Strategies to expand the applicability of LC/MS to the analysis of non-polar compounds are presented within this thesis: The most important techniques presented here are on-line electrochemical conversion of the analytes to more polar reaction products, atmospheric pressure electron capture negative ion-MS and coordination ionspray-MS. These techniques are presented in detail, compared and discussed critically with respect to their current status and future perspectives. Particular focus is directed from a chemical point of view on the substance groups which are accessible by each of the new approaches