Diagnosis of occult blood in human feces using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry

Background: Guaiac-based chemical tests may be the most cost-effective for routine screening of fecal occult blood (FOB). Unfortunately, such approaches still suffer from the unreliability of the incidence of false-positive and false-negative results in subjects who are on an unrestricted diet. We developed a rapid, automatic, and reliable detection method for FOB using matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS). Methods: The water-soluble alpha- and beta-chain hemoglobins (Hb), which are the most predominant proteins found in blood, were used as protein biomarkers for the diagnosis of FOB. The saturated 4-hydroxy-alpha-cyanocinnamic acid (alpha-CHC) solution was found to be the best MALDI matrix for Hb analysis. Results: The MALDI-TOF MS results were consistent with those provided through conventional chemical analysis, however, the sensitivity for the detection of FOB when using MALDI-TOF MS is approximately 10-100 times higher. In addition, the materials that commonly interfere with the conventional chemical assaying of FOB do not interfere with the detection of the Hb biomarkers during MALDI-TOF MS analysis. Conclusions: We demonstrate that MALDI-TOF MS analysis of Hb biomarkers is an alternative approach toward the rapid diagnosis of FOB. (c) 2007 Elsevier B.V. All rights reserved.