ABSTRACT
Extractive electrospray ionization (EESI) mass spectroscopy (MS) is a dual-spray powerful and versatile analytical technique, which attracts much interest due to its advantages over conventional electrospray ionization (ESI). EESI-MS, a technique derived from ESI, was first introduced by H. W. Chen et al. In the traditional ESI process, the analytes are dissolved in solvent and delivered through a capillary. In DESI, ions are generated via the reactive collisions occurring between the neutral sample molecules and the charged particles produced by the electrospray. The mechanism of EESI in the dual-spray configuration has been clarified based on the systematic phase Doppler anemometry measurements, numeric simulations, and theoretical analysis. Quantitative EESI experiments with nonylamine as internal standard showed that EESI is capable of providing both more accurate and more precise results than secondary ESI and ESI. Chen et al. demonstrated with a homemade EESI source coupled to a linear ion trap mass spectrometer that EESI shows sensitivity similar to ESI.
