Functional analysis of gas chromatographic data for C‐4 through C‐18:2 fatty acids

Abstract

The problem of finding a functional relationship between concentration and output data from GC has been considered for a series of fatty acids (FA). The concentrations used are relative values, i.e., the actual concentration of a FA divided by that for an internal standard. The GC output used is relative peak areas, i.e., the integrated chromatograrn area of the FA divided by that for the internal standard. Five functions have been investigated, each in reasonable accord with the concept of relative response factors being constant for a homologous series of compounds. We conclude that one of the five, C i = aAib, is clearly superior and recommend its use in agreement wRh a liferature report for different compound types (5). In the equation above, "C" and "A" are the relative concentrations and areas, respectively, and "a" and "b" are fitting constants determined from the data by least-squares minimization. We found it was impossible to deal with a matrix of 10 acids and 9 concentrations in a manner that would reproduce the data within the experimental uncertainty (6%), and we concluded that an acid-by-acid analysis was preferable.