Stability of domoic acid in saline dosing solutions

Studies designed to assess the effects of repeated low doses of domoic acid require an assessment of its stability in solution under the conditions used for in vivo studies. The stability of 1 mg/mL solutions of domoic acid in saline, with or without ascorbic acid, was determined for 15 weeks. Solutions were refrigerated, but warmed to room temperature for several hours each working day to simulate conditions of actual use. The solutions of domoic acid showed no evidence of decomposition as evidenced by stability of UV absorbance spectrum, concentration of domoic acid as determined by a liquid chromatographic method, and the chromatographic elution pattern. The addition of ascorbate to the domoic acid/saline solution did not alter the stability, but was deemed unnecessary because of the firm stability of the domoic acid/saline solution.