Simultaneous Determination of Quinoxalines in Animal Feeds by a Modified QuEChERS Method with MWCNTs as the Sorbent Followed by High-Performance Liquid Chromatography

Abstract

A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method using multi-walled carbon nanotubes (MWCNTs) as sorbent solvent combined with HPLC was developed for the simultaneous determination of olaquindox, carbadox, mequindox, quinocetone, and cyadox in animal feeds. Sample preparation was performed by ultrasound-assisted extraction (UAE) with methanol-acetonitrile-H2O (50:25:25, v/v/v) as extraction solvent and a final clean-up using QuEChERS with MWCNTs (30–50 nm) as the sorbent solvent. To achieve the optimum conditions for extraction the target analytes and modified QuEChERS toward target analytes, several parameters, including extraction solvent and time as well as the type and amount of the adsorbents were investigated. The detection and quantification of five quinoxalines were performed by HPLC-UV. The chromatographic separation was performed on a C18 column using methanol-water as the mobile phase. The limits of detection and quantification of the analytes ranged from 0.2 to 0.4 and 1.0 to 1.5 mg/kg, respectively. The recoveries from spiked sample ranged from 66.0 to 95.6% with the relative standard deviations of less than 14.1%. The developed method was successfully utilized to monitor real samples, demonstrating that it is simple, fast, and robust, and may be used to monitor quinoxalines residues in animal feeds.