title: Clinical evaluation of Toxi.Prep: a semiautomated solid-phase extraction system for screening of drugs in urine.
abstract: A prototype Toxi.Prep (TP) system that utilizes solid-phase extraction (SPE) has been developed as a method for broad-spectrum drug screening and identification of tetrahydrocannabinol (THC) metabolites in urine. TP can simultaneously extract up to seven specimens while automating the process of sample extraction, washing, and elution onto a chromatogram. TP was compared with the Toxi. Lab A (TL-A) system for extraction of basic drugs only. In a blind study, 33 distinct drugs and metabolites were detected in 55 urines over 13 runs. Of the drug occurrences, 68.8% (141 of 205) were detected on both TP and TL-A. Of the 13 runs, quinidine and quinine, nortriptyline metabolites, and diphenhydramine were noted more frequently on TP than TL-A, whereas nicotine and metabolites, morphine, and methadone metabolites were more frequently noted on TL-A. Twenty specimens were analyzed for THC metabolites. Of the cases positive for THC metabolites, 100% (16 of 16) were positive by both methods. Time and motion studies for all runs proved an overall labor reduction for extraction and spotting by approximately 40%.
authors.affiliation: Johns Hopkins Medical Institutions, Baltimore, MD 21287-7065, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Steinberg
authors.forename: L J
authors.initials: LJ
authors.lastname: Sokoll
authors.forename: K C
authors.initials: KC
authors.lastname: Bowles
authors.forename: J H
authors.initials: JH
authors.lastname: Nichols
authors.forename: R
authors.initials: R
authors.lastname: Roberts
authors.forename: S K
authors.initials: SK
authors.lastname: Schultheis
authors.forename: C M
authors.initials: CM
authors.lastname: O'Donnell
mesh_terms: D000328:Adult; D002648:Child; D002855:Chromatography, Thin Layer / Q000295:instrumentation / Q000379:methods; D013759:Dronabinol / Q000378:metabolism / Q000652:urine*; D006801:Humans; D015203:Reproducibility of Results; D015813:Substance Abuse Detection / Q000295:instrumentation* / Q000379:methods
chemical_list: D013759:Dronabinol