High-performance liquid chromatographic separations of stereoisomers of chiral basic agrochemicals with polysaccharide-based chiral columns and polar organic mobile phases

Abstract

The separation of the stereoisomers of 23 chiral basic agrochemicals was studied on six different polysaccharide-based chiral columns in high-performance liquid chromatography with various polar organic mobile phases. Along with the successful separation of analyte stereoisomers, emphasis was placed on the effect of the chiral selector and mobile phase composition on the elution order of stereoisomers. The interesting phenomenon of reversal of enantiomer/stereoisomer elution order function of the polysaccharide backbone (cellulose or amylose), type of derivative (carbamate or benzoate), nature, and position of the substituent(s) in the phenylcarbamate moiety (methyl or chloro) and the nature of the mobile phase was observed. For several of the analytes containing two chiral centers all four stereoisomers were resolved with at least one chiral selector/mobile phase combination.

Chiral separation of lenalidomide by liquid chromatography on polysaccharide‐type stationary phases and by capillary electrophoresis using cyclodextrin selectors

“…On Chiralpak AS, Chiralcel OJ, and Chiralcel OD columns with alcohol-type eluents, the elution order was R-LEN followed by S-LEN, while on Chiralpak AD column (independent of the applied mobile phases) and Chiralcel OD column with ACN, the elution order was reversed, S-LEN followed by R-LEN. Mobile phase dependent reversal of enantiomer elution order on polysaccharide-type CSPs has been described earlier [18,19,23]; this phenomenon can explain the different nature of alcohol-type modifier and ACN. The protic alcohols employed are stronger H-bond competitors than ACN; however, ACN is disadvantageous for π-π interactions, so different interactions can be formed between the analyte T A B L E 1 Chromatographic data, retention factor of the first eluting enantiomer (k 1 ), selectivity factor (α), resolution (R s ), and elution sequence on the polysaccharide-type columns in polar organic mode (flow rate: 0.5 mL/min) and chiral selectors in ACN and MeOH [24,25], which can cause reversal of elution order.…”

Enantiomeric quality control of R‐Tofisopam by HPLC using polysaccharide‐type chiral stationary phases in polar organic mode

“…These CSPs are widely applicable in normal phase, reversed‐phase and polar organic mobile phase modes. The application of polar organic mode using neat alcohols or acetonitrile (ACN) as mobile phase is especially interesting, since it presents numerous advantages, including short analysis time, high efficiency, better signal/noise ratio and commonly higher solubility of the analytes in the mobile phase .…”

Enantioseparation of racecadotril using polysaccharide‐type chiral stationary phases in polar organic mode

“…Most of currently available chiral polysaccharide‐based columns can be used in normal‐phase, reversed‐phase, and polar organic mobile phase modes, making these CSPs universally applicable . Nowadays, polar organic mode has been well established for analytical and preparative‐scale enantioseparation due to their advantages, such as short analysis time, high efficiency, better signal/noise ratio, and commonly higher solubility of the analytes in the mobile phase …”

“…9 Nowadays, polar organic mode has been well established for analytical and preparative-scale enantioseparation due to their advantages, such as short analysis time, high efficiency, better signal/noise ratio, and commonly higher solubility of the analytes in the mobile phase. [11][12][13] To the best our knowledge, validated chiral methods are not available for RAC, despite the growing interest in analytical characterization of the drug. [14][15][16][17] Because of the different pharmacological effects of RAC enantiomers and possibilities of future chiral switches, development of a sensitive, precise, and reliable enantioselective method is required.…”