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Enantiomer separation is one of the most important prerequisites for the investigation of environmental enantioselective behavior for chiral pesticides [1-2].In the present study,HPLC is one of the most popular techniques used for the separation and preparative of the enantiomers.With the development of the HPLC method,it is usually desirable to use chiral stationary phases (CSPs) to directly separate the enantiomers because of the simplicity and ease of operation related to this approach [3-4].In this study,the enantiomeric separation of three chiral pesticides,indoxacarb,lambda-cyhalothrin and simeconazole,was investigated on cellulose tris-(3,5-dimethylphenylcarbamate) coated chiral stationary phase (CDMPC-CSP) using HPLC under normal phase.The effects of chromatographic conditions,such as the mobile phase composition including the concentration and type of the alcohol modifiers in hexane,flow rate and column temperature on enantioseparation,were determined.The thermodynamical mechanism of enantioseparation and chiral recognition mechanism had also been discussed.Better separation were achieved using 20% n-propanol for indoxacarb,2% iso-butanol for lambda-cyhalothrin,and 20% iso-propanol for simenconazole as modifiers in hexane at 25 ℃ with the selectivity factor (a) of 1.69,1.82 and 1.70.The resolution factors (Rs) decreased with the flow rates increased over a range from 0.4 to 1.1 mL/min.The retention factors (k1) and selectivity factors (a) for the enantiomers of analytes decreased upon increasing the temperature.The thermodynamic parameters (△Hθ,△Sθ,△R,S△Hθ,△R,S△Sθ) were calculated,the results showed that the lna-1/T plots for racemic chiral pesticides were linear at the range of 15-35℃ in hexane/isopropanol and the chiral separations were controled by enthalpy.Low temperature was better for the resolutions.The different hydrogen bonding,π-π,and dipole-dipole interactions between the enantiomers and the CDMPC-CSP played an important role in chiral discrimination,the fit of the asymmetric portion of the solutes in a chiral cavity or channel of the CSP was also a key point [5-6].