Publications by authors named "Carl K Horn"

Liquid chromatography-tandem mass spectrometry (LC-MS-MS) offers specific advantages over gas chromatography-mass spectrometry (GC-MS) such as the ability to identify and measure a broader range of compounds with minimal sample preparation. Comparative analysis of LC-MS-MS versus GC-MS was performed for urinalysis detection of five benzodiazepine compounds currently part of the Department of Defense (DoD) Drug Demand Reduction Program (DDRP) testing panel; alpha-hydroxyalprazolam, oxazepam, lorazepam, nordiazepam and temazepam. In the analyses of internally prepared control urine samples at concentrations around the DDRP administrative decision point for benzodiazepines (100 ng/mL), both technologies produced comparable results with average accuracies between 99.

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Performance of the Roche Online KIMS (kinetic interaction of microparticles in solution) benzodiazepine (BZD) immunoassay (IA) with and without beta-glucuronidase treatment was evaluated on a Hitachi Modular automated IA analyzer calibrated using nordiazepam at 100 ng/mL. Reproducibility, linearity, accuracy, sensitivity, and interferences were evaluated. Precision of the assay (percent coefficient of variation (%CV)) with and without addition of the enzyme was less than 6% and 9%, respectively, with linearity (r(2) value of 0.

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The purpose of this study was to evaluate the ability of two amphetamine class screening reagents to exclude ephedrine (EPH), pseudoephedrine (PSEPH), and phenylpropanolamine (PPA) from falsely producing positive immunoassay screening results. The study also sought to characterize the prevalence and concentration distributions of EPH, PSEPH, and PPA in samples that produced positive amphetamine screening results. Approximately 27,400 randomly collected human urine samples from Navy and Marine Corps members were simultaneously screened for amphetamines using the DRI and Abuscreen online immunoassays at a cutoff concentration of 500 ng/mL.

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A rapid and sensitive solid-phase extraction method for the lysergic acid diethylamide (LSD) metabolite 2-oxo-3-hydroxy-LSD (O-H-LSD) was developed for use in a forensic laboratory. The method uses a positive-pressure manifold anion-exchange polymer-based solid-phase extraction with subsequent analysis by liquid chromatography-mass spectrometry (LC-MS). The average extraction efficiency was 92%.

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A novel extraction and derivatization procedure for the cocaine metabolite benzoylecgonine (BZE) was developed and evaluated for use in a high-volume forensic urine analysis laboratory. Extractions utilized a Speedisk 48 positive pressure extraction manifold and polymer-based cation-exchange extraction columns. Samples were derivatized by the addition of pentafluoropropionic anhydride and pentafluoropropanol.

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To facilitate analysis of high sample volumes, an extraction, derivatization and gas chromatographic-mass spectrometric analysis method was developed to simultaneously determine amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxyamphetamine (MDA) 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA) in urine. This method utilized a positive-pressure manifold cation-exchange polymer-based solid-phase extraction followed by elution directly into automated liquid sampler (ALS) vials. Rapid derivatization was accomplished using heptafluorobutyric anhydride (HFBA).

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2-Oxo-3-hydroxy lysergic acid diethylamide (O-H-LSD), a major LSD metabolite, has previously been demonstrated to be a superior marker for identifying LSD use compared with the parent drug, LSD. Specifically, O-H-LSD analyzed using liquid chromatography-mass spectrometry has been reported to be present in urine at concentrations 16 to 43 times greater than LSD. To further support forensic application of this procedure, the specificity of the assay was assessed using compounds that have structural and chemical properties similar to O-H-LSD, common over-the-counter products, prescription drugs and some of their metabolites, and other drugs of abuse.

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