The paper reports the simultaneous fluorescence determination of D,L-tryptophanenantiomer by chiral recognition of β-cyclodextrin for the first time. Chiral discrimination isobserved for fluorescence emission of D- a...The paper reports the simultaneous fluorescence determination of D,L-tryptophanenantiomer by chiral recognition of β-cyclodextrin for the first time. Chiral discrimination isobserved for fluorescence emission of D- and L-tryptophan when complexed toβ-cyclodextrin, and is significantly related to reaction temperature, time and PH. The proposedenantiomeric resolution of D- and L-tryptophan is based on the non-fluorescellce emission ofLtryptophan in β-cyclodextrln solution at 35℃ and after 24 h standing by. The fluorescenceemission and absorbance of L-tryptophan disappear with the Increase of β-cyclodextrin at 35℃ and 24 h standing by, where as it is not observed for D-tryptophan. The detection limitsare 3.1×10-8 mol/L for D-tryptophan and 2.7 ×10-7 mol/L for L-tryptophan, respectively,with a RSD of 1. 0%-2. 6% (n=7). The method has been shown to be accurate with a ratioof 2%(molar ratio) of one enantiomer in the presence of the other. The observed pseudofirst-order rate constant is calculated. The reaction mechanism has been discussed usingpyrene as a fluorescence probe.展开更多
Morroniside consists of two anomeric isomers, α-morroniside and β-morroniside. These two anomeric compounds have been separated by reversed-phase high-performance liquid chromatography(HPLC) using a gradient mobile ...Morroniside consists of two anomeric isomers, α-morroniside and β-morroniside. These two anomeric compounds have been separated by reversed-phase high-performance liquid chromatography(HPLC) using a gradient mobile phase of acetonitrile-water at 7 ℃, and verified to be anomers of morroniside by ESI-TOF-MS. The higher peak in the chromatogram was appointed to α-morroniside according to NMR data reported in previous literature. The molar ratio of α-morroniside to β-morroniside was found to be 2.855∶1 at 25 ℃. Temperature appeared to be an important factor, which affects the separation result, and a better separation was achieved at a lower temperature. The relative peak height of β-morroniside in the total ion current chromatogram measured with positive ion ESI-TOF mass spectrometer was only a half of that in UV chromatogram. This indicates that β-morroniside is less sensitive to positive ion electrospray ionization than the α-isomer.展开更多
文摘The paper reports the simultaneous fluorescence determination of D,L-tryptophanenantiomer by chiral recognition of β-cyclodextrin for the first time. Chiral discrimination isobserved for fluorescence emission of D- and L-tryptophan when complexed toβ-cyclodextrin, and is significantly related to reaction temperature, time and PH. The proposedenantiomeric resolution of D- and L-tryptophan is based on the non-fluorescellce emission ofLtryptophan in β-cyclodextrln solution at 35℃ and after 24 h standing by. The fluorescenceemission and absorbance of L-tryptophan disappear with the Increase of β-cyclodextrin at 35℃ and 24 h standing by, where as it is not observed for D-tryptophan. The detection limitsare 3.1×10-8 mol/L for D-tryptophan and 2.7 ×10-7 mol/L for L-tryptophan, respectively,with a RSD of 1. 0%-2. 6% (n=7). The method has been shown to be accurate with a ratioof 2%(molar ratio) of one enantiomer in the presence of the other. The observed pseudofirst-order rate constant is calculated. The reaction mechanism has been discussed usingpyrene as a fluorescence probe.
文摘Morroniside consists of two anomeric isomers, α-morroniside and β-morroniside. These two anomeric compounds have been separated by reversed-phase high-performance liquid chromatography(HPLC) using a gradient mobile phase of acetonitrile-water at 7 ℃, and verified to be anomers of morroniside by ESI-TOF-MS. The higher peak in the chromatogram was appointed to α-morroniside according to NMR data reported in previous literature. The molar ratio of α-morroniside to β-morroniside was found to be 2.855∶1 at 25 ℃. Temperature appeared to be an important factor, which affects the separation result, and a better separation was achieved at a lower temperature. The relative peak height of β-morroniside in the total ion current chromatogram measured with positive ion ESI-TOF mass spectrometer was only a half of that in UV chromatogram. This indicates that β-morroniside is less sensitive to positive ion electrospray ionization than the α-isomer.
