{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,8]],"date-time":"2026-08-08T04:44:17Z","timestamp":1786164257849,"version":"build-2736575974"},"reference-count":64,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,6]],"date-time":"2026-08-06T00:00:00Z","timestamp":1785974400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100007921","name":"University of Pittsburgh","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100007921","id-type":"DOI","asserted-by":"crossref"}]},{"id":[{"id":"https:\/\/ror.org\/01an3r305","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Metabolites"],"abstract":"<jats:p>Background\/Objectives: Opiates comprise naturally occurring opium alkaloids and their semisynthetic derivatives. Routine urine drug screening relies on enzyme immunoassays (EIAs) to rapidly detect opiate exposure; however, EIAs provide limited insight into opiate-associated metabolic patterns. Methods: We retrospectively analyzed liquid chromatography\u2013quadrupole time-of-flight mass spectrometry (LC-qToF-MS) datasets from comprehensive urine drug screening of 363 patients at the University of Pittsburgh Medical Center Clinical Toxicology Laboratory. Multiple statistical analyses were applied to identify the features associated with opiate (OPIA)-EIA-positive, oxycodone (OXY)-EIA-positive, and 6-monoacetylmorphine (6MAM)-EIA-positive specimens (42, 34, and seven specimens, respectively) designated as EIA-associated discovery feature sets. The feature sets selected by \u22652 statistical analyses were defined as EIA-associated consensus feature set and further evaluated using MS-FINDER for feature annotation. Results: Among 14,883 features, 138, 121, and 104 features were assigned to the OPIA-, OXY-, and 6MAM-EIA discovery feature sets, respectively. Consensus feature sets included oxycodone\/opiate metabolites, acetaminophen metabolites, and norfentanyl for OPIA-EIA; oxycodone metabolites, \u03b1-phenylalanylaspartic acid, and 4-pyridoxic acid for OXY-EIA; and norfentanyl, 6-monoacetylmorphine, and 3-hydroxycotinine artifact for 6MAM-EIA. Conclusions: These metabolomic patterns indicate a dominant exposure gradient model, in which OXY-EIA-positive specimens primarily reflect prescribed oxycodone exposure, 6-MAM-EIA-positive specimens reflect illicit heroin\/fentanyl exposure with polysubstance\/recreational use signature, and OPIA-EIA-positive specimens occupy an intermediate, mixed profile shaped by immunoassay cross-reactivity and real-world co-exposures. Associations involving \u03b1-phenylalanylaspartic acid and 4-pyridoxic acid are hypothesis-generating and require further validation. These findings illustrate the value of archived clinical toxicology datasets for metabolomic discovery and as a foundation for sentinel laboratory-based surveillance of evolving drug and chemical exposures.<\/jats:p>","DOI":"10.3390\/metabo16080558","type":"journal-article","created":{"date-parts":[[2026,8,6]],"date-time":"2026-08-06T15:52:30Z","timestamp":1786031550000},"page":"558","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Retrospective Metabolomics Profiling of Clinical Urine Drug Screen Samples Reveals Features Associated with Opiate Exposure"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6218-7892","authenticated-orcid":false,"given":"Delaney","family":"Morrow","sequence":"first","affiliation":[{"name":"Department of Pathology, University of Pittsburgh School of Medicine; Pittsburgh, PA 15261, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0779-7676","authenticated-orcid":false,"given":"Rachel K.","family":"Vanderschelden","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Pittsburgh School of Medicine; Pittsburgh, PA 15261, USA"},{"name":"Clinical Laboratories, University of Pittsburgh Medical Center Presbyterian Hospital, Pittsburgh, PA 15213, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9627-9442","authenticated-orcid":false,"given":"Kenichi","family":"Tamama","sequence":"additional","affiliation":[{"name":"Department of Pathology, University of Pittsburgh School of Medicine; Pittsburgh, PA 15261, USA"},{"name":"Clinical Laboratories, University of Pittsburgh Medical Center Presbyterian Hospital, Pittsburgh, PA 15213, USA"},{"name":"McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1007\/BF03020955","article-title":"In the arms of Morpheus the development of morphine for postoperative pain relief","volume":"47","author":"Hamilton","year":"2000","journal-title":"Can. J. Anaesth."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1038\/s41380-020-0661-4","article-title":"The changing opioid crisis: Development, challenges and opportunities","volume":"26","author":"Volkow","year":"2021","journal-title":"Mol. Psychiatry"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1016\/j.drugpo.2019.01.010","article-title":"The triple wave epidemic: Supply and demand drivers of the US opioid overdose crisis","volume":"71","author":"Ciccarone","year":"2019","journal-title":"Int. J. Drug Policy"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1007\/164_2019_260","article-title":"Newly Emerging Drugs of Abuse","volume":"258","author":"Tamama","year":"2020","journal-title":"Handb. Exp. Pharmacol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1062","DOI":"10.1124\/pharmrev.121.000506","article-title":"Oxycodone: A Current Perspective on Its Pharmacology, Abuse, and Pharmacotherapeutic Developments","volume":"75","author":"Barrett","year":"2023","journal-title":"Pharmacol. Rev."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2395","DOI":"10.1021\/acschemneuro.8b00150","article-title":"DARK Classics in Chemical Neuroscience: Morphine","volume":"9","author":"Devereaux","year":"2018","journal-title":"ACS Chem. Neurosci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2374289518811797","DOI":"10.1177\/2374289518811797","article-title":"A Difficult Challenge for the Clinical Laboratory: Accessing and Interpreting Manufacturer Cross-Reactivity Data for Immunoassays Used in Urine Drug Testing","volume":"5","author":"Krasowski","year":"2018","journal-title":"Acad. Pathol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1093\/ajcp\/aqx138","article-title":"Newly Emerging Drugs of Abuse and Their Detection Methods: An ACLPS Critical Review","volume":"149","author":"Liu","year":"2018","journal-title":"Am. J. Clin. Pathol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.cca.2020.12.010","article-title":"Advances in drugs of abuse testing","volume":"514","author":"Tamama","year":"2021","journal-title":"Clin. Chim. Acta"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1578","DOI":"10.1111\/bph.15475","article-title":"Metabolic phenotyping of opioid and psychostimulant addiction: A novel approach for biomarker discovery and biochemical understanding of the disorder","volume":"179","author":"Caspani","year":"2022","journal-title":"Br. J. Pharmacol."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Vanderschelden, R.K., Kundu, R., Morrow, D., Patel, S., and Tamama, K. (2025). Retrospective Urine Metabolomics of Clinical Toxicology Samples Reveals Features Associated with Cocaine Exposure. Metabolites, 15.","DOI":"10.20944\/preprints202507.2613.v1"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3155","DOI":"10.4155\/bio.14.260","article-title":"Metabolomics of drugs of abuse: A more realistic view of the toxicological complexity","volume":"6","year":"2014","journal-title":"Bioanalysis"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1365","DOI":"10.1002\/jat.2874","article-title":"Review: Toxicometabolomics","volume":"33","author":"Bouhifd","year":"2013","journal-title":"J. Appl. Toxicol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"706","DOI":"10.1080\/15563650.2025.2529016","article-title":"Xylazine detection in urine of fentanyl-positive patients from a single academic center","volume":"63","author":"Tamama","year":"2025","journal-title":"Clin. Toxicol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Tamama, K. (2023). Dilute and shoot approach for toxicology testing. Front. Chem., 11.","DOI":"10.3389\/fchem.2023.1278313"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1038\/nmeth.3393","article-title":"MS-DIAL: Data-independent MS\/MS deconvolution for comprehensive metabolome analysis","volume":"12","author":"Tsugawa","year":"2015","journal-title":"Nat. Methods"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"W71","DOI":"10.1093\/nar\/gkq329","article-title":"MSEA: A web-based tool to identify biologically meaningful patterns in quantitative metabolomic data","volume":"38","author":"Xia","year":"2010","journal-title":"Nucleic Acids Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"W652","DOI":"10.1093\/nar\/gkp356","article-title":"MetaboAnalyst: A web server for metabolomic data analysis and interpretation","volume":"37","author":"Xia","year":"2009","journal-title":"Nucleic Acids Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1735","DOI":"10.1038\/s41596-022-00710-w","article-title":"Using MetaboAnalyst 5.0 for LC-HRMS spectra processing, multi-omics integration and covariate adjustment of global metabolomics data","volume":"17","author":"Pang","year":"2022","journal-title":"Nat. Protoc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"W388","DOI":"10.1093\/nar\/gkab382","article-title":"MetaboAnalyst 5.0: Narrowing the gap between raw spectra and functional insights","volume":"49","author":"Pang","year":"2021","journal-title":"Nucleic Acids Res."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"e86","DOI":"10.1002\/cpbi.86","article-title":"Using MetaboAnalyst 4.0 for Comprehensive and Integrative Metabolomics Data Analysis","volume":"68","author":"Chong","year":"2019","journal-title":"Curr. Protoc. Bioinform."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"7946","DOI":"10.1021\/acs.analchem.6b00770","article-title":"Hydrogen Rearrangement Rules: Computational MS\/MS Fragmentation and Structure Elucidation Using MS-FINDER Software","volume":"88","author":"Tsugawa","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1038\/nmeth.4512","article-title":"Identifying metabolites by integrating metabolome databases with mass spectrometry cheminformatics","volume":"15","author":"Lai","year":"2018","journal-title":"Nat. Methods"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1186\/s13321-015-0087-1","article-title":"MINEs: Open access databases of computationally predicted enzyme promiscuity products for untargeted metabolomics","volume":"7","author":"Jeffryes","year":"2015","journal-title":"J. Cheminform."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1007\/s11306-007-0082-2","article-title":"Proposed minimum reporting standards for chemical analysis Chemical Analysis Working Group (CAWG) Metabolomics Standards Initiative (MSI)","volume":"3","author":"Sumner","year":"2007","journal-title":"Metabolomics"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1007\/s11306-012-0434-4","article-title":"Mass appeal: Metabolite identification in mass spectrometry-focused untargeted metabolomics","volume":"9","author":"Dunn","year":"2013","journal-title":"Metabolomics"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"117940","DOI":"10.1016\/j.trac.2024.117940","article-title":"Tips and tricks for LC\u2013MS-based metabolomics and lipidomics analysis","volume":"180","author":"Rakusanova","year":"2024","journal-title":"Trends Anal. Chem."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"705","DOI":"10.1007\/s40262-018-00731-3","article-title":"Updated Clinical Pharmacokinetics and Pharmacodynamics of Oxycodone","volume":"58","author":"Kinnunen","year":"2019","journal-title":"Clin. Pharmacokinet."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1097\/FPC.0000000000000351","article-title":"PharmGKB summary: Oxycodone pathway, pharmacokinetics","volume":"28","author":"Huddart","year":"2018","journal-title":"Pharmacogenet Genom."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1124\/jpet.123.001651","article-title":"Hydrocodone, Oxycodone, and Morphine Metabolism and Drug-Drug Interactions","volume":"387","author":"Coates","year":"2023","journal-title":"J. Pharmacol. Exp. Ther."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1016\/S0025-6196(11)60750-7","article-title":"Opioid metabolism","volume":"84","author":"Smith","year":"2009","journal-title":"Mayo Clin. Proc."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1093\/jat\/bkt031","article-title":"Prescription opioids. I. Metabolism and excretion patterns of oxycodone in urine following controlled single dose administration","volume":"37","author":"Cone","year":"2013","journal-title":"J. Anal. Toxicol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1016\/j.clpt.2006.01.009","article-title":"Pharmacokinetics and pharmacodynamics of oral oxycodone in healthy human subjects: Role of circulating active metabolites","volume":"79","author":"Lalovic","year":"2006","journal-title":"Clin. Pharmacol. Ther."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"907","DOI":"10.1111\/j.1476-5381.2010.00673.x","article-title":"The effects of CYP2D6 and CYP3A activities on the pharmacokinetics of immediate release oxycodone","volume":"160","author":"Samer","year":"2010","journal-title":"Br. J. Pharmacol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"409","DOI":"10.1093\/jat\/33.8.409","article-title":"Determination of naloxone and nornaloxone (noroxymorphone) by high-performance liquid chromatography-electrospray ionization- tandem mass spectrometry","volume":"33","author":"Fang","year":"2009","journal-title":"J. Anal. Toxicol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.forsciint.2016.02.033","article-title":"The cutting of cocaine and heroin: A critical review","volume":"262","author":"Gentile","year":"2016","journal-title":"Forensic Sci. Int."},{"key":"ref_37","unstructured":"Kane, S.P. (2026, May 04). ClinCalc DrugStats Database, Version 2025.08. Available online: https:\/\/clincalc.com\/DrugStats\/."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Li, Y.Y., Ghanbari, R., Pathmasiri, W., McRitchie, S., Poustchi, H., Shayanrad, A., Roshandel, G., Etemadi, A., Pollock, J.D., and Malekzadeh, R. (2020). Untargeted Metabolomics: Biochemical Perturbations in Golestan Cohort Study Opium Users Inform Intervention Strategies. Front. Nutr., 7.","DOI":"10.3389\/fnut.2020.584585"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"120103","DOI":"10.1016\/j.lfs.2021.120103","article-title":"Determination of metabolic phenotype and potential biomarkers in the liver of heroin addicted mice with hepatotoxicity","volume":"287","author":"Li","year":"2021","journal-title":"Life Sci."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"rkae129","DOI":"10.1093\/rap\/rkae129","article-title":"Use of over-the-counter supplements, sleep aids and analgesic medicines in rheumatology: Results of a cross-sectional survey","volume":"8","author":"Soomro","year":"2024","journal-title":"Rheumatol. Adv. Pract."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"27536130251320101","DOI":"10.1177\/27536130251320101","article-title":"Natural Product Use for Chronic Pain: A New Survey of Patterns of Use, Beliefs, Concerns, and Disclosure to Providers","volume":"14","author":"Seal","year":"2025","journal-title":"Glob. Adv. Integr. Med. Health"},{"key":"ref_42","first-page":"491","article-title":"Relationship between body store of vitamin B6 and plasma pyridoxal-P clearance: Metabolic balance studies in humans","volume":"106","author":"Lui","year":"1985","journal-title":"J. Lab. Clin. Med."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1186\/s40170-016-0151-y","article-title":"Metabolomics and metabolic pathway networks from human colorectal cancers, adjacent mucosa, and stool","volume":"4","author":"Brown","year":"2016","journal-title":"Cancer Metab."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2089","DOI":"10.1093\/carcin\/bgu131","article-title":"Fecal metabolomics: Assay performance and association with colorectal cancer","volume":"35","author":"Goedert","year":"2014","journal-title":"Carcinogenesis"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"713","DOI":"10.1093\/jn\/119.5.713","article-title":"Identification of N-beta-L-aspartyl-L-phenylalanine as a normal constituent of human plasma and urine","volume":"119","author":"Burton","year":"1989","journal-title":"J. Nutr."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"931","DOI":"10.1016\/0016-5085(86)90697-9","article-title":"Intestinal hydrolysis of aspartylphenylalanine--the metabolic product of aspartame","volume":"91","author":"Tobey","year":"1986","journal-title":"Gastroenterology"},{"key":"ref_47","first-page":"Es111","article-title":"Opioid-induced hypogonadism: Why and how to treat it","volume":"15","author":"Bellini","year":"2012","journal-title":"Pain. Physician"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"c4462","DOI":"10.1136\/bmj.c4462","article-title":"Opioid induced hypogonadism","volume":"341","author":"Reddy","year":"2010","journal-title":"BMJ"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"76","DOI":"10.1007\/s11934-016-0634-y","article-title":"Opioid-Induced Androgen Deficiency (OPIAD): Diagnosis, Management, and Literature Review","volume":"17","author":"Wosnitzer","year":"2016","journal-title":"Curr. Urol. Rep."},{"key":"ref_50","first-page":"ES145","article-title":"Opioid-induced androgen deficiency (OPIAD)","volume":"15","author":"Smith","year":"2012","journal-title":"Pain. Physician"},{"key":"ref_51","doi-asserted-by":"crossref","unstructured":"Mallappallil, M., Sabu, J., Friedman, E.A., and Salifu, M. (2017). What Do We Know about Opioids and the Kidney?. Int. J. Mol. Sci., 18.","DOI":"10.3390\/ijms18010223"},{"key":"ref_52","doi-asserted-by":"crossref","unstructured":"Gao, S., and He, Q. (2024). Opioids and the kidney: Two sides of the same coin. Front. Pharmacol., 15.","DOI":"10.3389\/fphar.2024.1421248"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1016\/j.jpain.2003.09.007","article-title":"Opioids and renal function","volume":"5","author":"Mercadante","year":"2004","journal-title":"J. Pain."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"e2350630","DOI":"10.1001\/jamanetworkopen.2023.50630","article-title":"Xylazine in Overdose Deaths and Forensic Drug Reports in US States, 2019-2022","volume":"7","author":"Cano","year":"2024","journal-title":"JAMA Netw. Open"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"3874","DOI":"10.1021\/acschemneuro.4c00583","article-title":"Classics in Chemical Neuroscience: Medetomidine","volume":"15","author":"Berida","year":"2024","journal-title":"ACS Chem. Neurosci."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"269","DOI":"10.15585\/mmwr.mm7415a3","article-title":"Notes from the Field: Severe Medetomidine Withdrawal Syndrome in Patients Using Illegally Manufactured Opioids\u2014Pittsburgh, Pennsylvania, October 2024-March 2025","volume":"74","author":"Ostrowski","year":"2025","journal-title":"MMWR Morb. Mortal. Wkly. Rep."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"672","DOI":"10.15585\/mmwr.mm7330a3","article-title":"Notes from the Field: Detection of Medetomidine Among Patients Evaluated in Emergency Departments for Suspected Opioid Overdoses\u2014Missouri, Colorado, and Pennsylvania, September 2020-December 2023","volume":"73","author":"Schwarz","year":"2024","journal-title":"MMWR Morb. Mortal. Wkly. Rep."},{"key":"ref_58","unstructured":"Tamama, K., Morrow, D., and Rates, T. (Clin. Chem., 2026). Detection of multiple medetomidine metabolites in clinical urine specimens by LC-qToF-MS, Clin. Chem., Accepted."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1038\/s41398-021-01228-7","article-title":"Metabolomics reveals biomarkers of opioid use disorder","volume":"11","author":"Ghanbari","year":"2021","journal-title":"Transl. Psychiatry"},{"key":"ref_60","first-page":"25","article-title":"The pK(a) Distribution of Drugs: Application to Drug Discovery","volume":"1","author":"Manallack","year":"2007","journal-title":"Perspect. Med. Chem."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1007\/s00216-008-1962-7","article-title":"High-performance liquid chromatography-tandem mass spectrometry in the identification and determination of phase I and phase II drug metabolites","volume":"391","author":"Holcapek","year":"2008","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"362","DOI":"10.1002\/mas.10008","article-title":"Practical implications of some recent studies in electrospray ionization fundamentals","volume":"20","author":"Cech","year":"2001","journal-title":"Mass. Spectrom. Rev."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"W127","DOI":"10.1093\/nar\/gks374","article-title":"MetaboAnalyst 2.0\u2014A comprehensive server for metabolomic data analysis","volume":"40","author":"Xia","year":"2012","journal-title":"Nucleic Acids Res."},{"key":"ref_64","doi-asserted-by":"crossref","unstructured":"Schiffman, C., Petrick, L., Perttula, K., Yano, Y., Carlsson, H., Whitehead, T., Metayer, C., Hayes, J., Rappaport, S., and Dudoit, S. (2019). Filtering procedures for untargeted LC-MS metabolomics data. BMC Bioinform., 20.","DOI":"10.1186\/s12859-019-2871-9"}],"container-title":["Metabolites"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2218-1989\/16\/8\/558\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,8]],"date-time":"2026-08-08T04:26:41Z","timestamp":1786163201000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2218-1989\/16\/8\/558"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,6]]},"references-count":64,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["metabo16080558"],"URL":"https:\/\/doi.org\/10.3390\/metabo16080558","relation":{},"ISSN":["2218-1989"],"issn-type":[{"value":"2218-1989","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,6]]}}}