Online coupling of size exclusion chromatography to capillary-enhanced Raman spectroscopy for the identification of protein classes in hemolyzed blood serum

The analysis of serum for biomarkers is a standard method in clinical diagnosis and health assessment. The application of Raman spectroscopy to probe biomarkers in serum is increasingly investigated due to its time- and cost-efficiency. However, time-consuming sample preparation is often required to analyze the serum samples. Additionally, hemolyzed samples are commonly discarded due to interference in the measurements. This study focuses on the application of the online coupling of size exclusion chromatography (SEC) to diode array detector (DAD) and capillary-enhanced Raman spectroscopy (CERS) for direct analysis of hemolyzed serum samples. We demonstrate that different protein classes such as serum albumin and immunoglobulin G (IgG) can be identified in hemolyzed serum according to a calculated hit quality index (HQI). Additionally, different oxidation and binding states of the heme prosthetic group are investigated at 532-nm excitation. The online coupling of SEC-DAD-CERS enables the detailed characterization of blood serum proteins, including the differentiation of IgG, serum albumin, and hemoglobin.