Salt-Assisted Graphene Oxide Dispersive Solid Phase Microextraction for Sensitive Detection of Malachite Green and Crystal Violet by HPLC

In this study, an efficient sample pretreatment method, salt-assisted graphene oxide dispersive solid phase microextraction (SA-GO-DSPME), was established for extraction of malachite green (MG) and crystal violet (CV). The dispersive graphene oxide was found to be easily aggregated and completely centrifuged in the presence of NaCl. The adsorption kinetic of SA-GO-DSPME was shown to be quite fast (equilibrium time = 5 min). Key parameters that influenced extraction efficiency including sample pH, the eluent type, GO amount, extraction time, NaCl concentration and centrifuging time were investigated. Coupled with SA-GO-DSPME, high-performance liquid chromatography (HPLC) could be used for sensitive detection of MG and CV with detection limits down to 1.7 and 0.3 ng mL−1 for MG and CV, respectively. The relative standard deviations for extraction reproducibility (n = 5) were 1.8 % for MG and 3.8 % for CV. The proposed method has been successfully applied for detection of MG and CV in real water samples, and the recoveries ranged from 89.7 to 116.4 %. This simple and fast extraction method may provide a promising alternative for extraction of trace amount of MG and CV in complicated samples.