Determination of Three Polyphenols in Sugarcane by Pressurized Capillary Electrochromatography

The method for the separation and detection of chlorogenic acid,ferulic acid and epicatechin in sugarcane was established by pressurized capillary electrochromatography(pCEC). C₁₈ capillary column with sodium dihydrogen phosphate and methanol as mobile phase were used to optimize the flow ratios,buffer salt pH,buffer salt concentration,separation voltage,flow rate and other chromatographic conditions. The results showed that mobile phase was 15.0 mmol/L NaH₂PO₄ and 12.5 mmol/L sodium heptanesulfonate(pH5.0)/methanol(50:50,V/V)at a flow rate of 0.06 mL/min. Under optimal conditions including applied voltage of 1 kV and a UV detection wavelength of 220 nm,chlorogenic acid,ferulic acid and epicatechin in sugarcane were well separated. The calibration curves for the analytes had good linearity in the range of 20~320 μg/mL with the correlation coefficients as 0.9978,0.9922 and 0.9971.The limits of detection(LOD)for the chlorogenic acid,ferulic acid and epicatechin were 0.14,0.75,and 1.65 μg/mL. The recoveries were 96.79%,100.71% and 99.01% with a relative standard deviation(RSD)were 2.82%,2.69% and 1.18%,respectively. The results showed that the method was fast,accurate and reproducible,and suitable for the separation and detection of polyphenols in sugarcane.