Deuterium distribution tools. The deuterium distribution can be extracted using the tools in the "DeutDistControl" tab in the "Manual Assessment and Validation" form (see Fig. 7). The distribution is shown as a blue bar graph overlaying the mass spectrum. Parameters for truncating the theoretical and experimental isotopic envelope are controlled by setting the relative threshold (%) or by setting the exact number of peaks to be used in the calculation (see Chik et. al ). A truncated isotopic profile can then be 'padded' using the specified number of zero-intensity peaks. The amount of deuteration can be calculated by the weighted average of the reported distribution and this is displayed within the "DeutDistControl" tab.