Analysis of coenzyme Q10 in human plasma by column-switching liquid chromatography

A new method of determining coenzyme Q(10) in human plasma was developed based on column-switching high performance liquid chromatography (HPLC). CoQ(10) was quantitatively extracted into I-propanol with a fast one-step extraction procedure, after centrifugation, the supernatant was cleaned on an octadecyl-bonded silica column and then transferred to reversed-phase column by a column-switching valve. Determination of CoQ(10) was performed on a reversed-phase analytical column with ultraviolet detection at 275 urn and the mobile phase containing 10% (v/v) isopropanol in methanol at a flow-rate of 1.5 ml/min. The sensitivity of this method allows the detection of 0.1 mug/ml CoQ(10) in plasma (S/N = 3). The linearity between the concentration and peak height is from 0.05 to 20 mg/l. The reproducibility (R.S.D.%) of the method is less than 2% (within day) and less than 3% (between day), the average recovery is 100.9 + 2.1%, it takes only 30 min to complete an analysis procedure, suitable for the determination of CoQ(10) in human plasma especially for batch analysis in clinical laboratories. Finally, the method was applied to determine the plasma CoQ(10) levels in healthy subjects, hyperthyroid and hypothyroid patients. (C) 2004 Elsevier B.V. All rights reserved.