REMPI, analytical method

An alternative to chemical ionisation is resonant (and non-resonant) laser ionisation methods [179], i.e. selective and soft laser photoionisation, such as REMPI. A particularly interesting setup is the combination of REMPI with TOFMS for monitoring coffee brew headspace. This chapter deals with technical features and applications of time-resolved analytical methods with particular focus on PTR-MS and resonant and laser ionisation methods (REMPI-TOFMS). 

Czech Republic). Development and application of semipermeable membrane devices (SPMDs) as environmental dosimeters for PCB contaminants in water, air, sediment, and soil is the subject of ongoing research by Huckins and Petty at Columbia Environmental Research Center in Missouri. Also at the Columbia Environmental Research Center, C. Orazio et al. are developing analytical methods for determining PCBs in environmental matrices. A reliable method for continuous monitoring of PCBs in incinerator stack gas emissions using resonance-enhanced multiphoton ionization spectroscopy in conjunction with time-of-flight mass spectroscopy (REMPI/TOFMS) is the topic of current research by... 

REMPI) is due to a successive absorption of two or more laser photons. The sum of the photon energies must exceed the ionisation energy. REMPI is the most sophisticated form of photoionisation, where the wavelength of an excitation laser is varied such that a second photon (from the same or another laser) ionises only when the first photon is resonant with a specific molecular level. This provides a combination of optical spectroscopy and mass spectrometry (i.e. a 2D analytical method). The intensity... 

Fig. 15.14 Analytical techniques for time-resolved headspace analysis. An electronic nose can be used as a low-cost process-monitoring device, where chemical information is not mandatory. Electron impact ionisation mass spectrometry (EI-MS) adds sensitivity, speed and some chemical information. Yet, owing to the hard ionisation mode, most chemical information is lost. Proton-transfer-reaction MS (PTR-MS) is a sensitive one-dimensional method, which provides characteristic headspace profiles (detailed fingerprints) and chemical information. Finally, resonance-enhanced multiphoton ionisation (REMPI) TOFMS combines selective ionisation and mass separation and hence represents a two-dimensional method. (Adapted from [190])...

APLl was developed in 2005 [68]. It is a soft ionization method with easy-to-interpret spectra for nonpolar aromatic substances and only minor tendency for fragmentation of the analytes. APLI is based on the resonance-enhanced multiphoton ionization (REMPI), however, at AP. The REMPI method allows the sensitive and selective ionization of numerous compounds. Here, for example, the following approach is used ... 

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