 Keith U. Ingold

K. U. Ingold coauthored the 1983 study with G. W. Burton and A. Joyce comparing lipid-soluble chain-breaking antioxidant activity with independently measured vitamin E. The activity measurement used an inhibited autoxidation assay, while high-performance liquid chromatography supplied a compositional measurement.^[ref]

The scientific distinction is between how quickly a radical-trapping antioxidant intercepts reactive intermediates and how much trapping capacity a finite sample contains. Antioxidant reaction competition concerns rates; an inhibited interval can instead report a finite capacity under a specified initiation model.

For an original idealization, suppose each donor molecule intercepts $\nu$ radical events and radicals enter at constant concentration rate $R_i$. Complete interception until exhaustion givesAn observed interval of $200\mathrm{s}$ at chosen $R_i=0.10\mu \mathrm{mol}{\mathrm{L}}^{-1}{\mathrm{s}}^{-1}$ identifies capacity $\nu c_A=20\mu \mathrm{mol}{\mathrm{L}}^{-1}$. It is consistent with $c_A=10\mu \mathrm{mol}{\mathrm{L}}^{-1}$ and $\nu =2$, or $c_A=20\mu \mathrm{mol}{\mathrm{L}}^{-1}$ and $\nu =1$.

Thus timing alone does not identify molecular stoichiometry and concentration separately. A chromatographic measurement can supply independent information, provided the chemical identity and response calibration are appropriate. This is an illustrative identifiability argument, not a fitted value or individual experimental task assigned to Ingold.