Study On Separation Of Several Types Of Chiral Drugs On Chitosan-Based Chiral Stationary Phase

In recent years,chitosan-based chiral stationary phases(CSPs)have attracted widespread attention.These types of stationary phases show excellent chiral recognition capabilities and are well tolerant to organic solvents.This is a type of CSPs with great application potential.In this paper,chitosan bis(3-chloro-4-methylphenylcarbamate)-(cyclopropyl formamide)was used as the chiral stationary phase.High performance liquid chromatography was used to separate the following chiral drugs:Two types of treatment for type 2 diabetes,a novel hypolipidemic agent,five amino alcohols,four azole antifungals,and thirteen others.The effects of different chromatographic conditions on the separation of the above chiral drugs were investigated.In addition,the separation mechanism was briefly described.1.Enantioseparation of vildagliptin and sitagliptin phosphate monohydrate on chiral stationary phase by high performance liquid chromatographyMethods were developed for determining the enantiomers of vildagliptin and sitagliptin phosphate monohydrate by high performance liquid chromatography(HPLC).The influence of alkaline modifiers,organic modifiers and column temperature on the enantioseparation were examined and discussed.The results showed that high enantiomeric separation can be obtained with isopropanol as modifier for the vildagliptin(R_s=4.74),while with ethanol as modifier for sitagliptin phosphate monohydrate(R_s=6.41).The thermodynamic study indicated that the enantioseparation of sitagliptin phosphate monohydrate was enthalpically driven and showed that low column temperature was beneficial to separation,while the separation of vildagliptin was driven by entropy and the higher column temperature was more helpful for the resolution of vildagliptin,at the column temperature of 20~40°C and the mobile phase of ethanol-n-hexane-diethylamine(60/40/0.1,v/v/v).Finally,it was recommended that the compound vildagliptin was separated with the mixture of isopropanol-n-hexane-diethy lamine(80/20/0.1,v/v/v)and the compound sitagliptin phosphate monohydrate was separated with the mixture of ethanol-n-hexane-diethylamine(60/40/0.1,v/v/v),at a flow rate of 0.5 ml/min.2.Enantioseparation of ezetimibe on chiral stationary phase by high performance liquid chromatographyA method was developed for determining the enantiomers of ezetimibe by high performance liquid chromatography.The mobile phase was isopropanol-n-hexane-triflu oroacetic acid(20/80/0.1,v/v/v),the flow rate was 1 ml/min,the detection wavelength was 233.5 nm,and the column temperature was 35°C.The resolution between ezetimibe and R-enantiomer is 3.44;the mass concentration of R-enantiomer has good linearity in the range of 2-10 ug/ml,the linear equation is y=48078x-13712,r~2=0.9993;The limit of quantification and detection limit of R-enantiomer were 2.0 ug/ml and 0.6 ug/ml respectively;the recoveries of R-enantiomers at low,medium,and high concentrations were 101.29%,101.32%,and 102.03%,respectively.RSD(n=3)were 1.27%,1.72%,0.52%,respectively;precision was good;robustness was good.The established method can be used to isolate and determine the R-enantiomer in ezetimibe.3.Separation of five amino alcohol chiral drugs on chitosan chiral stationary phaseThe enantiomeric resolution methods were developed for amino alcohol chiral drugs including propranolol hydrochloride,esmolol hydrochloride,atenolol,clenbuterol hydrochloride,and salbutamol.The effects of different concentrations and different types of organic modifiers on the chiral separation were investigated in the mobile phase.The effects of the acid and alkali modifiers on the chiral separation were investigated.Five amino alcohol chiral drugs,four of which achieved baseline separation.And the baseline separation of the clenbuterol hydrochloride enantiomers within eight minutes was shorter than previously reported.These methods can be used for the separation and analysis of amino alcohols chiral drugs.4.Enantioseparation of azole antifungal chiral drugs on chiral stationary phase by high performance liquid chromatographyMethods were developed for determining the enantiomers of zole antifungal chiral drugs by high performance liquid chromatography.The effects of different mobile phase constituents on the separation of chiral drugs were examined.At 1 ml/min,25°C,when the mobile phase was n-hexane-ethanol(90/10,v/v),the resolution of econazole nitrate,miconazole nitrate,and voriconazole reached 4.04,4.51,and 9.03,respectively.When the mobile phase was n-hexane-isopropanol-ethylenediamine(90/10/0.1,v/v/v),the resolution of the isoconazole nitrate reached 1.82.The peak time of these chiral drugs was within 15 minutes.The composition of the mobile phase is much simpler than the majority of reported methods for the isolation of this class of drugs.These methods are simple and can be used for the separation of azole antifungal chiral drugs.5.Separation of Other Chiral Drugs on Chitosan Chiral ColumnsMethods were established for the enantiomeric resolution of thirteen kinds of chiral drugs that are widely used in clinical practice.The corresponding mobile phase composition was optimized and all thirteen kinds of drug enantiomers achieved baseline separation.Among them,ropivacaine hydrochloride achieved baseline separation within10 minutes,which is shorter than the reported peak time,and the composition of the mobile phase is simple.These methods can be used for the separation of the thirteen kinds of chiral drugs.In this paper,normal phase high performance liquid chromatography was used to establish methods for the resolution of enantiomers of several types of chiral drugs.The influence of different chromatographic conditions on the separation of the chirality was investigated.The mechanism of chiral recognition was initially discussed.The excellent resolution method was verified by methodology.