Novel Dispersive Micro-Solid-Phase Extraction Combined with Ultrahigh-Performance Liquid Chromatography–High-Resolution Mass Spectrometry To Determine Morpholine Residues in Citrus and Apples

• Published in: Journal of agricultural and food chemistry 2015-01, Vol.63 (2), p.485-492
• Main Authors: Chen, Dawei, Miao, Hong, Zou, Jianhong, Cao, Pei, Ma, Ning, Zhao, Yunfeng, Wu, Yongning
• Format: Article
• Language: English
• Subjects: acetonitrile; ammonium hydroxide; apples; cation exchange; Chromatography, High Pressure Liquid - methods; Citrus; Citrus - chemistry; cleaning; detection limit; Drug Residues - chemistry; Drug Residues - isolation & purification; Food Contamination - analysis; formates; formic acid; Fruit - chemistry; hydrophilic interaction chromatography; Malus - chemistry; mass spectrometry; Mass Spectrometry - methods; morpholine; Morpholines - chemistry; Morpholines - isolation & purification; nylon; Solid Phase Microextraction - methods
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf5041178

This paper presents a new analytical method for the determination of morpholine residues in citrus and apples using a novel dispersive micro-solid-phase extraction (DMSPE), followed by ultrahigh-performance liquid chromatography–high-resolution mass spectrometry (UHPLC–HRMS). Samples were extracted with 1% formic acid in acetonitrile/water (1:1, v/v) and then cleaned up using the DMSPE procedure. Morpholine from the extract was adsorbed to a polymer cation exchange sorbent and eluted with ammonium hydroxide/acetonitrile (3:97, v/v) through a 1 mL syringe with a 0.22 μm nylon syringe filter. All of the samples were analyzed by UHPLC–HRMS/MS on a Waters Acquity BEH hydrophilic interaction chromatography column using 0.1% formic acid and 4 mM ammonium formate in water/acetonitrile as the mobile phase with gradient elution. The method showed good linearity (R 2 > 0.999) in the range of 1–100 μg/L for the analyte. The limit of detection and limit of quantitation values of morpholine were 2 and 5 μg/kg, respectively. The average recoveries of morpholine from the citrus and apple samples spiked at three different concentrations (5, 20, and 100 μg/kg) were in a range from 78.4 to 102.7%.