Dexamethasone is a potent glucocorticoid which acts as an anti-inflammatory and immunosuppressant for therapeutic treatments in many inflammatory and autoimmune conditions, oncology, and endocrine diseases such as Addison's disease. Dexamethasone levels in serum or plasma are measured by LC-MS/MS for dexamethsaone suppression tests or monitoring dexamethsaone treatment regimens. This Certified Spiking Solution® is suitable for use as starting materials in the preparation of calibrators and controls for dexamethasone testing methods by LC-MS/MS.