Short term storage of samples containing monoamines: ascorbic acid and glutathione give better protection against degradation than perchloric acid.

In order to study the protection of monoamines from degradation during short-time storage, the effect of three different antioxidants on the degradation of dopamine, dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5-HIAA) was analyzed after 5 and 20 h. The results showed that dopamine was still quite stable after 20 h storage at room temperature, but that about 95% of 5-HIAA had disappeared. The best protection against degradation of all three substances was achieved when 15% v/v of a solution containing 1-2 mM ascorbic acid or 40 mM glutathione was added to the sample, resulting in near 100% protection after 20 h. Perchloric acid actually accelerated the degradation of 5-HIAA.