Efficient adsorption and detection of steroid hormones in foods through the combination of novel magnetic TAPB-COF materials with click isotope probes.

Matrix effects pose a significant challenge in food analysis for the quantitative analysis of complex food samples. Herein, a novel magnetic covalent organic framework nanocomposite and the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction-based stable isotope labeling (SIL) method were presented for highly selective and sensitive detection of steroid hormones in food samples using HPLC-MS/MS. The nanocomposite, Fe₃O₄@TAPB-COF, with a core-shell structure exhibited high adsorption capacities for steroid hormones. Combined with a SIL method based on the CuAAC click reaction, steroid hormones were accurately quantified in food samples with high sensitivity and selectivity. A pair of SIL agents, N-(2-azidoethyl)aniline (d₀-NAEA) and d₅-N-(2-azidoethyl)aniline (d₅-NAEA), was synthesized to label steroid hormones in the samples and standard solutions, respectively. The labeling reaction is highly specific, and the formation of the derivatives is easily ionized by MS, thus overcoming matrix effects. More surprisingly, the ionization efficiency of steroid hormones increased by a factor of 4 to 56, with matrix effects ranging from 87.3 to 99.3%. Under optimal conditions, this method exhibited a low limit of detection (LOD) ranging from 0.1 to 2.6 μg L^-1 and overcame the interference of matrix effects for trace-level steroid hormone analysis in foodstuffs.