Determination of β-2 microglobulin levels in plasma using a high-throughput mass spectrometric immunoassay system

A high-throughput mass spectrometric immunoassay (MSIA) system for the analysis of proteins directly from biological fluids is reported. A 96-well-format robotic workstation equipped with antibody-derivatized affinity pipet tips was used for the parallel extraction of specific proteins from samples and subsequent deposition onto 96-well arrayed matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) targets. Interferences:from nonspecificalIy bound proteins were minimized through choice of appropriate affinity pipet tip derivatization chemistries, Sample preparation for MALDI-TOFMS was enhanced through the use of hydrophobic/hydrophilic contrasting targets, which also presented functionalities found to promote matrix/analyte crystal growth, Automated mass spectrometry was used in the unattended acquisition of data, resulting in an analysis rate of similar to 100 samples/h (biological fluid --> data). The quantitative MSIA of beta (2)m levels present in human plasma samples is given as illustration.