Infinite dilution binary diffusion coefficients D-12 and retention factors k have been measured in supercritical carbon dioxide for the long-chain triglyceride triarachidonin at 313.2 K at (10 to 30) MPa, and trierucin and trinervonin both at 308.2 K to 323.2 K over the pressure range from (9 to 30) MPa by the chromatographic impulse response method. It was found that the D12 predictive correlations proposed previously, D-12/T as a function of viscosity and the Schmidt number correlations, were valid for such long-chain triglycerides having molecular weights near or over 1000. Furthermore, partial molar volumes of the solutes were determined from the relationships between k and CO2 density.