Study on Determination of Polyphenols in Water-soluble Extract of Cornus Officinalis Kernels by Folin-Ciocalteu Method

Objective The optimum conditions of Folin-Ciocalteu method for the determination of polyphenols content in the water-soluble extract of cornus officinalis kernels was studied by using gallic acid as the standard substance. Methods Absorbency was adopted as evaluation index,factors that influenced the detection performance,such as the detection wavelength,the amount of Folin-Ciocalteu reagent,the amount of sodium carbonate,reaction time and reaction temperature were investigated. Results The optimum conditions for polyphenols determination by Folin-Ciocalteu method were as follows: 1. 0 mL of Folin-Ciocalteu reagent was added in 1. 0 mL of sample,and then 3. 2 mL of 10% sodium carbonate solution was added. After the coloration reaction was for 1. 0 h at 35℃,the absorbance was measured at 760 nm.Under the optimum conditions,the absorbance increased linearly with the concentration of gallic acid in the range of 0 to 250 μg /mL( y = 0. 0053 x + 0. 0389,R2= 0. 9993). The average spiked recoveries were98. 5% ~ 103. 0% with the relative standard deviations of 1. 9% ~ 2. 3%( n = 6). The average value of polyphenols content in the water-soluble extract of cornus officinalis kernels from three batches was 39. 24%.Conclusion Folin-Ciocalteu method established in this study is simple,fast,highly sensitive and very stable. It is suitable to be applied to determine polyphenols content in the water-soluble extract of cornus officinalis kernels.