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 lambda(max) 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. Beer's 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.