{"entity": "researcher", "timestamp": "2026-08-23T22:11:02.260Z", "family": "Drotleff", "given": "Bernhard", "initials": "B", "orcid": "0000-0003-0914-6578", "affiliations": ["Metabolomics Core Facility, EMBL Heidelberg, 69117 Heidelberg, Germany."], "links": {"self": {"href": "https://publications-affiliated.scilifelab.se/researcher/fbdc5ca2c2dd45fc85c5ce71f4b3731e.json"}, "display": {"href": "https://publications-affiliated.scilifelab.se/researcher/fbdc5ca2c2dd45fc85c5ce71f4b3731e"}}, "publications": [{"entity": "publication", "iuid": "e4323b6f9de44e12a1f20b8904098a4a", "links": {"self": {"href": "https://publications-affiliated.scilifelab.se/publication/e4323b6f9de44e12a1f20b8904098a4a.json"}, "display": {"href": "https://publications-affiliated.scilifelab.se/publication/e4323b6f9de44e12a1f20b8904098a4a"}}, "title": "Quantification of Endogenous Steroids and Hormonal Contraceptives in Human Plasma via Surrogate Calibration and UHPLC-MS/MS.", "authors": [{"family": "Su", "given": "Min", "initials": "M"}, {"family": "Drotleff", "given": "Bernhard", "initials": "B", "orcid": "0000-0003-0914-6578", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/fbdc5ca2c2dd45fc85c5ce71f4b3731e.json"}}, {"family": "Janker", "given": "Tamara", "initials": "T"}, {"family": "B\u00fcrger", "given": "Zo\u00e9", "initials": "Z", "orcid": "0000-0003-4597-0425", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/907b16865ddc43cb93d67781f7864938.json"}}, {"family": "Kimmig", "given": "Ann-Christin S", "initials": "AS"}, {"family": "Derntl", "given": "Birgit", "initials": "B"}, {"family": "L\u00e4mmerhofer", "given": "Michael", "initials": "M", "orcid": "0000-0002-1318-0974", "researcher": {"href": "https://publications-affiliated.scilifelab.se/researcher/e4a96a39caf44d518e140e3798b0ce0e.json"}}], "type": "journal article", "published": "2025-07-01", "journal": {"title": "Anal. Chem.", "issn": "1520-6882", "volume": "97", "issue": "25", "pages": "13496-13503", "issn-l": "0003-2700"}, "abstract": "Quantifying endogenous and exogenous steroids at low concentrations in biological matrices remains a major analytical challenge. Immunoassay-based diagnostics are limited by cross-reactivity, particularly at low levels, prompting a shift toward (ultra)high-performance liquid chromatography-tandem mass spectrometry ((U)HPLC-MS/MS) for clinical applications. A key limitation for endogenous hormone quantification is the absence of a true blank matrix for external calibration. To address this, we developed a surrogate calibration method employing 1,2-dimethylimidazole-5-sulfonyl chloride (DMIS) derivatization for estrogens, enabling sensitive and selective quantification alongside nonderivatized steroids. Stable isotope-labeled surrogate calibrants and internal standards were used to achieve matrix-matched quantification within a clinically relevant range. Parallelism between analytes and surrogate calibrants was systematically verified in plasma across multiple calibration levels. The method was further optimized through the use of narrow-bore UHPLC columns and refined chromatographic conditions to enhance sensitivity and resolution for a broad analyte panel. Combined with efficient protein precipitation and 96-well plate-based solid-phase extraction, the developed assay achieves pg/mL-level quantification in human plasma with high precision and accuracy. This integrated approach uniquely combines surrogate calibration for endogenous steroids with external calibration for exogenous contraceptives, including sensitive DMIS-based derivatization for estrogens, enabling comprehensive hormonal profiling in a single run. Beyond its analytical scope, the method outlines a structured validation strategy, which is aligned with regulatory principles, and may therefore serve as a practical reference for future LC-MS/MS assays employing surrogate calibration.", "doi": "10.1021/acs.analchem.5c01912", "pmid": "40539320", "labels": [], "xrefs": [{"db": "pmc", "key": "PMC12224168"}], "notes": [], "created": "2026-08-21T11:32:38.253Z", "modified": "2026-08-21T11:32:38.388Z"}]}