BT

2-Hydroxy-1-(1-hydroxy-2-naphthylazo)-6-nitro-4-naphthalenesulfonic acid, sodium salt. Application: Metal indicator, Ca2+ and Mg2+ detection, colorimetric.


BT in aqueous solution changes color according to pH: red at pH<6, blue at pH 7-11, and orange at pH>12. Its proton dissociation constants are reported to be pKa2=6.3 and pKa3=11.55 (m=0.08, 20ºC). BT is one of the most commonly used indicators of Ca, Mg, Zn, Cd, Pb, Hg, and rare earth metals for EDTA chelate titration. BT solution turns red in the presence of the metals at pH 10, and then changes to blue at the endpoint of the titration.

BT
DJB015
25 g