This invention relates to a method for detecting the activity of a
toxin produced by
bacteria of the families Peptostreptococcaceae or Clostridiaceae using
mass spectrometry, which comprises the following steps: a) providing a planar surface suitable for
mass spectrometry measurement, with attached affinity molecules; b) incubating the planar surface from step a) with the substrate of the
toxin to be detected, to bind the substrate to the affinity molecules; c) subsequently incubating the planar surface from step b) with a sample in which the active
toxin is to be detected, in the presence of a modification compound, and incubating it for a time sufficient for the substrate to react with the modification compound in the presence of the active toxin, if present in the sample, to form a modified substrate if the active toxin is present in the sample; d) removing the remnants of the sample; e) subjecting the (modified) substrate on the planar surface to matrix-assisted
laser desorption /
ionization, ionizing it and subsequently measuring the
mass spectrum of the (modified) substrate; f) analyzing the measured
mass spectrum, such that if the measured
mass spectrum corresponds to the non-modified substrate, the active toxin is not present, and if the measured
mass spectrum corresponds to the modified substrate or a mixture of the modified and non-modified substrate, then the active toxin is present in the sample. The invention further relates to a device for the soft landing of affinity molecule ions onto a planar surface suitable for
mass spectrometry for carrying out step a) of the above method.