In　order　to　improve　the　sensitivity　of　CE-ESI-MS　for　the　analysis　of　brain-gut　peptides,　a　solid-phase　extraction　combined　with　field-amplified　sample　injection　was　used　for　the　pre-concentration　of　the　brain-gut　peptides.　Compared　with　the　conventional　pressure　injection　method,　the　sensitivity　in　the　detection　of　brain-gut　peptides　was　improved　more　than　100-fold.　The　possible　factors　affecting　sample　stacking,　such　as　the　sample　matrix,　the　composition　and　the　length　of　the　water　column,　the　types　and　the　volumes　of　eluent,　have　been　investigated　in　detail.　Under　the　optimum　conditions,　the　detectable　concentration　of　brain-gut　peptides　was　found　to　be　as　low　as　0.02　mu　M.　A　linear　response　concentration　for　the　detection　was　developed　in　the　range　of　0.08-25　mu　mol/L.　A　real　sample　of　human　cerebrospinal　fluids,　which　was　spiked　with　brain-gut　peptides,　was　also　examined　in　order　to　evaluate　the　reliability　of　the　proposed　approach.　The　recovery　of　the　method　was　in　a　range　from　69.2　to　85.4%.　The　method　was　found　to　be　reliable,　accurate　and　potentially　applicable　for　clinical　drug　analysis.