Separation of indole-3-carbinol and condensation products of indol-3-carbinol CP1, CP2 and CP3 performed on the column Kinetex 5 μ XB-C18 100A.
Indole-3-carbinol is a natural glucosinolate known for prevention of human breast, prostate and other types of cancer and it started to be used in commercial preparations, as food supplements. However no analytical method has been proposed for quality control of nutraceuticals with this substance yet. In this paper a new high-performance liquid chromatography (HPLC) method using core–shell column for separation of indole-3-carbinol and its condensation/degradation products was developed and used for the quantitative determination of indole-3-carbinol in nutraceuticals. Separation of indole-3-carbinol, its condensation/degradation products and internal standard ethylparaben was performed on the core–shell column Kinetex 5 μ XB-C18 100A (100 × 4.6 mm), particle size 5.0 μm, with mobile phase acetonitrile/water according to the gradient program at a flow rate of 1.25 mL min−1 and at temperature 50 °C. The detection wavelength was set at 270 nm. Under the optimal chromatographic conditions good linearity of determination was achieved. Available commercial samples of nutraceuticals were extracted with 100% methanol using ultrasound bath. A 5-μL sample volume of the supernatant was directly injected into the HPLC system. The developed method provided rapid and accurate tool for quality control of nutraceuticals based on cruciferous vegetable extracts with indole-3-carbinol content. The presented study showed that the declared content of indole-3-carbinol significantly varied in the different nutraceuticals available on the market. Two analyzed preparations showed the presence of condensation/degradation products of indole-3-carbinol which were not officially declared by the manufacturer. Moreover, further two analyzed nutraceutical preparations showed absolutely no content of declared amount of indole-3-carbinol.