Podkowik, B I Interference by ritodrine in GC/MS confirmation of delta-9-tetrahydrocannabinol-9-carboxylic acid in urine. [electronic resource] - Clinical chemistry Jul 1991 - 1305-6 p. digital Publication Type: Letter ISSN: 0009-9147 Subjects--Topical Terms: Chromatography, LiquidDronabinol--analogs & derivativesGas Chromatography-Mass SpectrometryHumansIonsReference StandardsRitodrine--chemistry