Portable Miniature\nMass Spectrometry for Enhanced\nOn-Site Detection of Analytes in Complex Samples by Integrating Solid-Phase\nMicroextraction and Nano-Electrospray Ionization

On-site mass spectrometry (MS) analysis\nplays a crucial\nrole in\ntimely understanding chemical compositions of field samples but presents\na challenge to miniaturization, portability, and sensitivity. In this\nwork, a portable MS approach was developed by integrating biocompatible\nsolid-phase microextraction (SPME) and a nano-electrospray ionization\n(nESI) emitter into a kit to couple miniature MS (mMS). The SPME fiber\nwas used for on-site extractive sampling of analytes from complex\nliquid samples and living organisms and was then inserted into an\nnESI emitter for on-site MS analysis via the facile kit. The limit\nof detection was found to be at the pg/mL level for various compounds\ntested. Acceptable relative standard deviation (RSD) values (5.5–7.6%, <i>n</i> = 6) were obtained for direct measurement of analytes\nin complex matrixes; acceptable linear responses (0.1–50 ng/mL)\nand matrix effects (76.0–82.6%) were also found. Enhanced detection\nof compounds of interest in various real samples, such as food samples,\nhuman fluids, environmental water, and living organisms, was unambiguously\ndemonstrated. Our experimental data showed that SPME-nESI-mMS is a\npromising tool for on-site analysis of various complex samples in\nsignificant applications including but not limited to food safety,\nenvironmental monitoring, forensic investigation, and bioanalysis.