The challenge in the bioanalysis of coenzyme Q10 using capillary electrophoresis

TRIPODI V.,; FLOR S.,; CONTIN M.,; BOVERIS A.,; LUCANGIOLI S.

SEVILLA, ESPAÑA

Simposio; 15th Latin-American Symposium on Biotechnology, Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology; 2009

LACE

Coenzyme Q10 (CoQ10) is a lipid-soluble compound that mainly locates in the mitochondria and plays an important role as an essential electron carrier in the electron transport chain. CoQ10 is known as a powerful antioxidant agent able to protect circulating lipoproteins and cell membranes against oxidative damage. Recent reports have suggested that CoQ10 levels may be lower in certain conditions like neurodegenerative damage, Parkinson disease, alcoholism, thyroid diseases, myocardial diseases, hemodialysis, prematurity, liver diseases, hyperlipidemia, DNA damage and b-thalasemia. For these reasons, the determination of CoQ10 in plasma is important for diagnosis and the follow-up of treatment. The low concentrations of CoQ10 in plasma, the complexity of this matrix and two molecular properties necessary for CoQ10 function (the high hydrophobicity of the polyprenyl side chain and the easy oxidation of the benzoquinone ring) make the analysis of CoQ10 technically challenging. Many analytical procedures have been reported to quantitate CoQ10 in plasma: HPLC –UV or electrochemical detection, HPLC-MS and also voltammetric, chemioluminiscent, fluorimetric and spectrophotometric methods. These procedures usually require complicated pretreatment of the sample before the analysis. Liquid chromatographic method with electrochemical detection (HPLC-ECD) probably seems to be the most common for this purpose because of its high sensitivity. However, this methodology is complicated, time-consuming and it is rather used in the clinical laboratory, at least in Argentina. Capillary electrophoresis with its relevant features of performance such as simplicity, very high resolution in short times of analysis with few solvent and sample use and low cost of operation, has become an alternative methodology to the analysis of different compounds of biological interest. In the last few years, microemulsion electrokinetic chromatography (MEEKC) systems have emerged as a very attractive separation method in which the selectivity is accomplished by the partition of the analytes between a mobile phase and a pseudostationary phase together with their electrophoretic mobilities. We report the first capillary electrophoretic method based on a MEEKC system using a double tensioactive: sodium bis (2-ethylhexyl) sulfosuccinate (AOT) and cholic acid after a very simple 1-propanol / hexane extraction procedure for the determination of CoQ10 in human plasma. The optimized electrophoretic conditions included the use of an uncoted-silica capillary of 60 cm total length and 75 µm id, an applied voltage of 20 kV, room temperature and 214 nm UV detection. Selectivity, linearity, LOD, LOQ, precision and accuracy were evaluated as the parameters of validation. Our results have also been compared with the traditional EKC systems (MEKC and MEEKC with SDS), MEEKC system with AOT as the unique tensioactive and a standard HPLC method with UV detection. Due to its simplicity and reliability, the proposed method can be an adventageous alternative to the traditional methodology for the quantitation of CoQ10 in human plasma with good accuracy and precision.