Determination of microcystins in environmental water samples with ionic liquid magnetic graphene

Microcystins is a class of monocyclic of heptapeptides with many different isomerides. It has become potential hazardous material in water environment for its toxic, distribution and stability. This project worked on a method for determination of trace microcystin (MC-LR and MC-RR) in environmental waters. The ionic liquid magnetic graphene (IL@MG) was prepared and applied to the concentration and determination of microcystins, based on magnetic solid phase extraction (MSPE), and coupled with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The ionic liquid magnetic graphene was prepared by coprecipitatial synthesis and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), specific surface area (BET), pore size distribution (BJH) and magnetic hysteresis loop. The experimental parameters of magnetic solid phase extraction, including amount of IL@MG, pH, extraction time and elution solvent were investigated by a univariate method and orthogonal screening. The method showed good linearity in the range of 0.01-10.0 g/L and 0.005-10.0 μg/L for MC-LR and MC-RR, when the pH of water samples was 4.00 and 10.0 mg adsorbents were used to extract targets for 18 min. The lowest detection limit was 0.414 ng/L and 0.216 ng/L for MC-LR and MC-RR respectively. The recoveries of the microcystins were in the range of 83.6-100.9%, and the relative standard deviation was less than 7.59%. The trace amount of MC-LR (0.020 μg/L) and MC-RR (0.003 μg/L and 0.021 μg/L) was detected in actural water samples. Attributed to its simple operator, low detection limit and high sensitivity, this method could be used for the detection of trace microcystins in water samples.