SAMPLE PREPARATION OPTIMIZATION FOR THE ANALYSIS OF GLIADINS IN FOOD BY MATRIX-ASSISTED LASER DESORPTION IONIZATION TIME-OF-FLIGHT MASS-SPECTROMETRY/

Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS) of wheat gliadin extracts from disti nct types of wheat varieties displays a similar characteristic gliadin mass pattern within the 30-40 kDa range. Direct observation of this p attern in food samples was used to identify gluten gliadins in food ra pidly and easily. A modified sample preparation for gliadin analysis b y MALDI/TOF-MS has improved sensitivity of gliadin detection by a fact or of more than 50. This procedure allows the direct detection of comp lex mixtures of gluten gliadins in food sample extracts down to a conc entration of 0.01 mg ml(-1), i.e. down to levels which are toxic for c oeliac patients. This highly sensitive improved method has been also e xemplified by the facile detection of individual proteins at low conce ntrations (100-400 pmol ml(-1)). (C) 1997 by John Wiley & Sons, Ltd.