Figure 3: First experiments with iAP and AMP as substrate revealed distinct signal inconstancies in all assay traces, which could be corrected with Achroma software tool ‘chromatogram comparison’. The respective software interface comprises of fields to enter m/z ranges of two molecules of interest (Box, black solid line), e.g. m/z range 347 to 348 of assay substrate AMP (A) and internal standard (IS) m/z range 155 to 156 (B). An intensity minimum of 1 was selected for both EICs. A tolerance level can be set to monitor the output of the calculated correction (Box, dashed line). The calculation of a quotient of AMP EIC (A) and IS EIC (B) resulted in a corrected and constant EIC (C). Tolerance value is set to ±10% and is displayed in C as solid line below and above the corrected EIC.