Quantitation of Ubiquinone (Coenzyme Q₁₀) in Serum/Plasma Using Liquid Chromatography Electrospray Tandem Mass Spectrometry (ESI-LC-MS/MS).

Dietary ubiquinone (Coenzyme Q10) is considered an essential co-factor in the mitochondrial respiratory chain responsible for oxidative phosphorylation. This oil-soluble vitamin-like substance is mobile in cellular membranes and plays a unique role in the electron transport chain (ETC). Coenzyme Q10 (CoQ10) is present in most eukaryotic cells and functions as an electron carrier and an antioxidant. Although the exact role of Coenzyme Q10 is often debated; there is a growing interest in the measurement of CoQ10 concentrations particularly in the area of cardiovascular disease, malignancies, exercise physiology, Parkinson's disease, and patients undergoing statin drug therapies. We describe a simple method for the quantitative measurement of the ammonium adduct of Coenzyme Q10 using a high-pressure liquid chromatography combined with positive electrospray ionization tandem mass spectroscopy (ESI-LC-MS/MS) utilizing a 3 μm PFP(2) 50 × 2.0 mm 100 Å column. A stable isotopic deuterated internal standard, in the form of Coenzyme Q10-[D9], is added to the patient serum. The extraneous proteins are precipitated from the sample with ethanol and isolation of the targeted compound is facilitated by the addition of hexane to aide in the cleanup and recovery. Quantitation occurs via a 6-point calibration that is linear from 0.16 to 6.0 μg with an observed error of 6.2 % across the analytical range.