Enantioselective determination of acaricide etoxazole in orange pulp, peel, and whole orange by chiral liquid chromatography with tandem mass spectrometry

Abstract

An efficient enantioselective method for the determination of etoxazole in orange pulp, peel, and whole orange was developed using liquid chromatography with tandem mass spectrometry. The enantioseparation was performed on a Chiralpak AD-3R column at 30ºC using acetonitrile with 0.1% formic acid solution (80:20, v/v) as the mobile phase in less than 5 min. Quantification was achieved using matrix-matched standard calibration curves. The overall mean recoveries for two enantiomers from orange pulp and whole orange were 91.0-99.6% and the orange peel was 92.6-103.1%, with relative standard deviations of 0.8-5.4% intraday and 2.0-4.8% interday at 1, 10, and 100 μg/kg levels, and 1.3-5.2% intraday and 3.5-4.3% interday at 5, 50, and 500 μg/kg levels, respectively. The limits of quantification for all enantiomers in three matrices did not exceed 5 μg/kg. Moreover, the absolute configuration of etoxazole enantiomers had been determined by the combination of experimental and predicted electronic circular dichroism spectra, and the first eluted enantiomer was confirmed as (S)-etoxazole on a Chiralpak AD-3R column while (R)-etoxazole was first on three cellulose chiral columns. The application of the proposed method to real sample analysis suggests its potential use in enantioselective determination of etoxazole enantiomers in citrus.

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

“…After that, the enantiopure enantiomers were injected into normal-phase and reverse-phase HPLC with different chiral columns to confirm the elution order ( Figure 4 ). According to the absolute configuration and elution order of etoxazole enantiomers confirmed by a previous study [ 10 , 13 , 31 ], the first eluted enantiomer on the Chiralpak AD column was S -etoxazole, while the first eluted enantiomer on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC columns was R -etoxazole. Furthermore, the elution order of etoxazole enantiomers on the same chiral column is identical no matter which of HEX/IPA, HEX/BuOH, MEOH/H 2 O, or ACN/H 2 O was used as the mobile phase.…”

“…in agriculture. The mode of action (MoA) of etoxazole is to affect adult egg development by inhibiting chitin biosynthesis, thus it is used against nymphs, mite larvae, eggs, and is safe for adult mites [ 3 , 10 , 11 , 12 , 13 ]. Etoxazole has an asymmetric chiral carbon atom in its chemical structure and consists of two enantiomers ( R -etoxazole and S -etoxazole, at a ratio of 1:1) [ 3 ].…”

“…Etoxazole has an asymmetric chiral carbon atom in its chemical structure and consists of two enantiomers (R-etoxazole and S-etoxazole, at a ratio of 1:1) [3]. In recent years, etoxazole residue has been reported in soil, berry, apple, orange, and vegetables [13][14][15][16], which poses a high risk for human and environmental health. Enantiomer separation of chiral pesticides is the first step in enantiomer risk assessment.…”

Enantioselective Determination of Polycyclic Musks in River and Wastewater by GC/MS/MS

“…They have been detected in municipal sewage effluent and various environmental samples such as surface water, marine, soil, sediment and aquatic biota in many countries. The occurrence of synthetic musks in environmental samples could negatively affect the health of the ecosystem and humans, owing to persistent, chronic exposure of aquatic organisms [ 7 , 8 , 9 , 10 , 11 ].…”

Determination of multi-pesticide residue in tobacco using multi-walled carbon nanotubes as a reversed-dispersive solid-phase extraction sorbent

“…Pesticides are widely used in most sectors of agricultural production, including tobacco and tobacco products, to provide reliable supplies to consumers and ensure high profits to farmers . However, pesticide residues in agricultural products are frequently detected .…”