The different LC-MS techniques available today were developed to suit specific analytical needs and the application range covered by each one is wide, but still limited. GC amenable compounds can be all analyzed with a single GC-MS system whereas HPLC applications call for specific LC-MS instrumental arrangements. ESI, APCI, APPI, and EI are ionization techniques that can be combined with different analyzers, in single or tandem configuration, to create the ultimate system for a certain application. Once approaching LC-MS for a specific need, the fast technical evolution and the variegated...