Figure 7: Screening of a house dust extract on its regulatory influence on AChE activity. Detection of negative signals and calculation of signal areas present in the course of the product trace was performed with the ‘signal recognition’ software tool (A). Comparison of the product EIC baseline spectrum with the spectra corresponding to the negative peak areas was done with ‘spectra comparison’ tool (B,C). No significant difference of baseline spectrum to negative peak 1 spectrum was detected (B,D). A potentially enzyme regulatory substance was identified, reflected by a characteristic difference between baseline spectrum and negative area spectrum (m/z 288, C). EIC of regulatory substance revealed the concurrence of the compound´s retention time and the time point of regulation (D).