Application of ultra-high performance supercritical fluid chromatography for the determination of carotenoids in dietary supplements

A quick and simple ultra-high performance supercritical fluid chromatography-photodiode array detector method was developed and validated for the simultaneous determination of 9 carotenoids in dietary supplements. The influences of stationary phase, co-solvent, pressure, temperature and flow rate on the separation of carotenoids were evaluated. The separation of the carotenoids was carried out using an Acquity UPC2 HSS C18 SB column (150 mm × 3.0 mm, 1.8 μm) by gradient elution with carbon dioxide and a 1:2 (v:v) methanol/ethanol mixture. The column temperature was set to 35 °C and the backpressure was 15.2 MPa. Under these conditions, 9 carotenoids and the internal standard, β-apo-8′-carotenal, were successfully separated within 10 min. The correlation coefficients (R2) of the calibration curves were all above 0.997, the limits of detection for the 9 carotenoids were in the range of 0.33-1.08 μg/mL, and the limits of quantification were in the range of 1.09-3.58 μg/mL. The mean recoveries were from 93.4% to 109.5% at different spiking levels, and the relative standard deviations were between 0.8% and 6.0%. This method was successfully applied to the determination of 9 carotenoids in commercial dietary supplements.