Primary Metrologia54(3),S16 article. Verified first-author byline Blaza Toman. Only the general physical measurement model from the introduction is used: equations1–3 define RF as amount-per-response, and the discussion after equation3/equation4 establishes correlations from a shared calibration factor. The body uses a different, explicitly defined signal-per-amount convention and original numerical data; no biological samples or protocols are described.