LAUSR

A graphene oxide-incorporated monolithic column was fabricated and developed as an on-line solid-phase extraction sorbent coupled with LC-MS/MS for the automatic and fast determination of 16 sulfonamides in chicken muscle and milk samples. The proposed hybrid sorbent was easily produced from graphene oxide and a single crosslinker of ethylene glycol dimethacrylate. It gave favorable properties including uniformer structure, larger specific surface area, and enhanced column efficiency compared to the neat polymer monolith. Loading and eluting solutions affecting the on-line SPE were studied in detail. Under the optimized conditions, the on-line solid phase extraction coupled with LC-MS/MS method was achieved in 23 min. The developed method exhibited good linearity in the range of 1–100 μg/kg for sulfonamides in milk samples, and 2–200 μg/kg in chicken muscle samples, with r ranging from 0.993 to 0.999. The detection limits (S/N = 3) were 0.3 μg/kg in milk and 0.6 μg/kg in chicken muscle. The spiked recoveries were in the range of 70.3–98.5% and 79.0–108.0%, with a precision of 5.19–9.37% and 4.04–8.57%, respectively. Furthermore, the graphene oxide-incorporated monolithic sorbent allowed more than 450 extraction cycles without any loss in the extraction efficiency. The developed method was successfully applied for the determination of 16 sulfonamides in milk and chicken muscle samples.