## 1 Introduction  
Insecticides (e.g., organophosphorus pesticides (OPPs), organochlorine pesticides (OCPs), pyrethroids, and carbamates) are widely used for pest control in agriculture and residential places. Nevertheless, many insecticides are carcinogenic, teratogenic, and mutagenic to human cells. Long-term accumulation in vivo of insecticides can seriously harm the nervous, genital, and immune systems of the human body [1]. Maximum residue limits (MRLs) were set strictly by many organizations toward insecticides. For instance, the European Union (EU) has set the MRLs at 0.01-0.3 ug g\({}^{-1}\) for insecticides, such as OPPs and pyrethroids, in vegetables [2]. Therefore, developing an effective analytical method for trace-level determination of insecticide residues is indispensable and highly necessary. Extensive research has been performed to develop the analytical methods and techniques for insecticide residues [3, 4], especially for the simultaneous determination of multiresidues. Owing to its high separation ability and satisfactory qualitative and quantitative performance, chromatographic technology is often employed to measure insecticides in different samples. Gas chromatography (GC) and liquid chromatography (LC) equipped with mass spectrometers, such as single quadrupole or triple quadrupole, are frequently utilized for the accurate and rapid qualification and quantification of insecticide residues in food samples. Despite the advantages, multiresidue analysis suffers from the interference from matrix compounds, which compromises accuracy, replicability, and sensitivity of the analysis. Therefore, the separation of pesticides from complex food samples before chromatographic analysis is usually a critical procedure. Many sample preparation techniques have been applied to extract and preconcentrate the pesticides, such as liquid-liquid extraction [5], solid-phase extraction (SPE) [6], solid-phase microextraction (SPME) [7], dispersive liquid-liquid microextraction (DLLME) [8], and dispersion-solidification liquid-liquid microextraction [9]. Magnetic solid-phase extraction (MSPE), integrating extraction and separation, as well as clean-up and concentration of analytes into a single step, has attracted much attention in sample pretreatment. For MSPE, magnetic sorbents are directly dispersed into sample solutions, and the dispersive mode facilitates the increase of interfacial area between analytes and sorbents. Therefore, the extraction efficiency of MSPE can be improved compared with the conventional SPE. Moreover, the use of magnetic sorbent makes the phase separation step much convenient and avoids the traditional centrifugation or filtration process. Among different materials, graphene-based magnetic nanomaterials have received great attention owing to their unique physicochemical properties [10, 11], high surface-to-volume ratio, and large sorption capacity. A few research groups have managed to fabricate magnetic graphene nanomaterials for the preconcentration or removal of some pollutant residues [12, 13]. However, recent studies have shown that restacking and agglomeration of graphene sheets are difficult to avoid while synthesizing magnetic composites [14]; restacking and agglomeration may decrease the specific surface area of graphene, affecting its extraction efficiency. The restricted selectivity of graphene is another limitation. Generally, graphene material is a non-polar, hydrophobic sorbent with sp\({}^{2}\)-hybridized carbon atoms, and they show a partial affinity for hydrophobic compounds/aromatic structure and interact weakly with polar, ionic or other types of compounds [15]. The extraction efficiency of graphene material is easily limited for some types of target analytes, which was undesired for analysis of multi-class residues [16]. Additionally, many undesired impurities would be extracted from the sample matrix along with the analyte, affecting the analytical performance of the methods [17].