Radioactive nuclides emitting b+-radiation are used for labeling in PET diagnostic. Before the radioactive labeled agent can be used, the radiochemical purity has to be determined by means of two separate radio-chromatography methods. For HPLC, TLC, GC and CE special radioactivity detectors sensitive for b+-radiation are required, which fulfil the regulations of various international and national authorities. All conventional chromatography detectors in applications of HPLC, TLC, GC and CE like UV-absorption, fluorescence, reflective index, conductivity, amperometry etc. have an analog signal output 0-1 V. Therefore all signal recording and peak integration systems for chromatography have analog inputs of 0-1 V.