Analysis of milkfat by HPLC

A routine method for HPLC analysis of milkfat has been developed, which takes into account the specific phenomena of this complex and far‐ranging system of triglycerides. The usual amount of injection of 1 mg has been reduced to 30 or 10 µg of fat. By this the composition of the mobile phase (acetone:acetonitrile, 35/65) and the temperature of the column (Nucleosil C18‐5 µ, 15 cm + Microspher C18‐3µ, 10 cm, in series, T=30–35 C) could be adjusted to a relatively high selectivity without inducing the high‐melting fat components to crystallize on the column. A further advantage resulting from this consisted in permitting the eluent to be recycled over long periods of time. The extremely low amounts of samples necessitated a highly sensitive detection (Δn=5 × 10−7 RI units full scale deflection) which could be realized by an interferential refractometer in connection with a thermostat to keep up a stable temperature of the whole HPLC system (ΔT