SYNTHESIS OF 5-METHYLBENZOTHIAZOLYL)AZO]-5-DIMETHYLAMINOBENZOIC ACID AND ITS APPLICATION TO THE SPECTROPHOTOMETRIC DETERMINATION OF NICKEL

A new thiazolylazo reagent, 5-methylbenzothiazolyl)azo]-5-dimethylamin obenzoic acid (5-Me-BTAMB) was synthesized. Its chromogenic reaction w ith microamounts of nickel was studied in detail, and the stability co nstants of the complexes of Ni2+, Co2+, Fe2+, Cu2+ and Pd2+ were deter mined, 5-Me-BTAMB reacts with nickel(II) in the presence of sodium dod ecyl sulfate to form a stable blue-violet 2:1 complex with an absorpti on maximum at 640 nm. The molar absorptivity of the complex is 1.32 x 10(5) l mol(-1) cm(-1). Beer's law is obeyed in the range 0-10 mu g of nickel(II) per 25 ml. The proposed method was applied to the direct d etermination of microamounts of nickel in aluminium alloys with satisf actory results.