{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,22]],"date-time":"2026-07-22T18:23:58Z","timestamp":1784744638720,"version":"3.55.0"},"reference-count":41,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,6,6]],"date-time":"2023-06-06T00:00:00Z","timestamp":1686009600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Science and Technology Council (Taipei, Taiwan)","award":["MOST 110-2113-M-037-012"],"award-info":[{"award-number":["MOST 110-2113-M-037-012"]}]},{"name":"National Science and Technology Council (Taipei, Taiwan)","award":["MOST 109-2113-M-037-008"],"award-info":[{"award-number":["MOST 109-2113-M-037-008"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Herein, we used isotopic formaldehyde and sodium cyanoborohydride via reductive amination to label two methyl groups on primary amine to arrange the standards (h2-formaldehyde-modified) and internal standards (ISs, d2-formaldehyde-modified) of tryptophan and its metabolites, such as serotonin (5-hydroxytryptamine) and 5-hydroxytryptophan. These derivatized reactions with a high yield are very satisfactory for manufacturing standards and ISs. This strategy will generate one or two methyl groups on amine to create different mass unit shifts with 14 vs. 16 or 28 vs. 32 in individual compounds for biomolecules with amine groups. In other words, multiples of two mass units shift are created using this derivatized method with isotopic formaldehyde. Serotonin, 5-hydroxytryptophan, and tryptophan were used as examples to demonstrate isotopic formaldehyde-generating standards and ISs. h2-formaldehyde-modified serotonin, 5-hydroxytryptophan, and tryptophan are standards to construct calibration curves, and d2-formaldehyde-modified analogs such as ISs spike into samples to normalize the signal of each detection. We utilized multiple reaction monitoring modes and triple quadrupole mass spectrometry to demonstrate the derivatized method suitable for these three nervous biomolecules. The derivatized method demonstrated a linearity range of the coefficient of determinations between 0.9938 to 0.9969. The limits of detection and quantification ranged from 1.39 to 15.36 ng\/mL.<\/jats:p>","DOI":"10.3390\/molecules28124580","type":"journal-article","created":{"date-parts":[[2023,6,7]],"date-time":"2023-06-07T02:02:15Z","timestamp":1686103335000},"page":"4580","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Assisted Reductive Amination for Quantitation of Tryptophan, 5-Hydroxytryptophan, and Serotonin by Ultraperformance Liquid Chromatography Coupled with Tandem Mass Spectrometry"],"prefix":"10.3390","volume":"28","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1437-177X","authenticated-orcid":false,"given":"Shih-Shin","family":"Liang","sequence":"first","affiliation":[{"name":"Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan"},{"name":"Institute of Biomedical Science, College of Medicine, National Sun Yat-sen University, Kaohsiung 80424, Taiwan"},{"name":"Research Center for Precision Environmental Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan"},{"name":"Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4556-1648","authenticated-orcid":false,"given":"Po-Tsun","family":"Shen","sequence":"additional","affiliation":[{"name":"Protein Chemistry Core Laboratory, Core Instrument Center, National Health Research Institutes, Miaoli 35053, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu-Qing","family":"Liang","sequence":"additional","affiliation":[{"name":"Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi-Wen","family":"Ke","sequence":"additional","affiliation":[{"name":"Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chieh-Wen","family":"Cheng","sequence":"additional","affiliation":[{"name":"Bachelor Program in Industrial Technology, College of Future, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi-Reng","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Biotechnology, School of Environment and Life Sciences, Fooyin University, Kaohsiung 83102, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/BFb0027496","article-title":"Basic mechanisms and local modulation of nerve impulse-induced secretion of neurotransmitters from individual sympathetic nerve varicosities","volume":"112","author":"Stjarne","year":"1989","journal-title":"Rev. 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