Binding of Transition Metal Ions by the Calcium Indicator Hydroxy Naphthol Blue

Abstract

It has been found that the calcium indicating azo-dye, hydroxy naphthol blue (HNB), binds more strongly to transition metal ions than to the alkaline earth ions it is currently used for. HNB was found to form 1:1 complexes with all of the metal ions studied, and lower limits of detection for these metals based on spectrophotometric analysis were found to be typically two orders of magnitude lower than those previously reported for alkaline earth ions. Analysis of transition metal ions with hydroxy naphthol blue is found to be highly sastifactory, since most metals can be determined down to the ng/ml level.

Key Words:

• spectrophotometric analysis
• hydroxy naphthol blue
• transition metals