Using multi-step high performance liquid chromatography (HPLC) it was possible to prepare a chromatographically pure sample of N@C60. Invoking EPR spectroscopy of solid samples prepared after each HPLC step, the increase of relative N@C60 concentration could unambiguously be determined. The UV/Vis spectrum of N@C60 is indistinguishable within experimental error from that of C60, confirming negligible coupling between nitrogen in its atomic ground state and C60 cage molecular wave functions. The observed large dipolar width of the EPR spectrum of the pure paramagnetic compound indicates weak spin exchange between neighboring paramagnetic centers which is further proof for a very small spin transfer from the encapsulated atom to the fullerene cage.