A novel functionalized covalent organic framework/carbon nanotube composite as an effective online solid-phase extraction sorbent for simultaneous detection of 33 steroid hormones in pork.

A novel functionalized covalent organic framework/carbon nanotube composite (CNT@COF) was synthesized by covalent bonding and exhibited large surface area, good crystallinity and chemical stability, and high adsorption capacity for steroid hormones. Therefore, online solid-phase extraction using CNT@COF as the adsorbent coupled with Q/Orbitrap mass spectrometer was applied to simultaneously detect 33 steroid hormones in pork samples. The characterization, chemical stability and adsorption capacity of the CNT@COF sorbent were investigated, and the effects of sorbent amount and extraction velocity on the online SPE efficiency were optimized. The low limits of quantitation were in the range of 0.02-0.30 μg kg, and the reliable recoveries were between 82.12% and 116.49%. Using the validated method, hydrocortisone and estriol in two samples were positively screened at trace levels. The established method was sensitive and efficient for simultaneous detection of multiclass steroid hormones in animal-derived food.