has member peak group 2018-07-19 Changed definition, relaxed restriction. [Allotrope] A common example is for alkanes such as heptanes. Often all of the isomers (C7H16, CH3CH2(CH3)C4H10, C2H5CH2(CH3)C3H8, CH3CH2(CH2CH3)C3H8, etc) are reported as a single value. Sum of all peak areas in the group. A peak group is a user defined set of peaks for which summed peak facet data is expected. [Allotrope] peak group peak peak list