A novel fiber-spray/mass spectrometry method using a piece of a porous hollow fiber is described. An adapter, fabricated by a 3D-printer, was designed to connect the fiber and a standard ESI (electrospray ionization) needle, in which a Taylor cone was formed and the resulting ions were detected by a mass spectrometer. Since a porous hollow fiber is usually used for microextraction, the so-called hollow fiber liquid-phase microextraction (HF-LPME) method, a new methodology that involves coupling HF-LPME and fiber-spray, was developed for the first time. We report herein on the design and testing of a microextraction kit. The kit consists of a centrifuge tube (reservoir for the sample solution) and a piece of a porous hollow fiber (for sample extraction). The kit was placed between the mass inlet and the ESI needle. Using the kit, analytes can be extracted from a very dilute solution and then evaporate and escape from the fiber surface. When they make contact with the ESI plume, which arises from the ESI needle tip, the molecules are ionized and then detected by a mass spectrometer. Using the setup, it was possible to improve the limit of detection after microextraction by ∼360-fold when 3,4-MDMA (3,4-methylenedioxymethamphetamine) was analyzed, and the limit of detection achieved was 2 ng/mL.
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