SPECTROPHOTOMETRY OF N-COMPOUNDS 249 starting from the fnst naphthcno-aromatic skeleton concervable that is built up of condensed five-membered naphtbeno rmgs. It is based on current concepts on total ionization The presence of mono-and dmaphtheno-pyridines, mono-naphthcno-qumolmes and nnphthcno-carbazoles in oil fractions was dcmonstratcd. Besides, basrc nrtrogen concentrates were obtamcd contaunng one sulphur atom per hetcroaromatm nng system Here, combmccl applrcation of mass-and ultraviolet spectrometry before and after sclcctrve hydrogenation led to dotzulcd conclusrons regardmg then heteroaromatm nucleus. Rl%UMI? *L'autcur dmcute une mdthode d'application dc la spectrometric dc masse, pour ddtcrmmcr, dans des fractions de p&role conccntrtccs, la distrrbution dcs composes du type pyrrdmc-qumolbmc, y comprls lcur disttxbution seconclarre scion leurcaract&re naphtdniquc. Lcsrdsultatscorrespondent bren avcc ccux qu'on trouvc cn SC servant de la spectromdtnc ddns l'ultraviolct. 11 cst dgalcmcnt possrble dc detcrmmcr dc ccttc faqon lcs dlstrlbutrons lndolc-carbazolc dens dcs composds azotds concentr&s non-basiqucs. La prbencc dc pyrrtlmcs mono-ct dmapht8niqucs. de qumol6mcs mononapht&riqucs et de carbazoles naphtemques dans dcs fractions dc p6trolc a pu Btrc ddmontrdc. %USAMMENPASSUNC Zur Bestrmmung dcr Vertcllung dcr Vcrbrndungcn vom Typ Pyrrdin-Chmohn ru konzcntrmrtcn Erdi)lfraktloncn, emschhcszkclr dcrcn Vcrterlung nach naphtcmschcm Charaktcr, wurdc