Analysis of cysteinyldopas, dopa, dopamine, noradrenaline and adrenaline in serum and urine using high-performance liquid chromatography and electrochemical detection.

The catecholic amino acids, dopa, 2-S- and 5-S-cysteinyldopa, and 2,5-S,S-dicysteinyldopa were determined qualitatively in serum from patients with malignant melanoma by reversed-phase high-performance liquid chromatography, using electrochemical detection. In urine the catecholamines dopamine, noradrenaline and adrenaline were also determined qualitatively, as well as the above-mentioned compounds, in a single chromatographic run. The conditions were optimized by changing the pH of the mobile phase and by the addition of methanesulphonic acid. A comparison was made between the performance of four commercial reversed-phase packing materials containing chemically bonded octadecyl groups, using a standard mixture of catecholic amino acids. The influence of ionic strength, pH and amount of methanesulphonic acid on retention was investigated.