{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T22:49:17Z","timestamp":1789080557560,"version":"build-2803163510"},"reference-count":27,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,2,8]],"date-time":"2025-02-08T00:00:00Z","timestamp":1738972800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004587","name":"Instituto de Salud Carlos III","doi-asserted-by":"publisher","award":["PI24\/00688"],"award-info":[{"award-number":["PI24\/00688"]}],"id":[{"id":"10.13039\/501100004587","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004587","name":"Instituto de Salud Carlos III","doi-asserted-by":"publisher","award":["PID2022-138243OB-I00"],"award-info":[{"award-number":["PID2022-138243OB-I00"]}],"id":[{"id":"10.13039\/501100004587","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004587","name":"Instituto de Salud Carlos III","doi-asserted-by":"publisher","award":["2021 SGR 00881"],"award-info":[{"award-number":["2021 SGR 00881"]}],"id":[{"id":"10.13039\/501100004587","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100011033","name":"FEDER, European Union, \u201cA way of making Europe\u201d; Agencia Estatal de Investigaci\u00f3n","doi-asserted-by":"publisher","award":["PI24\/00688"],"award-info":[{"award-number":["PI24\/00688"]}],"id":[{"id":"10.13039\/501100011033","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100011033","name":"FEDER, European Union, \u201cA way of making Europe\u201d; Agencia Estatal de Investigaci\u00f3n","doi-asserted-by":"publisher","award":["PID2022-138243OB-I00"],"award-info":[{"award-number":["PID2022-138243OB-I00"]}],"id":[{"id":"10.13039\/501100011033","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100011033","name":"FEDER, European Union, \u201cA way of making Europe\u201d; Agencia Estatal de Investigaci\u00f3n","doi-asserted-by":"publisher","award":["2021 SGR 00881"],"award-info":[{"award-number":["2021 SGR 00881"]}],"id":[{"id":"10.13039\/501100011033","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Universitats de la Generalitat de Catalunya","award":["PI24\/00688"],"award-info":[{"award-number":["PI24\/00688"]}]},{"name":"Universitats de la Generalitat de Catalunya","award":["PID2022-138243OB-I00"],"award-info":[{"award-number":["PID2022-138243OB-I00"]}]},{"name":"Universitats de la Generalitat de Catalunya","award":["2021 SGR 00881"],"award-info":[{"award-number":["2021 SGR 00881"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Accurate quantification of indoxyl sulfate (IndS) and p-cresyl sulfate (pCS) is essential for understanding their role in chronic kidney disease (CKD) progression and for developing strategies to mitigate their harmful effects, including cardiovascular morbidity and renal fibrosis. Advances in liquid chromatography\u2013high-resolution mass spectrometry (LC\u2013HRMS) enable the integration of powerful diagnostic tools into clinical laboratories. Along with accurate quantification, precise mass measurements allow for untargeted compound identification. Methods. An LC\u2013HRMS was validated for quantifying IndS and pCS in human serum, following EMA guidelines. The method involved protein precipitation with methanol, micro-LC for chromatographic separation, and detection based on accurate mass, with simultaneous high-resolution full-scan acquisition. Clinical samples from patients with varying degrees of renal insufficiency and samples obtained before and after hemodiafiltration were analyzed. Results. The method demonstrated acceptable linearity, precision, and accuracy. The measurement range for both analytes was from 100 to 40,000 ng\/mL. Serum levels of IndS and pCS correlated with decreased renal function. After hemodiafiltration, there was a significant reduction of IndS (50%) and pCS (43%). Simultaneous untargeted analysis allowed to identify metabolites significantly underexpressed after hemodiafiltration. Conclusions. An accurate LC\u2013HRMS method was validated for the quantification of IndS and pCS serum levels in patients with CKD, providing insights into toxin dynamics and enabling untargeted metabolic evaluation.<\/jats:p>","DOI":"10.3390\/molecules30040782","type":"journal-article","created":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T11:08:51Z","timestamp":1739358531000},"page":"782","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Validation of an LC\u2013HRMS Method for Quantifying Indoxyl Sulfate and p-Cresyl Sulfate in Human Serum"],"prefix":"10.3390","volume":"30","author":[{"given":"Mar\u00eda","family":"Rodr\u00edguez-Garc\u00eda","sequence":"first","affiliation":[{"name":"Biochemistry and Molecular Genetics Department, CDB, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Irene","family":"Mart\u00ednez","sequence":"additional","affiliation":[{"name":"Biochemistry and Molecular Genetics Department, CDB, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Irene","family":"Aliart","sequence":"additional","affiliation":[{"name":"Biochemistry and Molecular Genetics Department, CDB, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2540-2578","authenticated-orcid":false,"given":"Jaime I.","family":"Sainz de Medrano","sequence":"additional","affiliation":[{"name":"Biochemistry and Molecular Genetics Department, CDB, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5667-0650","authenticated-orcid":false,"given":"Nayra","family":"Rico","sequence":"additional","affiliation":[{"name":"Biochemistry and Molecular Genetics Department, CDB, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0411-207X","authenticated-orcid":false,"given":"V\u00edctor Joaqu\u00edn","family":"Escudero-Saiz","sequence":"additional","affiliation":[{"name":"Nephrology and Renal Transplantation, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1673-0353","authenticated-orcid":false,"given":"Francisco","family":"Maduell","sequence":"additional","affiliation":[{"name":"Nephrology and Renal Transplantation, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9074-2272","authenticated-orcid":false,"given":"Manuel","family":"Morales-Ruiz","sequence":"additional","affiliation":[{"name":"Biochemistry and Molecular Genetics Department, CDB, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"},{"name":"Institut d\u2019Investigacions Biom\u00e8diques August Pi i Sunyer (IDIBAPS), 08036 Barcelons, Spain"},{"name":"Centro de Investigaci\u00f3n Biom\u00e9dica en Red de Enfermedades Hep\u00e1ticas y Digestivas (CIBERehd), 28029 Madrid, Spain"},{"name":"Department of Biomedicine, Faculty of Medicine and Health Science, University of Barcelona, 08036 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3271-1371","authenticated-orcid":false,"given":"Gregori","family":"Casals","sequence":"additional","affiliation":[{"name":"Biochemistry and Molecular Genetics Department, CDB, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"},{"name":"Institut d\u2019Investigacions Biom\u00e8diques August Pi i Sunyer (IDIBAPS), 08036 Barcelons, Spain"},{"name":"Centro de Investigaci\u00f3n Biom\u00e9dica en Red de Enfermedades Hep\u00e1ticas y Digestivas (CIBERehd), 28029 Madrid, Spain"},{"name":"Department of Fundamental and Clinical Nursing, Faculty of Nursing, University of Barcelona, L\u2019Hospitalet de Llobregat, 08907 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,8]]},"reference":[{"key":"ref_1","unstructured":"Vaidya, S.R., and Aeddula, N.R. 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