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. 2014 Dec 9;14(2):441–454. doi: 10.1074/mcp.M114.040790

Fig. 3.

Fig. 3.

Low concentration range plasma assay performance of stable-isotope dilution (SID), phospholipid-depleted reverse-polynomial dilution (RPD), and nondepleted RPD calibration methods in four human plasma peptides. The boxes show the mean and standard deviation of the back calculated Quality Control sample concentration measurements. The purple box indicates the theoretical concentration value ± 15%. The red dotted line indicates the SID Lower Limit of Quantification (LLOQ) of the peptide assay and the blue dotted line represents both the RPD techniques' LLOQ. Phospholipid-depleted and nondepleted RPD calibration methods performed with the same LLOQ. RPD calibration methods showed lower relative residual error in all four peptide assays and extended the LLOQ in three assays (Table V).