Fig. 2. Quantification approach provides high prediction accuracy at micromolar resolution of raw sample concentrations.

(A) Quantification of serum zinc concentrations for all four single-donor samples tested, evaluated at 56 min. Zinc concentration in chelex-treated samples was measured with inductively coupled plasma–mass spectrometry (ICP-MS), and defined zinc standards were added to each sample to achieve a range of concentrations. Serum from donors 1 to 3 was used in initial calibration, and serum from donor 4 was only used in test validation, indicated by the asterisk. Symbols falling inside the horizontal bars that correspond with the binned prediction ranges for each y-axis level indicate that the CFE test accurately quantified zinc in the serum sample. (B) Error quantification of all individual donor samples via the QEM. Low QEM for correct predictions and high QEM for incorrect predictions indicate unambiguously interpretable test results for a given time. (C) Error quantification in nonideal reaction conditions with serum from donor 4.