Rapid, selective and direct spectrophotometeric determination of aliphatic amines with m-dinitrobenzene

Color reaction has been studied for identification and spectrophotometric determination of aliphatic amines at room temperature by m-dinitrobenzene (m-DNB) as reagent. The λmax value ranges from 458 to 570 nm. This is a simple and rapid method for determination of aliphatic amines in the acidic, water and acetone medium. Beerʹs law is verified for methylamine, dimethylamine, trimethylamine and n-butylamine in the range of 0.5–8 mg l−1. The effect of pH on the molar absorptivity is investigated for a representative primary amine i.e. methylamine and it was observed that molar absorptivity increases from acidic to basic pH, with a sharp increase at pH 12. The kinetic of reaction was also studied and found that reaction time has marked effect on the molar absorptivity of electron donor–acceptor (EDA) complex. The detection of methyl amine has been reported in three real samples of water.