How does the sweat patch work?
The sweat patch consists of a gauze pad covered by a protective membrane similar to that of a band-aid. The membrane has an adhesive perimeter that sticks tightly to the test subject’s skin. The sweat patch is usually worn on the subject’s upper arm. Before application, the subject’s arm is swabbed with an isopropyl alcohol rub. After the patch has been worn for approximately seven to ten days, it is removed and the gauze pad is sent to the laboratory for testing. The lab usually performs “screening tests” for several different drugs, using an immunoassay testing system. If any screening test indicates the presence of a drug, the lab performs a “confirmatory test” for that drug, using the more precise “gas chromatography / mass spectrometry” (GC/MS) testing system. If the confirmatory test finds levels of the drug above the “cutoff” the lab is using, the lab will report a positive test result. Where is the sweat patch being used? Many counties around the country use the sweat patch to
