Determination of coenzyme Q by non-aqueous reversed- phase liquid chromatography

A non-aqueous reversed-phase liquid chromatographic method for determination of coenzyme Q10 in pharmaceutical formulations has been developed. The reversed-phase system provides better reproducibility and better selectivity for the separation of coenzyme Q10 analogues and degradation products than studied normal-phase systems. Furthermore, the non-aqueous mobile phase showed a very good solubility and provides a greater variety of work-up solvents for the lipophilic formulations than aqueous mobile phases. Validation studies showed detector response linearity over a concentration range of 0.2-100 micrograms/ml. The lower limit of detection was 2 ng on-column. The intra-assay precision (relative standard deviation) for a soybean oil formulation was 2.0% (n = 11).