title: Development of visual peak selection system based on multi-ISs normalization algorithm to apply to methamphetamine impurity profiling.
abstract: The aim of this study is to improve resolution of impurity peaks using a newly devised normalization algorithm for multi-internal standards (ISs) and to describe a visual peak selection system (VPSS) for efficient support of impurity profiling. Drug trafficking routes, location of manufacture, or synthetic route can be identified from impurities in seized drugs. In the analysis of impurities, different chromatogram profiles are obtained from gas chromatography and used to examine similarities between drug samples. The data processing method using relative retention time (RRT) calculated by a single internal standard is not preferred when many internal standards are used and many chromatographic peaks present because of the risk of overlapping between peaks and difficulty in classifying impurities. In this study, impurities in methamphetamine (MA) were extracted by liquid-liquid extraction (LLE) method using ethylacetate containing 4 internal standards and analyzed by gas chromatography-flame ionization detection (GC-FID). The newly developed VPSS consists of an input module, a conversion module, and a detection module. The input module imports chromatograms collected from GC and performs preprocessing, which is converted with a normalization algorithm in the conversion module, and finally the detection module detects the impurities in MA samples using a visualized zoning user interface. The normalization algorithm in the conversion module was used to convert the raw data from GC-FID. The VPSS with the built-in normalization algorithm can effectively detect different impurities in samples even in complex matrices and has high resolution keeping the time sequence of chromatographic peaks the same as that of the RRT method. The system can widen a full range of chromatograms so that the peaks of impurities were better aligned for easy separation and classification. The resolution, accuracy, and speed of impurity profiling showed remarkable improvement.
authors.affiliation: Department of Computer Science and Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, Republic of Korea.
authors.forename: Hun Joo
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: College of Pharmacy, Duksung Women's University, 33, Samyangro 144-gil, Dobong Gu, Seoul, Republic of Korea; Innovative Drug Center, Duksung Women's University, 33, Samyangro 144-gil, Dobong Gu, Seoul, Republic of Korea.
authors.forename: Eunyoung
authors.initials: E
authors.lastname: Han
authors.affiliation: National Forensic Service Drug & Forensic Toxicology Division, National Forensic Service 10 Ipchun-ro, Wonju 220-170, Republic of Korea.
authors.forename: Jaesin
authors.initials: J
authors.lastname: Lee
authors.affiliation: Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon, Republic of Korea.
authors.forename: Heesun
authors.initials: H
authors.lastname: Chung
authors.affiliation: Department of Computer Science and Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, Republic of Korea. Electronic address: adstar2000@empas.com.
authors.forename: Sung-Gi
authors.initials: SG
authors.lastname: Min
mesh_terms: D000465:Algorithms; D002849:Chromatography, Gas; D004340:Drug Contamination; D005410:Flame Ionization; D053593:Forensic Toxicology / Q000379:methods*; D006801:Humans; D013287:Illicit Drugs / Q000737:chemistry*; D008694:Methamphetamine / Q000737:chemistry*
chemical_list: D013287:Illicit Drugs; D008694:Methamphetamine
keywords: Impurity profiling; Methamphetamine; Methamphetamine impurity profiling; Normalization algorithm