| Although the enantiomers of chiral compounds have high similarity in physical and chemical property,their biological activity,toxicity and pharmacokinetics are significantly different from each other,which posed great threats to food and drug safety.Since the tragedy of "thalidomide incidence",the chiral separation has aroused increasing attention from the international community.Therefore,the exploration of versatile chiral separation materials has becoming a hot research.High performance liquid chromatography(HPLC)in combination with various chiral stationary phases(CSPs)has developed as one of most popular methods in chiral separations.Among various CSPs,cyclodextrins(CDs)-based species have been vigoriously developed,The bridged bisCDs have characteristics of unique synergistic inclusion and multiple recognition abilities,which have beeing extensively studied in the fields of molecular recognition,molecular switches,carriers,asymmetric catalysis,biomimetic enzymes,etc.However,there are fewer reports on the bridged bisCDs in chromatographic separation,thereby the bridged CD-based CSPs remains to be developed extensively.In this study,in order to make up for the shortcomings of current CD-CSPs somehow,two novel bridged bisCDs and their related CSPs with high selectivity were prepared.firstly,two characteristic bridging linkers were designed to synthesize two bridged bis(?-CD),which were then bonded onto the silica gel to prepare two kinds of bis((?-CD)-bonded CSPs,including a stilbene diamido-bridged bis((?-CD)-bonded phase(SBCDP)and a diureido-bridged bis(?-CD)-bonded phase(UBCDP).And the structures of them were characterized by the mass spectrometry,nuclear magnetic resonance,infrared spectroscopy,elemental analysis and thermogravimetric analysis.Furthermore,the chromatographic performances of the two CSPs were systematically evaluated by separating several sets of chiral drugs and pesticides such as flavanones,blockers,triazole pesticides,amino acids,etc.Moreover,the chromatographic conditions including the composition of mobile phases,pH values and column temperature were investigated and optimized in detail.Meanwhile,a comparative study with a native 3-CD-bonded phase(CDCSP)was conducted,during which some separation mechanisms were preliminarily discussed.The two newly-prepared CSPs exhibited better chiral separation ability than the CDCSP,which was mainly related to the synergistic inclusion of bridged bisCDs that overcame the limitation of the small cavity of native cyclodextrin.By using the two prepared CSPs respectively,a new method for the rapid determination of enantiomers in arolol hydrochloride tablets by HPLC-Fluorescence was estabilised,and a LC-MS/MS method with high selectivity and sensitivity for the simultaneous separation of multiple triazole pesticide enantiomers in common fruits and vegetables was proposed as well.The first chapter mainly focused on the threats to food and drug safety caused by the enantiomers of chiral compounds and emphasized the importance of chiral separation and analysis.In addition,the current chiral stationary phases(CSPs)were summarized,especially the p-CD-based ones were emphasized on their growth,deficiencies and potentially available solutions were concluded and expected.The extensive applications of bridged bisCDs in the fields of artificial mimetic enzymes,molecular recognitions,drug deliveries were concisely summarized,and the promising applications in separation science was analyzed according to the structures of bridged bisCDs either.In the second chapter,by coupling two 6-deoxy-6-amino-?-cyclodextrin with a stilbene dicarboxylic acid,introducing a rigid and conjugated stilbene diamido-bridging linker to synthesize a stilbene diamido-bridged bis(?-CD),which was then bonded onto the surface of silica gel to obtain a stilbene diamido-bridged bis(?-CD)-bonded CSP(SBCDP).The structure of it was characterized by the mass spectrometry,nuclear magnetic resonance,infrared spectroscopy,elemental analysis and thermogravimetric analysis.Then the chromatographic performance of SBCDP was systematically evaluated by separating 23 chiral drugs and pesticides,including trimeprazine,praziquantel,flavanones,blockers and triazole pesticides in the reversed-phase chromatography or the polar organic mode.Meanwhile,some chromatographic conditions that affect the chiral separation including the mobile phase composition,pH and column temperature were investigated in detail.The results showed that all tested analytes were completely separated on SBCDP with high resolutions(1.51?5.15)within about 25 min,and the enantioseparation resolutions of flavanone and imazalil were up to 5.15 and 4.38,respectively.Compared with the native ?-CD-bonded phase(CDCSP),SBCDP had a better chromatographic performance.For example,those enantiomers of the trimeprazine,praziquantel,flavanone and imazalil that could not be separated by CDCSP were separated by SBCDP with high resolutions instead.Unlike the small cavity(-0.65 nm)of native CD,the bridged bisCD,with a V-shape structure formed by two adjacent cavities and a functional bridging linker,was able to recognize and separate more solutes,which was mainly related to the synergistic inclusion and sophisticated recognition effect of it.In the third chapter,the hexamethylene diisocyanate was used as coupling agent,as a long flexible alkyl chain to connect two 6-deoxy-6-hydroxyethylamino-?-CD units to synthesize a diureido-bridged bis(?-CD),which was boned onto silica gel to obtain a diureido-bridged bis(?-CD)-bonded phase(UBCDP),and the structure of it was characterized either.Then the chromatographic performance of UBCDP was comprehensively evaluated by separating 25 chiral drugs or pesticides such as flavanones,triazole pesticides,dansyl-amino acids.In detail,compared with a native?-CD-bonded phase(CDCSP),some separation mechanisms of UBCDP were preliminarily discussed.As a consequence,UBCDP performed better chiral separation ability during enantioseparations with the resolutions in a range of 1.52?4.35 for 2'-hydroxyflavanone,dansyl-leucine and hexaconazole,while the CDCSP only resolved partial solutes with lower resolutions.In the fourth chapter,by using the UBCDP prepared in the third chapter and optimizing the composition,flow rate of mobile phase,column temperature under the polar organic mode,the enantiomers of arotinolol hydrochloride were separated within 25 mins.Furthermore,a new method for enantiomeric determination of arotinolol hydrochloride tablets by high performance liquid chromatography with fluorescence detector was established,wherein two enantiomers presented good linear relationship(R2?0.9992),satisfied recoveries(92.8%-105.1%)and high sensitivities(LOD?0.025 mg/L).This method was simple to operate,and will be worth using as a preliminary method for quality control and pharmacokinetic study of arotinolol hydrochloride.In the fifth chapter,by using SBCDP prepared in the second chapter,a LC-MS/MS method was established for a simultaneous determination of six triazole pesticides(hexaconazole,tebuconazole,triticonazole,flutriafol,etc.)in common fruits and vegetables(apple,strawberry,banana,etc.).This method had characteristics of high sensitivity and selectivity(LOD,0.05?0.10 ?g/kg;LOQ,0.20?0.30 ?g/kg),short analysis time(within 50 mins),wide linear range(0.05?20 ?g/mL),high recoveries(76.1?103.4%)and good reproducibility(RSDs,2.6?11.9%),which equipped a promising application prospect in enantiomeric residual determination of triazole pesticide in foodstuffs. |
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