Simultaneous determination of dopamine and 3,4-dihydroxyphenylacetic acid in mouse striatum using mixed-mode reversed-phase and cation-exchange high-performance liquid chromatography

The measurement of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) is useful for an index of dopamine turnover. We developed a simultaneous determination method for dopamine and DOPAC with high-performance liquid chromatography-fluorescence detection. Mixed-mode reversed-phase and cation-exchange column (CAPCELL PAK CR column) which contained C18 silica particles and sulfonic acid cation-exchange particles was used for the separation of 3,4-dihydroxy-l-phenylalanine, catecholamines (norepinephrine, epinephrine, and dopamine) and DOPAC. The mobile phase was optimized for factors such as pH and counter ion concentration. With a mobile phase of 15 mM sodium acetate buffer (pH 4.5), separation was achieved within 22 min. The developed method was applicable to the determination of dopamine and DOPAC in mouse striatum. The concentrations of dopamine and DOPAC in mouse striatum were 4.98 ± 0.66 and 1.00 ± 0.11 μM, respectively (n = 10).