This gas chromatographic method is for determining the composition of overhead stream samples from the production of UOP inhibitors. These samples typically consist of a ketone, the corresponding alcohol and other impurities. The ketone and alcohol pairs separated by this method are: methyl hexyl ketone-methyl hexyl carbinol (MHK-MHC), methyl isoamyl ketone-methyl isoamyl carbinol (MIAK-MIAC), ethyl amyl ketone-ethyl amyl carbinol (EAK-EAC), methyl ethyl ketone-methyl ethyl carbinol (MEK-MEC), and methyl isobutyl ketone-methyl isobutyl carbinol (MIBK-MIBC). Other sample components or group classifications may include light ends, unknowns, water, xylenes and low boiling intermediates. The lower limit of detection for a compound or group is 0.1 mass-%.