The oxidation of isoprene in the earth atmosphere can be separated in a high NOx pathway and a low NOx pathway. ISOPOOH (isoprene hydroxy hydroperoxide) and as a further result IEPOX (isoprene epoxidiol) are the pristine isoprene oxidation products. Previous experiments have shown, that ISOPOOH converts on metal surfaces to methyl vinyl ketone (MVK) and methacrolein (MACR) [Rivera-Rios et al., 2014]. As a consequence, standard versions of commercial SRI-ToF-MS (Selective Reagent Ion Time of Flight Mass Spectrometer) detected ISOPOOH as MVK or MACR and the experimental results were incorrect. Confronted with this problem, we developed a novel prototype of SRI-ToF-MS without metal surfaces in the drift tube, the Funnel SRI-ToF-MS. [Rivera-Rios et al., 2014] describes ISOPOOH conversion on metal surfaces to methyl vinyl ketone or methacrolein and formaldehyde. In this master thesis I come to the conclusion that a diol with the chemical formula C5H10O2 and a hydroxy carbonyl with chemical formula C5H8O2 are also created by ISOPOOH conversion on metal surfaces. I also show that chemical ionisation of ISOPOOH using H3O+ and NO+ primary ions leads to massive fragmentation. In ambient air measurements the fragments can interfere. A new primary ion mode is thus of high importance to detect ISOPOOH without fragmentation.