Specific and rapid analysis of ubiquinones using Craven's reaction and HPLC with postcolumn derivatization

A new method for the analysis of ubiquinones in various samples was developed using an HPLC system with postcolumn derivatization. Craven's reaction, a specific color reaction for the analysis of ubiquinones, was used in the system. Because the reaction progressed in organic sol- vents that contained ubiquinones and ethylcyanoacetate under an alkaline condition, the selectivity for ubiquinone detection was higher than that for ubiquinone detection using the nonderivatized ultraviolet detection system at 275 nm, a system widely used for the analysis of ubiqui- nones. The new detection system can avoid the adverse ef- fects of impurities. Furthermore, it can confirm specificity by stopping the color reaction under a neutral condition. The detection limit for ubiquinone-10 was 1 ng (1.2 pmol). A good linearity for the calibration curve was observed in the range of 11.7 pmol to 11.7 nmol. To investigate the pos- sible application of this method, various samples, such as soybean capsules used as a dietary supplement and biolog- ical materials (rice as well as bovine plasma and liver sam- ples), were applied to the system and their ubiquinone contents were quantified. This method is thought to be widely and conveniently applicable for determining the level of ubiquinones because of its high selectivity for ubiquinone detection.—Shimada, H., D. Kodjabachian, and M. Ishida. Specific and rapid analysis of ubiquinones using Craven's reaction and HPLC with postcolumn derivatization. J. Lipid Res. 2007. 48: 2079-2085.