The authors introduce OSPP, a disease-agnostic internal standard for neat plasma and serum proteomics, and demonstrate its use across instruments and acquisition workflows. Standardisation is critical for large-scale proteomics because it makes measurements comparable across batches, instruments and time, turning complex mass spectrometry data into reproducible biological evidence. Similar principles underpin Eliptica’s platform, including proprietary labelled internal standards and dedicated data-processing methods designed to support consistent measurements at scale.