Molecularly imprinted dual-function ion source for direct and sensitive ambient mass spectrometric detection of trace...

Ambient ionization mass spectrometry (AMS) has emerged as a powerful technique for rapid chemical analysis by circumventing extensive sample pretreatment. However, the sensitive detection of trace illegal additives in complex food matrices remains challenging for AMS. Herein, a novel molecularly imprinted steel sheet (MISS) ion source is reported, synthesized via coating vardenafil (VAR) imprinted polymers onto a customized steel substrate. This MISS serves dual functions: acting as a solid-phase microextraction tip for rapid and selective enrichment of VAR from medicinal liquor samples, and as an ionization substrate facilitating electrospray ionization for direct AMS analysis. Extraction from liquor samples was completed within 20 min, followed by AMS detection in just 40 s. The MISS-AMS method exhibited excellent linearity over 0.2-200 μg L^-1 (R² > 0.999), with a low limit of detection (LOD) of 0.06 μg L^-1 and limit of quantification (LOQ) of 0.2 μg L^-1. Recovery rates ranged from 92.24 to 99.28%, with relative standard deviations (RSD) below 12.11%. This innovative MISS-AMS approach holds immense potential as a rapid and sensitive method for detecting trace illegal additives in food products. This approach has promising potential for rapid and sensitive detection of other trace illegal additives in various complex food matrices.