HPLC Separation of Neurotransmitters

The neurotransmitters dl-DOPA, creatinine, hydroxytryptophan (5-HTP), and serotonin are separated in less than 4 minutes on a short 50 mm Primesep 200 column. The HPLC separation uses a mobile phase of water, acetonitrile (MeCN, ACN) and trifluoroacetic acid (TFA) and UV detection at 250 nm. Ion-pair reagents were not needed for retention of these polar, hydrophilic compounds, instead a combination of ion-exchange and reversed-phase interactions were used.