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Article

Determination of β-2 Microglobulin Levels in Plasma Using a High-Throughput Mass Spectrometric Immunoassay System

Eric E. Niederkofler,^†^‡ Kemmons A. Tubbs,^† Karl Gruber,^† Dobrin Nedelkov,^† Urban A. Kiernan,^†^‡ Peter Williams,^‡ and Randall W. Nelson*^†

Intrinsic Bioprobes, Inc., Tempe, Arizona 85281, and The Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287

Anal. Chem., 2001, 73 (14), pp 3294–3299

DOI: 10.1021/ac010143j

Publication Date (Web): May 30, 2001

†

Intrinsic Bioprobes, Inc.

‡

Arizona State University.

To whom correspondence should be addressed: Intrinsic Bioprobes, Inc., 625 S. Smith Rd., Suite 22, Tempe, AZ 85281; (tel) (480) 804-1778; (fax) (480) 804-0778; (e-mail) rnelson@intrinsicbio.com.

Abstract

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 nonspecifically 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 100 samples/h (biological fluid → data). The quantitative MSIA of β₂m levels present in human plasma samples is given as illustration.