Pontachrome Blue-Black

Fluorimetry is generally used if there is no colorimetric method sufficiently sensitive or selective for the substance to be determined. In inorganic analysis the most frequent applications are for the determination of metal ions as fluorescent organic complexes. Many of the complexes of oxine fluoresce strongly aluminium, zinc, magnesium, and gallium are sometimes determined at low concentrations by this method. Aluminium forms fluorescent complexes with the dyestuff eriochrome blue black RC (pontachrome blue black R), whilst beryllium forms a fluorescent complex with quinizarin. 

The procedure utilises eriochrome blue black RC (also called pontachrome blue black R Colour Index No. 15705) at a pH of 4,8 in a buffer solution. Beryllium gives no fluorescence and does not interfere iron, chromium, copper, nickel, and cobalt mask the fluorescence fluoride must be removed if present. The method may be adapted for the determination of aluminium in steel. 

Aluminon, haematoxylin, eriochiome cyanine B, alizarin S, quinalizarin, oxine,b morin,c pontachrome blue black Rc... 

Pontachrome Blue-Black R (zinc salt of 4-sulfo-2,2 -dihydroxyazo-naphthalene, C. I. Mordant Black 12) gives an orange-red fluorescence with aluminum salts in acetic acid solution Idn. Limit 2 y A1 in 1 ml). This test appears to be specific for aluminum Be, Zn, and Ga, which behave similarly to aluminum in the fluorescence reaction with morin, do not react with this dyestuff. It is probable that this reaction can be carried out as a spot test. 

---