{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T18:03:58Z","timestamp":1789495438721,"version":"build-2803163510"},"reference-count":37,"publisher":"Public Library of Science (PLoS)","issue":"9","license":[{"start":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T00:00:00Z","timestamp":1789430400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005972","name":"Deutsche Krebshilfe","doi-asserted-by":"publisher","award":["70116073, 70116288"],"award-info":[{"award-number":["70116073, 70116288"]}],"id":[{"id":"10.13039\/501100005972","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100005972","name":"Deutsche Krebshilfe","doi-asserted-by":"publisher","award":["70116073, 70116288"],"award-info":[{"award-number":["70116073, 70116288"]}],"id":[{"id":"10.13039\/501100005972","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>Reversed-phase liquid chromatography (LC) is a major separation technique for porphyrins. We coupled C18-based LC with mass spectrometry (MS) for the detection of protoporphyrin IX (PPIX) in the context of neurosurgery, where it is used as a fluorescence marker for tumor visualisation. Here, we demonstrate advantages of the replacement of the C18 with an inert biphenyl (iBP) column, which improved separation resolution and increased detection sensitivity in LC-MS of six porphyrins (uroporphyrin I, hepta-, hexa-, and pentacarboxyporphyrin I, coproporphyrins I and III) associated with the heme biosynthesis pathway. They are of potential interest as intermediates and side products in our research on 5-aminolevulinic acid-induced fluorescence-guided neurosurgery. Porphyrins consist of conjugated \u03c0-systems which interact with aromatic stationary phases such as BP by taking advantage of \u03c0-\u03c0 stacking interactions. Carryover observed with PPIX on endcapped C18 stationary phase was reduced. This improvement was due to the reduction of non-specific adsorption on metallic surfaces from the LC instrument by using inert column hardware combined with the BP stationary phase. Passivation by chemical vapor deposition was shown to reduce non-specific adsorption in the LC system better than methods using mobile phase additives. PEEK tubing in conjunction with the iBP-column provided the best results and shortened run time. Furthermore, we present a Python-based software tool for automated data processing and analyte quantification. This work contributes to our ongoing developments of porphyrin LC-MS in blood and tissue samples from glioma patients.<\/jats:p>","DOI":"10.1371\/journal.pone.0357115","type":"journal-article","created":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T17:23:44Z","timestamp":1789493024000},"page":"e0357115","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Analysis of porphyrins from serum and the benefit of inert biphenyl columns for liquid chromatography separation"],"prefix":"10.1371","volume":"21","author":[{"given":"Moritz","family":"Unnerstall","sequence":"first","affiliation":[{"name":"Medical Faculty, University of M\u00fcnster","place":["M\u00fcnster, Germany"],"department":["Service Unit Proteomics"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manfred","family":"Fobker","sequence":"additional","affiliation":[{"name":"Clinical Laboratory, University Clinic M\u00fcnster","place":["M\u00fcnster, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrick Christian","family":"Opitz","sequence":"additional","affiliation":[{"name":"Clinical Laboratory, University Clinic M\u00fcnster","place":["M\u00fcnster, Germany"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9400-0217","authenticated-orcid":true,"given":"Lukas","family":"Helmer","sequence":"additional","affiliation":[{"name":"Medical Faculty, University of M\u00fcnster","place":["M\u00fcnster, Germany"],"department":["Service Unit Proteomics"]},{"name":"University Clinic M\u00fcnster","place":["M\u00fcnster, Germany"],"department":["Department of Neurosurgery"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5652-2105","authenticated-orcid":true,"given":"Eric","family":"Suero Molina","sequence":"additional","affiliation":[{"name":"University Clinic M\u00fcnster","place":["M\u00fcnster, Germany"],"department":["Department of Neurosurgery"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simone","family":"K\u00f6nig","sequence":"additional","affiliation":[{"name":"Medical Faculty, University of M\u00fcnster","place":["M\u00fcnster, Germany"],"department":["Service Unit Proteomics"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,9,15]]},"reference":[{"key":"pone.0357115.ref001","article-title":"How reversed-phase liquid chromatography works","volume":"31","author":"J Rafferty","year":"2013","journal-title":"MJH Life Sciences"},{"key":"pone.0357115.ref002","doi-asserted-by":"crossref","first-page":"465524","DOI":"10.1016\/j.chroma.2024.465524","article-title":"Applications of hydrophilic interaction and mixed-mode liquid chromatography in pharmaceutical analysis","volume":"1739","author":"B Wei","year":"2025","journal-title":"J Chromatogr A"},{"issue":"6","key":"pone.0357115.ref003","doi-asserted-by":"crossref","first-page":"102575","DOI":"10.1016\/j.isci.2021.102575","article-title":"Porphyrins produced by acneic Cutibacterium acnes strains activate the inflammasome by inducing K+ leakage","volume":"24","author":"K-J Spittaels","year":"2021","journal-title":"iScience"},{"issue":"6","key":"pone.0357115.ref004","doi-asserted-by":"crossref","first-page":"485","DOI":"10.3390\/jpm11060485","article-title":"Improving the Pharmacological Properties of Ciclopirox for Its Use in Congenital Erythropoietic Porphyria","volume":"11","author":"G Bernardo-Seisdedos","year":"2021","journal-title":"J Pers Med"},{"issue":"1","key":"pone.0357115.ref005","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1186\/s12866-017-1054-y","article-title":"Tapping the biotechnological potential of insect microbial symbionts: new insecticidal porphyrins","volume":"17","author":"AFC Martinez","year":"2017","journal-title":"BMC Microbiol"},{"issue":"11","key":"pone.0357115.ref006","doi-asserted-by":"crossref","first-page":"6230","DOI":"10.3390\/ijms23116230","article-title":"Detection of Porphyrins in Hair Using Capillary Liquid Chromatography-Mass Spectrometry","volume":"23","author":"M Louleb","year":"2022","journal-title":"Int J Mol Sci"},{"issue":"1","key":"pone.0357115.ref007","doi-asserted-by":"crossref","first-page":"4297","DOI":"10.1038\/s41598-024-54478-y","article-title":"Protoporphyrin IX in serum of high-grade glioma patients: A novel target for disease monitoring via liquid biopsy","volume":"14","author":"A Walke","year":"2024","journal-title":"Sci Rep"},{"key":"pone.0357115.ref008","article-title":"Protoporphyrin IX Analysis from Blood and Serum in the Context of Neurosurgery of Glioblastoma","author":"A Walke","year":"2021","journal-title":"Mass Spectrometry in Life Sciences and Clinical Laboratory. 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