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. Author manuscript; available in PMC: 2008 Sep 24.
Published in final edited form as: Anal Chem. 2007 Jun 28;79(15):5878–5887. doi: 10.1021/ac0701738

Figure 5.

Figure 5

Endogenous cysC in CSF was quantitated through the use of a truncated form of cysC (trunccysC) as an internal standard. Several identical samples of CSF were spiked with the internal standard at concentrations ranging from 0.16–1.3 μM. These samples were applied to separate immunosensors to obtain SAMDI spectra in (A). Integration of the peak areas provides a quantitative measure of the ratio of the cysC to the internal standard (B). The assay at 0.49 μM (C) and 0.24 μM internal standard (D) was performed on different days, using monolayers having a range of density of the aza/Ni2+ ligand 0.5% (—), 1% (---), and 4% (…). The comparison of the peak ratios in the SAMDI spectra show the assays were highly reproducible.