{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T09:18:43Z","timestamp":1788427123039,"version":"build-2803163510"},"reference-count":19,"publisher":"Walter de Gruyter GmbH","license":[{"start":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T00:00:00Z","timestamp":1788393600000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec id=\"j_cclm-2026-0893_abs_001\">\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>Accurate quantification of M-proteins is important for clinical management of monoclonal gammopathies. Reliable assessment of trueness on M-protein quantification in External Quality Assessment (EQA) schemes is difficult due to the lack of reference methods and materials for target value assignment. We propose a strategy to produce targeted synthetic M-protein EQA materials by spiking known amounts of human(ised) therapeutic monoclonal antibodies (t-mAb) into null serum. This paper validates homogeneity, commutability, and stability of these materials.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_cclm-2026-0893_abs_002\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Homogeneity was assessed on two aliquoted synthetic M-protein EQA materials comparing within-vial variation with between-vial variation for sodium, total protein, IgG and M-protein quantification. Commutability was assessed by comparing between-method differences in 51\u00a0patient-derived and nine synthetic M-protein EQA materials among various M-protein quantification methods. Stability was checked by reanalysis of two previously distributed synthetic M-protein EQA materials.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_cclm-2026-0893_abs_003\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Within- and between-vial variation were similar in both samples, and therefore homogeneity criteria were met. Commutability was observed for eight out of nine samples, whereas one hypergammaglobulinemic sample was non-commutable. Long-term storage stability at\u00a0\u221280\u202f\u00b0C was found acceptable in both samples.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"j_cclm-2026-0893_abs_004\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Due to their proven homogeneity, commutability, and stability, targeted synthetic M-protein EQA materials are suitable for use in M-protein EQA schemes. This allows for the assessment of laboratory performances based on target values, and opens the way for harmonisation and exchangeability of M-protein diagnostic methods. Additionally, it provides a new source for the production of M-protein EQA materials, alleviating the demand for large volumes of patient material needed to organise M-protein EQA schemes.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1515\/cclm-2026-0893","type":"journal-article","created":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T08:56:21Z","timestamp":1788425781000},"source":"Crossref","is-referenced-by-count":0,"title":["Validation of synthetic M-protein materials for external quality assessment: homogeneity, commutability, and stability"],"prefix":"10.1515","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-7717-252X","authenticated-orcid":false,"given":"Moniek M.","family":"Bioch","sequence":"first","affiliation":[{"name":"SKML, Foundation for Quality Assessment in Medical Laboratory Diagnostics , Nijmegen , The Netherlands"},{"name":"Department of Laboratory Medicine , Radboudumc , Nijmegen , The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Theo","family":"Rispens","sequence":"additional","affiliation":[{"name":"Sanquin Research , Amsterdam , The Netherlands"},{"name":"Amsterdam Institute for Infection and Immunity , Amsterdam , The Netherlands"},{"name":"Amsterdam UMC, Location Vrije Universiteit Amsterdam, Molecular Cell Biology and Immunology , Amsterdam , The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Corrie M.","family":"de Kat Angelino","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine , Radboudumc , Nijmegen , The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anke J.","family":"ten Haaken-Meijer","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine , Radboudumc , Nijmegen , The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Miranda","family":"van Berkel","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine , Radboudumc , Nijmegen , The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1771-669X","authenticated-orcid":false,"given":"Marc H.M.","family":"Thelen","sequence":"additional","affiliation":[{"name":"SKML, Foundation for Quality Assessment in Medical Laboratory Diagnostics , Nijmegen , The Netherlands"},{"name":"Department of Laboratory Medicine , Radboudumc , Nijmegen , The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joannes F.M.","family":"Jacobs","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine , Radboudumc , Nijmegen , The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"374","published-online":{"date-parts":[[2026,9,3]]},"reference":[{"key":"2026090308555080033_j_cclm-2026-0893_ref_001","doi-asserted-by":"crossref","unstructured":"Bianchi, G, Anderson, KC. 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