A Certified Spiking Solution® suitable as an internal standard for quantitation of vilazodone levels in urine or other matrices by LC/MS or GC/MS for pharmaceutical research, clinical toxicology, or forensic testing applications. Vilazodone, marketed as the antidepressant drug Viibryd®, is a new serotonin reuptake inhibitor approved by the FDA on January 21, 2011, for treatment of major depressive disorder.