ELISA microplate: a viable immunocapture platform over magnetic beads for immunoaffinity-LC-MS/MS quantitation of protein therapeutics?

Evaluate the performance of ELISA microplates versus commonly used magnetic beads for biological sample cleanup and/or enrichment in immunoaffinity-LC-MS/MS to reduce tedious beads washing procedures and a relatively high assay cost. ELISA microplates were used as immunicapture platform and compared with magnetic beads for sample cleanup for LC-MS/MS quantitation of protein therapeutics. One unmodified and two surface-activated microplates provided comparable linear ranges and sensitivities for a therapeutic protein (mass 78 kDa) using a human serum sample of 100 µl with 1:1 dilution compared with Tosylactivated magnetic beads using 200 µl of human serum without sample dilution. The assays' precision and accuracy were all within acceptable ranges. No nonspecific binding or other selectivity issues were observed. The results suggested an ELISA microplate could be a viable immunocapture platform for immunoaffinity-LC-MS/MS quantitation of protein therapeutics.