Size-exclusion chromatography hypernated to inductively-coupled plasma and electrospray ionization mass spectrometry for the analysis of human body fluids' metalloprotein profiles

Early detection and determination of treatment response of neurodegenerative diseases is challenging due to the limited number of specific biomarkers that can be used to quantify disease state and progression. Typically, either elemental or molecular signatures are targeted, but simultaneous detection of both can be expected to yield further information and thus diagnostic potential. Here we report an approach to study elements associated with biomolecules that has the potential to identify anomalous elemental signatures linked to alterations in metalloprotein or phosphorylation patterns in human body fluids. We exploit a multidimensional analytical approach via hypernation of size-exclusion chromatography (SEC) to inductively-coupled plasma mass spectrometry (ICP-MS) and electrospray ionization mass spectrometry (ESI-MS). ICP-MS limits of detection were determined to be Mg: 29.7 nmol∙L−1, Al: 0.32 nmol∙ L−1, P: 161 nmol∙ L−1, S: 410 nmol∙ L−1, Ca: 24.3 nmol∙ L−1, Mn: 4.48 nmol∙ L−1, Fe: 3.00 nmol∙ L−1, Co: 0.37 nmol∙ L−1, Ni: 0.81 nmol∙ L−1, Cu: 0.84 nmol∙ L−1, Zn: 0.22 nmol∙ L−1, Se: 91.3 nmol∙ L−1, Sr: 3.08 nmol∙ L−1, Cd: 0.18 nmol∙ L−1, I: 96.6 nmol∙ L−1, Hg: 5.28 nmol∙ L−1 and Pb: 0.07 nmol∙ L−1. Peak deconvolution was improved via non-linear least squares fitting employing the Levenberg-Marquardt algorithm in combination with exponentially-modified Gaussians. The method was applied to the analysis of three matched cerebrospinal fluid and serum samples. Our results suggest that the simultaneous acquisition of molecular and elemental mass spectra yields additional information for data interpretation and biomarker identification.