Time filter

Source Type

Seoul, South Korea

Aboud M.,Florida International University | Oh H.H.,Supreme Prosecutors Office | Mccord B.,Florida International University
Electrophoresis | Year: 2013

In this paper, a rapid thermal cycling procedure is combined with a direct amplification from a paper punch, permitting a high-speed amplification of a 7-locus multiplex that requires no extraction step. When coupled with a short 1.8 cm microfluidic electrophoresis system, the entire procedure from paper punch to genotype can be completed in under 25 min. The paper describes selection and optimization of enzyme, direct amplification conditions, the reproducibility of the procedure, and concordance with standard forensic genotyping methods. The procedure utilizes a small high-speed thermal cycler and microfluidic device along with a small laptop and is highly portable. Overall, this technique should provide a useful and reliable procedure for rapid determination of identity of individuals retained at checkpoints as well as a quick method for preliminary identification of individuals at remote locations following mass disasters. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chung H.,Korea University | Park J.,Korea University | Lee S.,Korea University | Kang C.,Supreme Prosecutors Office
Digital Investigation | Year: 2012

The demand for cloud computing is increasing because of the popularity of digital devices and the wide use of the Internet. Among cloud computing services, most consumers use cloud storage services that provide mass storage. This is because these services give them various additional functions as well as storage. It is easy to access cloud storage services using smartphones. With increasing utilization, it is possible for malicious users to abuse cloud storage services. Therefore, a study on digital forensic investigation of cloud storage services is necessary. This paper proposes new procedure for investigating and analyzing the artifacts of all accessible devices, such as Windows system, Mac system, iPhone, and Android smartphone. © 2012 Elsevier Ltd. All rights reserved.

Kim Y.T.,Korea Advanced Institute of Science and Technology | Lee D.,Korea Advanced Institute of Science and Technology | Heo H.Y.,Korea Advanced Institute of Science and Technology | Sim J.E.,Supreme Prosecutors Office | And 4 more authors.
Biosensors and Bioelectronics | Year: 2016

A fully integrated slidable and valveless microsystem, which performs solid phase DNA extraction (SPE), micro-polymerase chain reaction (μPCR) and micro-capillary electrophoresis (μCE) coupled with a portable genetic analyser, has been developed for forensic genotyping. The use of a slidable chip, in which a 1. μL-volume of the PCR chamber was patterned at the center, does not necessitate any microvalves and tubing systems for fluidic control. The functional micro-units of SPE, μPCR, and μCE were fabricated on a single glass wafer by conventional photolithography, and the integrated microdevice consists of three layers: from top to bottom, a slidable chip, a channel wafer in which a SPE chamber, a mixing microchannel, and a CE microchannel were fabricated, and a Ti/Pt resistance temperature detector (RTD) wafer. The channel glass wafer and the RTD glass wafer were thermally bonded, and the slidable chip was placed on the designated functional unit. The entire process from the DNA extraction using whole human blood sample to identification of target Y chromosomal short tandem repeat (STR) loci was serially carried out with simply sliding the slidable chamber from one to another functional unit. Monoplex and multiplex detection of amelogenin and mini Y STR loci were successfully analysed on the integrated slidable SPE-μPCR-μCE microdevice by using 1. μL whole human blood within 60. min. The proposed advanced genetic analysis microsystem is capable of point-of-care DNA testing with sample-in-answer-out capability, more importantly, without use of complicated microvalves and microtubing systems for liquid transfer. © 2015 Elsevier B.V.

Lee S.Y.,Kyung Hee University | Park N.-H.,Kyung Hee University | Jeong E.-K.,Kyung Hee University | Wi J.-W.,Kyung Hee University | And 4 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2012

Gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) were compared for their capacity to metabolite identification, sensitivity, and speed of analysis for propofol and its metabolites in urine samples. Acidic hydrolysis, liquid-liquid extraction (LLE), and trimethylsilyl (TMS) derivatization procedures were applied for GC/MS analysis. The LC/MS analysis used a simple sample pretreatment based on centrifugation and dilution. Propofol and four metabolites were successfully analyzed by GC/MS following TMS derivatization. One compound, . di-isopropanolphenol was tentatively characterized as a new metabolite observed for the first time in human urine. The TMS derivatization greatly improved the chromatographic properties and detection sensitivity, especially for hydroxylated metabolites. The lower limits of quantitation (LLOQ) of propofol were about 325 and 0.51. ng/mL for the GC/MS scan mode and selected ion monitoring (SIM) mode, respectively. In addition, five conjugated propofol metabolites were successfully analyzed by LC-MS/MS in negative ion mode. The detection sensitivity for these conjugated metabolites could be greatly enhanced by the addition of triethylamine to the mobile phase without any loss of LC resolution capacity. The LLOQs of propofol-glucuronide (PG) were about 1.17 and 2.01. ng/mL for the LC-MS-selected ion monitoring (SIM) and multiple reaction monitoring (MRM) mode, respectively. Both GC/MS and LC/MS methods sensitively detected nine metabolites of propofol and could be used to provide complementary data for the reasonable propofol metabolism study. Urinary excretion profiles for propofol and its metabolites following administration to human were suggested based on the total ion chromatograms obtained by GC/MS and LC/MS methods, respectively. © 2012 Elsevier B.V..

Choi Y.J.,Supreme Prosecutors Office | Sim A.,Supreme Prosecutors Office | Kim M.K.,Supreme Prosecutors Office | Suh S.,Supreme Prosecutors Office | And 2 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2016

Nonmedical use of prescription stimulants such as phentermine (PT) has been regulated by law enforcement authorities due to its euphorigenic and relaxing effects. Due to high potential for its abuse, reliable analytical methods were required to detect and identify PT and its metabolite in biological samples. Thus a dilute and shoot liquid chromatography–tandem mass spectrometric (LC–MS/MS) method was developed and validated for simultaneous determination of PT, N-hydroxyphentermine (NHOPT) and mephentermine (MPT) in urine. A 5 μL aliquot of diluted urine was injected into the LC–MS/MS system. Chromatographic separation was performed by reversed-phase C18 column with gradient elution for all analytes within 5 min. Identification and quantification were based on multiple reaction monitoring (MRM) detection. Linear least-squares regression with a 1/x2 weighting factor was used to generate a calibration curve and the assay was linear from 50 to 15000 ng/mL (PT and MPT) and 5 to 750 ng/mL (NHOPT). The intra- and inter-day precisions were within 8.9% while the intra- and inter-day accuracies ranged from −6.2% to 11.2%. The limits of quantification were 3.5 ng/mL (PT), 1.5 ng/mL (NHOPT) and 1.0 ng/mL (MPT). Method validation requirements for selectivity, dilution integrity, matrix effect and stability were satisfied. The applicability of the developed method was examined by analyzing urine samples from drug abusers. © 2016 Elsevier B.V.

Discover hidden collaborations