Chiral separation of aryloxyphenoxy-propionate herbicides in a permethyl-B-cyclodextrin based column. Influence of temperature and mobile phase composition on enantioselectivity

LUBOMIRSKY, ESTER; PADRO JUAN MANUEL; DI LORETO, HÉCTOR; CASTELLS, CECILIA B.*

ELECTROPHORESIS

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2017

0173-0835

We used a permethyl-β-cyclodextrin chiral stationary phase under reversed-phase conditions for the chiral separation of four aryloxyphenoxy-propionate herbicides (fenoxaprop-p-ethyl, quizalofop-p-ethyl and tefuryl and haloxyfop-p-methyl) with mixtures of methanol, ethanol, 2-propanol, n-propanol, tert-butanol, or acetonitrile and water as mobile phases and investigated the influence of mobile phase composition and column temperature (from 0 to 50 ºC) on the separation. The retention factors (k) and selectivity factors (α) of all the herbicides investigated decreased with increasing temperature. The lnα vs. 1/T and lnk vs. 1/T plots for the enantiomers of the chiral pesticides were linear within the range of 0?50 ºC with the alcohols/water mixtures constituting the mobile phase, but the lnk vs. 1/T plots were nonlinear for all the enantiomers chromatographed in acetonitrile/water mixtures. The thermodynamic parameters based on linear van?t Hoff plots were calculated. The influence of temperature and mobile phase composition on the enantioseparation of the solutes has rarely been considered simultaneously. The temperature and the solvents used in the mobile phase, however, were found to have a profound effect on the enantioseparation of these herbicides.