title: Effect of freezing on the concentration of drugs of abuse in urine.
abstract: Benzoylecgonine, 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-acid), phencyclidine, codeine, morphine, amphetamine, methamphetamine, and lysergic acid diethylamide were dissolved in urine, stored frozen in plastic tubes at -16 to -18 degrees C, defrosted, transferred to other tubes, and analyzed by gas chromatography/mass spectrometry (GC/MS); no significant loss of compound was observed, except for THC-acid, which showed an average loss of 11%, ranging from 0 to 34% of the total concentration. The loss is attributed to the decrease in solubility of the compound and to adherence to the side of the container during freezing.
authors.affiliation: Navy Drug Screening Laboratory, Norfolk, VA 23511-2597.
authors.forename: B D
authors.initials: BD
authors.lastname: Paul
authors.forename: R M
authors.initials: RM
authors.lastname: McKinley
authors.forename: J K
authors.initials: JK
authors.lastname: Walsh
authors.forename: T S
authors.initials: TS
authors.lastname: Jamir
authors.forename: M R
authors.initials: MR
authors.lastname: Past
mesh_terms: D005615:Freezing; D006801:Humans; D013287:Illicit Drugs / Q000652:urine*; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D013287:Illicit Drugs