Development of a Supercritical Fluid Extractor Coupled with a Time-of-Flight Mass Spectrometer for Online Detection of Extracts

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A combined apparatus of a supercritical CO₂ extractor (SFE) and a time-of-flight mass spectrometer (TOF-MS) was developed aiming at the direct analysis of extracts. A fused-silica capillary acts as both a pressure restrictor and an effluent injection nozzle into the TOF-MS. The tip of the nozzle was narrowed by melting and abrasion so that a greater pressure drop occurred at the tip. In the TOF-MS chamber, differential pumping between the main and ionization chamber kept the pressure in the ionization chamber at around 10^-3 Pa when the SFE pressure was at 9.7 to 29.4 MPa. The TOF-MS performance, a mass resolution of 263 at m/z = 146, and a sensitivity of 1.6 ng (p-dichlorobenzene) were certified by direct injection of a standard organic solution. Online detection of SFE effluent containing naphthalene, p-dichlorobenzene, phenanthrene and pyrene were successfully performed by the TOF-MS only for 48000 ionization cycles corresponding to 7.5 s.