This paper describes the use of head-column field-enhanced sample stacking for on-line sample concentration in MEKC; the method has been applied to the determination of C1-C9 aliphatic amines after their pre-capillary derivatization with 3-(4-carboxybenzoyl) quinoline-2-carboxaldehyde (CBQCA). The optimum derivatization, on-line concentration and separation conditions for these aliphatic amines were investigated in detail. The optimized molar ratio of CBQCA to amines was found to be 120:1, and 50 mmol/L borate buffer (pH 9.5) was used for derivatization in order to achieve high efficiency. Nine imidazole aliphatic amines were baseline separated within 12 min by using 50 mmol/L of sodium borate (pH 9.5) and 15 mmol/L of SDS as running buffer. Under the optimum conditions, the detection limits of these nine aliphatic amines ranged from 1.2 to 3.8 pmol/L. S/N = 3, which was about 49 similar to 173-fold lower than those of conventional sample injections. After validation, the developed method was applied to the determination of C1 similar to C9 aliphatic amines in river water with the average recoveries of 86.7-105%.