Enantiomeric separation of type I and type II pyrethroid insecticides with different chiral stationary phases by reversed‐phase high‐performance liquid chromatography

Abstract

The enantiomeric separation of type I (bifenthrin, BF) and type II (lambda-cyhalothrin, LCT) pyrethroid insecticides on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC chiral columns was investigated by reversed-phase high-performance liquid chromatography. Methanol/water or acetonitrile/water was used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase composition, column temperature, and thermodynamic parameters on enantiomer separation were carefully studied. Bifenthrin got a partial separation on Lux Cellulose-1 column and baseline separation on Lux Cellulose-3 column, while LCT enantiomers could be completely separated on both Lux Cellulose-1 and Lux Cellulose-3 columns. Chiralpak IC provided no separation ability for both BF and LCT. Retention factor (k) and selectivity factor (α) decreased with the column temperature increasing from 10°C to 40°C for both BF and LCT enantiomers. Thermodynamic parameters including ∆H and ∆S were also calculated, and the maximum R were not always obtained at lowest temperature. Furthermore, the quantitative analysis methods for BF and LCT enantiomers in soil and water were also established. Such results provide a new approach for pyrethroid separation under reversed-phase condition and contribute to environmental risk assessment of pyrethroids at enantiomer level.

Chiral Separation and Determination of Etoxazole Enantiomers in Vegetables by Normal-Phase and Reverse-Phase High Performance Liquid Chromatography

“…Good linearity of lnα versus 1/ T implied the main forces involved in etoxazole enantiomers separation. Similarly, poor linearity indicated multiple interaction forces exist in enantiomers separation [ 34 , 35 ]. For instance, the linear regression of lnα versus 1/ T of lambda-cyhalothrin enantiomers on the Lux Cellulose-3 column is 0.623 with an ACN/H 2 O ratio of 60/40, which implies that multiple interaction forces exist between lambda-cyhalothrin enantiomers and CSP [ 35 ].…”

Enantiomeric Separation and Degradation of Benoxacor Enantiomers in Horticultural Soil by Normal-Phase and Reversed-Phase High Performance Liquid Chromatography

“…The excellent linearity of lnα vs 1/T suggests that it is one of the primary forces involved in benoxacor enantiomer separation. Similarly, the weak linearity suggests that several interaction forces are involved in the separation of benoxacor enantiomers [30,31]. For example, the poor linearity of lnα vs. 1/T on a Chiralpak AD column (R 2 of 0.667 and 0.339) indicates that multiple interaction forces operate between chiral stationary phases and benoxacor enantiomers in the Chiralpak AD chiral column [31].…”

Direct Enantiomeric Separation and Determination of Hexythiazox Enantiomers in Environment and Vegetable by Reverse-Phase High-Performance Liquid Chromatography

“…However, temperature sometimes has little effect on chiral resolution. Zhang et al [30] reported the chiral separation of lambda-cyhalothrin enantiomers on a Lux cellulose-3 column with a methanol/water ratio of 95/5 and found the best chiral resolution was obtained at 40 • C with a maximum R s of 4.72.…”

“…The good linearity of lnα versus 1/T implied that only one of these forces was involved in hexythiazox separation. Similarly, poor linearity of lnα versus 1/T would generally indicate multiple interaction forces existed in enantiomers separation [17,29,30].…”