Test Catalog Search Home Test Catalog Search Testing Choices: From the standard to the extraordinary × Search Clear Filter by: Clear all Method(s) Enzyme-Linked Immunosorbent Assay (ELISA) (2) Enzyme Immunoassay (EIA) (1) (-) Gas Chromatography (GC) (2) Gas Chromatography/Mass Spectrometry (GC/MS) (4) Headspace Gas Chromatography (GC) (2) High Performance Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS) (2) High Performance Liquid Chromatography/ Tandem Mass Spectrometry (LC-MS/MS) (1) Sample Type Blood (1) (-) Serum or Plasma (1) (-) Urine (1) Test Area Therapeutics (2) Test Category Antiparkinsons (2) Test Sub-Category Anticholinergics (2) Test Test Name 4680SP Trihexyphenidyl, Serum/Plasma 4680U Trihexyphenidyl, Urine