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%.