A simple procedure for the extraction of the native chromophore of visual pigments: the formaldehyde method.

The chromophore of visual pigments was efficiently extracted in its original isomeric conformation by dichloromethane/hexane in the presence of excess formaldehyde. This new method of extraction (the formaldehyde method) in combination with HPLC is useful for the determination of the chromophore composition of visual pigments. The chromophore isolated by this method is biologically active and can be used for regeneration experiments.