Graphene-based magnetic nanoparticles, comprising zero-valent iron, iron oxide–oxyhydroxide and
graphene, were prepared through a simple one-step synthesis method, and subsequently applied to
magnetic solid-phase extraction for the determination of trace carbamate pesticides in tomatoes
coupled with high performance liquid chromatography. The properties of the nanocomposites were
confirmed by using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and
vibrating sample magnetometer. The components within the nanocomposites endowed the material with
high extraction performance and manipulative convenience. Compared with reduced graphene oxide, the
as-prepared G-MNPs showed the better extraction efficiencies for the carbamate pesticides thanks to
the contribution of the iron-containing magnetic nanoparticles to the adsorption capacity of the
nanocomposites. Various experimental parameters affecting the extraction efficiency had been
investigated in detail. Under the optimal conditions, the method provided high enrichment factors
ranging from 364 to 434, good line- arities ranging from 5 to 200 ng g - 1 for metolcarb, baygon
and methiocarb and 10 to 200 ng g - 1 for carbofuran and isoprocarb, low limits of detection
ranging from 0.58 to 2.06 ng g - 1, and satisfactory spiked recoveries (between 90.34% and
101.98% with the relative standard deviation values from 1.21% to
5.93%). It was confirmed that this novel method was an efficient pretreatment and enrichment
procedure and could be successfully applied for extraction and determination of trace carbamate
pesticides in complex matrices.