Coupling of micro solid-phase extraction with electrospray ionization and its potential for complex sample analyses using a miniature mass spectrometer

The coupling of micro solid-phase extraction (μSPE) with mass spectrometry (MS) was reported and coupled with a miniature mass spectrometer for the first time. μSPE is a promising pretreatment technique that can purify the matrix and extract target analytes in complex samples. With the online combination of μSPE with MS, the concentrated analytes eluted from the μSPE cartridge were directly ionized via electrospray ionization (ESI) and introduced into the mass spectrometer for detection. After optimization, ion intensities of drugs in saliva and rhodamine B in chili powder were enhanced 145 to 214-fold and 74 to 170-fold, respectively. The limit of quantitation (LOQ) was 2 ng/mL for drugs and 1 ng/mL for rhodamine B. Moreover, the μSPE was also coupled online with a miniature mass spectrometer, which improved the sensitivity of the miniature mass spectrometer more than 10 times. The combination of μSPE and MS significantly improved the detection sensitivity and identification capability for complex sample analyses. As a convenient and compact device, μSPE could enhance the analytical performances of mini-MS, and would benefit its field applications.