Urine Testing
Amphetamines are one of the "NIDA 5". The five drugs tested for in the standard NIDA approved drug test. Amphetamines are standardly detectable in urine for 1-3 days after use. Methamphetamines stay in the system slightly longer, 3-5 days.
The Amphetamine test is a one step competitive immunoassay that is used to screen for the presence of amphetamine in urine. It is a chromatographic absorbent device in which drug or drug metabolites in a sample compete with drug conjugate immobilized on a porous membrane for a limited number of binding sites. This test is a rapid, qualitative immunoassay for the detection of amphetamine in urine. The cutoff concentration for this test is 1000 ng/ml, as recommended by the Substance Abuse and Mental Health Services Administration and NIDA." The cutoff for GC-MS, which detects d-amphetamine and methamphetamine, is 500 ng/ml.
Source: Erowid: Amphetamine Drug Tests