Publications by authors named "Beom Jun Ko"

In this study, an automated online micro-solid-phase extraction (μSPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the detection of metabolites of cannabidiol (CBD), Δ-tetrahydrocannabinol (Δ-THC), and Δ-tetrahydrocannabinol (Δ-THC), particularly 7-carboxy- cannabidiol (7-COOH-CBD), 11-nor-9-carboxy-Δ-tetrahydrocannabinol (Δ-THCCOOH), 11-nor-9-carboxy-Δ-tetrahydrocannabinol (Δ-THCCOOH), and 11-nor-9-carboxy-Δ- tetrahydrocannabinol-glucuronide (Δ-THCCOOH-glu) in urine. An instrument top sample preparation (ITSP) cartridge was introduced to increase the sensitivity toward analytes and decrease the matrix effect of the urine. LC-MS/MS analysis was performed in the multiple-reaction monitoring mode, and the analytes were separated using an Acquity UPLC HSS T3 (2.

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The accurate, precise, and robust quantification of endogenous biomarkers is a challenging task because of the presence of significantly low levels of endogenous compounds in biological samples, the absence of analyte-free matrix-matched calibrators, and sample instability due to in-vitro production or degradation of the analytes. Gamma-hydroxybutyric acid (GHB), a compound often used in drug-facilitated crimes, is a human neurotransmitter produced during both the biosynthesis and metabolism of gamma-aminobutyric acid (GABA). Evidently, proving GHB intoxication through the quantification of GHB and its metabolites in biological samples is not straightforward.

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Urine was most commonly used biological sample in drug test. To create a false-negative test result, some drug abusers were reported to submit animal urine instead of their own. So, the purpose of this study was to compare and differentiate human from animal urine (Rat 370, Pig 12, Horse 10, Cat 8, Dog 13, Cow 10, Monkey 10) samples through the uses of quantitative 1H-NMR and to find biomarkers that can be used for the discrimination of human urine from animal urine.

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To investigate herbicide metabolism, human liver microsomes were incubated with threo- and erythro-isomers of flucetosulfuron. Each isomer produced one metabolite; the metabolites were unambiguously identified as enzymatic hydrolysis products by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These metabolites were synthesized, producing white solids characterized using LC-MS/MS and nuclear magnetic resonance spectroscopy (H and C).

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A hair screening method has been developed for the detection of methamphetamine using an immunoassay analyzer (AxSYM) with a fluorescence polarization immunoassay (FPIA) technique. The method consisted of washing, cutting and digesting a hair sample (5 mg) with an enzymatic digestion solution. The digested hair sample was centrifuged, and then an aliquot of the supernatant was used to conduct the screening.

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Identification of route specific marker impurities of (S)-(+)-methamphetamine can provide us with very useful information for (S)-(+)-methamphetamine abuse criminal investigation. (1S,2S)-(+)-Chloropseudoephedrine and (1R,2S)-(-)-chloroephedrine are well known impurities of (S)-(+)-methamphetamine synthesized by metal catalyzed hydrogenation of (1R,2S)-(-)-ephedrine or (1S,2S)-(+)-pseudoephedrine. In this report (1S,2S)-1-methylamino-1-phenyl-2-chloropropane is identified as a route specific marker impurity from metal catalyzed hydrogenation method for the synthesis of (1R,2S)-(-)-ephedrine or (1S,2S)-(+)-pseudoephedrine via its chloro-derivative.

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Article Synopsis
  • A new gas chromatography-mass spectrometry (GC-MS) method has been developed for quickly screening and measuring various illicit drugs and their metabolites in urine.
  • This technique can monitor 60 different drugs commonly abused in Korea, with a focus on 24 that are most prevalent.
  • The method demonstrates strong accuracy and reliability, with low detection limits and good recovery rates, making it suitable for routine drug testing in urine samples.
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A liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method was developed and validated for the simultaneous detection and quantification of seven amphetamine derivatives (amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxy-N-amphetamine (MDA), 3,4-methylenedioxy-N-methamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), N,N-dimethylamphetamine (DMA), and N,N-dimethylamphetamine-N-oxide (DMANO)) in human urine. Seven deuterium-labeled compounds were prepared for use as internal standards to quantify the analytes. One milliliter of urine was combined with 1 mL of 0.

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Impurity profiling and classification of seized methamphetamine may play an important role in the interpretation of analytical results, the determination of the synthetic method employed, and the criminal investigations of drug traffic routes. Our study is focused on classifying seized methamphetamine samples according to the groups sorted by the types and quantities of impurities present in illicit methamphetamine samples. The samples (100mg) were dissolved in 2 mL of potassium phosphate buffer (pH 7.

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