Arsenazo III and its analogues-VI( *) Some new photometric reagents for palladium.

Colour reactions of palladium with 2,7-bisazo derivatives of chromotropic acid, containing the o,o'-dihydroxyazo group, are characterized by high sensitivity ( = 60-82 x 10(2)) and good contrast (Deltalambda = 70-80 nm) and permit determination of palladium over a wide range of acidity (from pH 5 to 4N sulphuric acid). Many other metals, including the other platinum metals, do not interfere when present in up to 100-fold amounts.