Dual-use ionization source for direct and sensitive detection of trace carbamates residue.

Directly determining trace compounds in actual sample by ambient ionization mass spectrometry (AIMS) has always been a challenge. Due to the excellent adsorption and desorption properties of nanomaterials, AIMS combined with nanomaterials can improve the adsorption and desorption properties of MS. In this work, we developed a molecularly imprinted graphene oxide coated steel sheet (MIGOCS) to be used as a solid phase extraction adsorbent. Graphene oxide was characterized by its strong adsorption abilities, and the surface molecularly imprinted polymer has high selectivity. Here, the MIGOCS coupled with the ambient electrospray ion source was used to detect trace carbamate pesticides in water samples. Meanwhile, the extraction and spray parameters were systematically optimized. The newly developed molecularly imprinted graphene oxide-steel sheet spray-mass spectrometry (MIGO-SS-MS) method has low detection limits (0.05 ∼ 0.4 ng mL) and satisfactory recoveries (83.23 ∼ 97.98 %) for carbamates (CMs). The method can be potentially applied to the determination of CMs in water and food samples.