Rapid, selective and direct spectrophotometeric determination of aliphatic amines with m-dinitrobenzene Z.M. Siddiqi *, D. Pathania Department of Applied Chemistry, Dr B.R. Ambedkar National Institute of Technology, Jalandhar, Punjab 144011, India Received 18 November 2002; received in revised form 7 March 2003; accepted 18 March 2003 Abstract Color reaction has been studied for identification and spectrophotometric determination of aliphatic amines at room temperature by m-dinitrobenzene (m-DNB) as reagent. The l 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. # 2003 Elsevier B.V. All rights reserved. Keywords: Spectrophotometery; Aliphatic amines; m-Dinitrobenzene 1. Introduction For the detection of aliphatic amines different reagents are being attempted so as to get rapid, selective, stable and direct method. 1,2-Naphtha- quinone-4-sulphonic acid sodium salt has been used widely and has a number of useful applica- tion as reagent for determination of primary amines in the sample of water. This reagent form violet color at pH 10.2  /10.4 [1]. The interaction of n-alkylamine with chloranil has been investigated [2], which involves the participation of electron donor  /acceptor (EDA) complex between the pri- mary aliphatic amine and chloranil resulting in mono and di-substituted products. Primary, sec- ondary and tertiary amines, both aliphatic and aromatic amine, are shown to react with p- chloranil and form blue to purple color in diox- ane/2-propanol (1:4 v/v) [3]. The colored com- pound formed was stable for 8 h at room temperature, depending on the amine and solvent used. Some new 9-substituted 10-methyl acridi- nium trifluoromethanesulfonates salt have been synthesized and shown to react in methanol with aniline and n-butylamine to form derivatives which absorb strongly at 445 and 439 nm, respectively [4]. The reaction between 1-fluro-2,4- dinitrobenzene and aliphatic amines [5], 1-fluoro * Corresponding author. Fax:  /91-181-29-3653. E-mail address: siddiqizm@lycos.com (Z.M. Siddiqi). Talanta 60 (2003) 1197  /1203 www.elsevier.com/locate/talanta 0039-9140/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0039-9140(03)00228-5