Use of Strata-X-C SPE cartridges allows for an aggressive organic wash of biological samples while maintaining high recoveries of amphetamines and their metabolites. In combination with LC/MS/MS, limits of quantitation (LOQ) of 0.54 ng/mL are achieved for MAMPH, HMMA, and MDMA and LOQ of 1.0 ng/mL are achieved for AMPH and MDA on Gemini C18 HPLC columns. Accuracy and reproducibility are not compromised with this simple and effective approach.