Analysis of Quinones such as CoQ10 and Vitamin K

  • It requires no platinum black
  • Higher reproducibility
  • Lower running cost

We also have an application using platinum blacks.

Coenzyme Q10 and vitamin K represent a class of compounds known as quinones. As a class, quinones act as important electron donors and acceptors in a variety of biological processes. Electrochemical detection (ECD) provides a very sensitive method for analyzing this class of molecules. Eicom’s HPLC-ECD systems support the following convenient, sensitive, and stable application for quinone detection.

Previous ECD methods relied on an expensive and disposable platinum reduction column, placed between the separation column and detector cell. The chemical nature of the metallic packing material introduced an unnecessary error into the analysis. Over time, the reactive surface of the metal particles declined, inevitably leading to a loss of sensitivity. Often, this decline could be so rapid as to cause significant variations between the first and last samples when many samples had to be run during one experiment. The validity of comparing single experiments in a series of experiments that were conducted over longer periods of time was a constant concern.

Our solution does away with the reducing column entirely. Instead, we use a post-column pre-electrolysis cell (the PEC-510) to reduce the CoQ10 before it enters the electrochemical detector. The pre-electrolysis cell is significantly less prone to age-induced decreases in sensitivity and accuracy. Should any decrease in sensitivity be observed, performing the pre-electrolysis cell can be easily recovered by using the appropriate applied voltage. Using an electrolysis cell, instead of the platinum column, affords the user an additional measure of confidence in peak identification because the pre-electrolysis cell also functions as an auxiliary detector. The current can be monitored simultaneously with the signal from the main detector cell. For signals that correspond to the target compounds, a negative, or mirror image, peak coincides with the main detector’s peak.

Analytical Conditions

HPLC-ECD Eicom 700 series system equipped with Pre-electrolysis cell PEC510C
Separation Column Eicompak SC-5ODS 2.1x150mm
Flow Rate 230 μl/min
Temperature 25˚C
Applied potential +700 mV vs AgCl2 for CoQ10
+450 mV vs. AgCl2 for vitamin K
Working electrode Graphite WE-G
Detection limit vitK1 1 pg (2 fmol) at S/N=2, or 20 μl of 0.1 nM
CoQ10 2 pg (2 fmol) at S/N=2, or 20 μl of 0.1 nM
Linear range 104, 2 pg to 10 ng

Simple sample preparation

CoQ10 and related compounds can easily be extracted from any biological material with the organic solvent (such as isopropanol, hexane, etc)

Eicom’s 700 series
HPLC-ECD system

Sample data:
CoQ10 and Vitamin K

Fig. 1 –  Coenzyme Q10 standards

Fig. 2 – Vitamin K standards

  1. Simultaneous detection of CoQ10 and CoQ9 possible.
  2. Simultaneous detection of CoQ10 and vitamin K possible
  3. Detection of tocopherols (vitamin E) is also possible.

Please [sg_popup id=”226585″ event=”click”]inquire[/sg_popup] about these and other quinones.