Reversed phase-liquid chromatography of primary and secondary aliphatic amines after derivatization combined with electrochemical detection

An analytical procedure has been developed for the determination of primary and secondary aliphatic amines by liquid chromatography with electrochemical detection (LC-ECD). Aliphatic amines, such as propylamine (PA), butylamine (BA), 2-pentylamine (2-PA), dimethylamine (DMA), diethylamine (DEA) and dipropylamine (DPA) react readily with salicylic acid chloride (SAC) to produce electroactive amide derivatives with good chemical stability. The isocratic elution pattern of synthetic mixtures of the investigated amines on a reversed-phase column is shown. Hydrodynamic voltammograms of standard compounds are presented. The detection limits monitored with an EC detector are compared with those of an UV detector. The method was sensitive enough to detect the derivatives in the picomol range. The method was also applied for the determination of amines in plasma and urine using 2-PA and DPA as model substances. Following a solid phase extraction and derivatization, the compounds could be detected in the lower ng range/ml biological material.