Separation of cellulose acetates by degree of substitution

A liquid chromatographic method was developed allowing separating cellulose acetates (CA) with respect to degree of substitution (DS). The normal-phase gradient separation, which is based on an adsorption-desorption mechanism, uses a multi-step gradient of dichloromethane (DCM) and methanol (MeOH) on a bare silica column as stationary phase. Applicability of the developed multi-step gradient allows separating CAs within the DS-range DS = 1.5-2.9, which is the target DS-range for most CA applications. To the best of our knowledge the developed method for the first time allows determination of the DS-distribution of intact CA chains over a wide DS-range.