Top plots showing all 45 runs, before and after alignment. These two heat-map-encoded top plots display the total ion current (TIC) for mass chromatograms of all 45 runs in a C. elegans experiment (see text), before and after alignment. Run #8 was used as the alignment reference. The brightness is proportional to the logarithm of intensity, so peaks are displayed as bright vertical bars. Initially, as the run number increases, the peaks are skewed to left, meaning the same peaks eluted earlier in higher-numbered (later) runs. The pattern also exhibits serious breaks and other nonlinearities. These imperfections were corrected by the alignment method and are not evident in the bottom image.