EXPERIMENTAL CONDITIONS FOR HPLC ANALYSIS OF ETHOXYLATED ALKYL PHENOLSURFACTANTS IN MICROEMULSION SYSTEMS .1. ISOCRATIC MODE WITH MIXED-SOLVENTS

In surfactant-oil-water phase behavior studies, especially those relat ed to enhanced oil recovery, each of the oligomers of commercial polye thoxylated non-ionic surfactants partitions in a different pattern int o the two or three phases in equilibrium, and a simple, fast, and accu rate method is required to analyze all phases. Up to now, only oil-pha se GC was relied upon to determine the partitioning without closing th e surfactant inventory. Isocratic normal phase HPLC with a ternary mob ile phase (n-heptane-chloroform-methanol 70-10-20) is shown to comply with these requirements to analyze the oligomer distribution in microe mulsion, excess oil, and excess water phases of an optimum formulation system.