Chemical bonding of oxygenated carbon nitride nanosheets onto stainless steel fiber for solid-phase microextraction of phthalic acid esters

In this work, oxygenated carbon nitride nanosheets (OCNNSs) were first introduced to the field of analytic chemistry for solid-phase microextraction (SPME). The rich hydroxyl and carboxyl contents of OCNNSs provided abundant adsorption sites. The coated stainless steel fibers, synthesized by the layer-by-layer chemical bonding method, had good chemical stability (in organic solvents), long life (durability ≥ 150 cycles), and good reproducibility (RSDs ≤ 9.2%). This novel OCNNSs-coated fiber was used for SPME with gas chromatography-mass spectrometry (GC-MS) for the analysis of phthalic acid esters (PAEs) in three types of food products (seafood, samshu, and instant noodles). Under optimal conditions, the limits of detection (LODs) for the PAEs ranged from 0.1 to 10.0 pg mL^-1, and recovery was in the range of 80.0-118.1%. These novel coated SPME fibers displayed excellent separation and enrichment properties, which suggest a pretreatment application for analysis of PAEs.