Determination of Triazole Fungicides in Vegetable Samples by Magnetic Solid-Phase Extraction with Graphene-Coated Magnetic Nanocomposite as Adsorbent Followed by Gas Chromatography–Mass Spectrometry Detection

A graphene-based magnetic nanocomposites (G-Fe3O4 MNPs) was synthesized and used as the adsorbent for the extraction of some triazole fungicides (triadimefon, paclobutrazol, hexaconazole, myclobutanil, diniconazole, propiconazole, and tebuconazole) in cucumber, cabbage, and tomato samples prior to gas chromatography–mass spectrometry detection. Various experimental parameters affecting the extraction efficiencies, such as the amount of G-Fe3O4 MNPs, extraction time, pH and salt concentration of the sample solution, and desorption conditions were investigated. Under the optimized experimental conditions, the enrichment factors of the method for the analytes were in the range from 461 to 697. The signal response was linear in the range of 0.5–35.0 ng g−1 for all the analytes with the correlation coefficients ranging from 0.9810 to 0.9986. The limits of detection (S/N = 3) of the method for the analytes were between 0.01 and 0.10 ng g−1. The recoveries of the method for the seven triazoles were in the range from 84.4 to 108.2 % with RSDs between 3.4 and 10.6 %.