1) Institute of Groundwater Ecology, Helmholtz Zentrum Muenchen, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany, 2) Thermo Fisher Scientific, Hanna-Kunath Str. 11, 28199 Bremen, Germany Rapid Communications in Mass Spectrometry (2012), V26, pp1053–1060, doi: 10.1002/rcm.6199 Gas chromatography/isotope ratio mass spectrometry of recalcitrant target compounds: performance of different combustion reactors and strategies for standardization Sandra Reinnicke (1), Dieter Juchelka (2), Sibylle Steinbeiss (1), ArminMeyer (1), Andreas Hilkert (2) and Martin Elsner (1) Compound-specific isotope analysis (CSIA) relies on continuous flow combustion of organic substances to CO2 and N2 in a miniature reactor to measure 13 C/12C and 15N/14N stable isotope ratios. Accurate analysis is well established for many volatile hydrocarbons. In contrast, compounds which contain hetero and halogen atoms are less volatile and may be more recalcitrant to combustion. This study tested carbon and nitrogen isotope analysis of atrazine, desethylatrazine (DEA), dichlobenil and 2,6-dichlorobenzamide (BAM) by gas chromatography/isotope ratio mass spectrometry (GC/IRMS) with multiple reactor tubes of two different kinds (conventional CuO/NiO/Pt and a NiO tube/CuO-NiO reactor prototype).