To safeguard analytical performance of qCCP methods, careful attention to the pre-analytical phase is needed for specimen collection, transport, storage and stability. In particular for protein biomarker panels, guide lines should furthermore be established that address the specific issues related to qCCP applications, e.g., the selection of robust and quantotypic peptides as surrogates for the single protein biomarker. These special CCP guidelines should also consider the pre- analytical steps of sample preparation and protein digestion. The LC–MS/MS analysis should include implementation of the traceability concept , adequate calibration with commutable standards,normalization with stable isotopically labelled standards, and proper use of internal quality control(IQC) samples and rules, as well as control of chromatographic and MS performance. Analytical quality specifications for qCCP methods should be rationalized and pre-defined, e.g., according to the Stockholm Conference Hierarchy [35]. In addi- tion, post-analytical quality requirements for qCCP methods should particularly include traceable reference intervals and clinical decision limits, if feasible. Furthermore, external qual- ity assessment (EQA) scheme-organizers should adapt their EQA-schemes to enable testing of all major critical steps in MS-based quantitative proteomics. In addition, EQA-providers should evaluate protein standardization and harmonization efforts by means of commutable EQA-materials for all types of body fluids.