Spectrophotometric determination of 1-naphthylamine in aqueous solution by coupling with diazotised 4-aminoacetophenone

Abstract

A simple, rapid and sensitive spectrophotometric method for the trace determination of 1-naphthylamine in aqueous solution is described. It depends on the coupling reaction of the intended compound with diazotised 4-aminoacetophenone reagent to form an intense pink, water-soluble azo dye that is stable and shows maximum absorption at 520 nm. Adherence to Beer's law is observed over the concentration range 5–100 µg of 1-naphthylamine in a final volume of 25 ml, i.e., 0.2–4 p.p.m., with a molar absorptivity of 4.22 × 10⁴ l mol^–1 cm^–1, a relative error of –0.1 to + 1.5% and a relative standard deviation of 0.1–2.4%, depending on the concentration level. Further, the method does not require either temperature control or solvent extraction. Interferences due to foreign species have been examined.