 1,2-bis- (o-aminoaryloxy)ethane-N,N,N',N'-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.