Chapter 10: Secondary Electrospray Ionization

This chapter details the technique called extractive electrospray ionization (EESI) and describes its state-of-the-art developmental, mechanical and experimental aspects and shows its most important applications. EESI is a sensitive, matrix-tolerant secondary electrospray ionization technique, which is in the focus of ongoing investigations. The strength of EESI is its ability to ionize various compounds directly out of the sample without preparation or chromatographic separation. Although it appears to be not always the most sensitive method, it has shown enormous capabilities for various applications such as breath or skin analysis, the classification of perfumes, detection of melamine in milk and identification of the freshness of frozen meat or fruit.