Interface for Online Coupling of Surface Plasmon Resonance to Direct Analysis in Real Time Mass Spectrometry

The online coupling of surface plasmon resonance (SPR) with mass spectrometry (MS) has been highly desired for the complementary information provided by each of the two techniques. In this work, a novel interface for direct and online coupling of SPR to direct analysis in real time (DART) MS was developed. A spray tip connected with the outlet of the SPR flow solution was conducted as the sampling part of the DART-MS, with which the online coupling interface of SPR-MS was realized. Four model samples, acetaminophen, metronidazole, quinine, and hippuric acid, dissolved in three kinds of common buffers were used in the SPR-DART-MS experiments for performance evaluation of the interface and the optimization of DART conditions. The results showed consistent signal changes and high tolerance of nonvolatile salts of this SPR-MS system, demonstrating the feasibility of the interface for online coupling of SPR with MS and the potential application in the characterization of interaction under physiological conditions.