Determination of 8 Flavonoid Compounds in Tartary Buckwheat Shell by Capillary Electrophoresis after Pre-Column Derivatization

About 1 g of tartarybuck wheat shell sample was extracted with 5 mL of 80% (volume fraction, the same below) ethanol solution at 70℃ for 2 h by stirring, and the mixture was filtered by 0.22 μm filtering membrane. The filtrate was bathed at 80℃ water bath for 30 min to remove the enzyme, and then reacted with of 2.0×10^-4mol·L^-1 BSTFA solution in a 80℃ water bath for 30 min for derivatization of the 8 flavonoid compoundsi.e. catechins (Cat), rutin (Rut), kaempferol (Kae), quercetin (Mel), hyperin (Hyp), isoquercitrin (Hir), myricetin (Myi), quercetin (Que) in the extract. DB-624 column was selected as stationary phase, and 15 mmol·L^-1 borate solution (pH 9.3) containing 15 mmol·L^-1 β-CD was used as running buffer solution. It was shown by results that fast and efficient baseline separation and determination can be obtained within 9 min for the derivatives of 8 flavonoid compounds under the optimized conditions. Linear relationships between concentrations of the 8 flavonoid compound derivatives and their respective peak areas were kept within the certain ranges, with detection limits (3S/N) in the range from 0.022 mmol·L^-1 to 0.039 mmol·L^-1. The spiked recovery test was made at the 2 concentration levels using the tartary buckwheat shell sample as matrix, giving values of recovery in the range of 99.1%-101%, with RSDs (n=5) of determined values were ranged from 1.3% to 3.2%. The 5 flavonoid compounds were detected in the tartary buckwheat shell sample, and their values of the mass fraction found were in the range of 3.35-5.19 mg·kg^-1.