Characterization of propofol-docosahexaenoic acid conjugate by infrared spectroscopy. The infrared spectrum of the conjugate was recorded on a Perkin Elmer/2000 FT-IR. The sample was run as a thin film after evaporation of solvent. The broad, strong absorption bands at 1,750 cm-1 and 1,250 cm-1 are attributable to C=O and C–O bonds, respectively, and indicate the presence of an ester. The band at 3,030 cm-1 is characteristic of an aromatic C–H (propofol) and the band at 2,800 to 2,960 cm-1 is characteristic of aliphatic C–H bonds. No O–H absorption band was seen, indicating the absence of nonesterified propofol.