The stability of synephrine stock solutions (40.0 and 80.0 mg/
mL) and of other amines (2.0 and 4.0 mg/mL) was determined on
triplicate aliquots which were kept at room temperature for 8 h.
Peak areas of these samples were compared with those of freshly
prepared stock solutions. Similarly, the stability of the same
standard solutions was assessed after storage for 20 days
at 20 C