It　is　well　known　that　the　saturated　structure　in　the　non-reducing　end(NRE)　of　heparin/heparan　sulfate(HS)　oligosaccharides　is　lacking　ultraviolet(UV)　232　nm　absorbance(normally　used　for　specific　detection　of　C4-C5　unsaturated　oligosaccharides),　which　poses　a　significant　challenge　for　structure　analysis.　However,　we　found　that　saturated　heparin　oligosaccharides　can　be　detected　at　UV　232　nm　with　sufficient　sensitivity　in　our　previous　research.　In　order　to　further　study　the　UV　232　nm　absorbance　of　the　saturated　structure,　four　saturated　heparin　disaccharides　were　prepared,　and　then　their　UV　232　nm　absorptions　were　analyzed　by　ion-pair　reversed-phase　liquid　chromatography　ion-trap/time-of-flight　mass　spectrometry(RPIP-LC/MS-IT-TOF)　with　photodiode　array　detector.　The　results　show　that　the　saturated　heparin　disaccharides　can　be　detected　with　sufficient　sensitivity　by　absorbance　at　UV　232　nm,　which　still　with　7%-40%　of　UV　232　nm　intensity　of　heparin　unsaturated　disaccharides.　It　seems　that　the　UV　232　nm　intensity　might　be　affected　by　the　sulfate　groups　in　the　disaccharides.　In　addition,　comparing　to　the　common　unsaturated　heparin/HS　disaccharides　as　references,　the　disaccharides　with　GlcNH3+　residues　also　showed　less　sensitivity　at　UV　232　nm.　Finally,　we　simplified　the　sequencing　method　of　the　N-unsubstituted　dp6　oligosaccharides　by　a　simple　UV　detection　method,　combined　with　pH　4.0　HNO2　scission　and　RPIP-LC/MS-IT-TOF　analysis.　This　strategy　offers　possibilities　for　sequencing　at　N-sulfated　residues　using　alternative　pH　1.5　HNO2　scission.　©　2021,　Editorial　Department　of　Chem.　J.　Chinese　Universities.　All　right　reserved.