Research On The Quantitative Analysis By Measure The Electrochemical Behavior Of The Plant Polyphenols

In the paper,a cyclic voltammetry was used for establishing a method of determining the polyphenol content in natural plants through a three-electrode electrochemistry system.Cyclic voltammetry had high accuracy,good sensitivity,fast detection,good repeatability,low detection limit and easy to generalize when it is used for determining the plant polyphenols.(1)Using electrochemical method test the electrochemical behavior of gallic acid.On the optimal optimization condition,the linear relationship between concentration of gallic acid and oxidation peak current,the limit of detection(LOD)and disturbance were tested.Results showed that there was good linearity between gallic acid and oxidation peak current when the concentration of gallic acid was 0.8×10-5mol/L to 1.6×10-5mol/L.In this case,the regression coefficient was 0.9921,the lower limit of detection of gallic acid could reach 8.76×10-8mol/L,and it ealiminated the impacts of Na+,K+,Mg2+,glucose,fructose and glycerinum on the experiment.Through multiple repeated experiments,it was verified that the experiment repeatability was good.At last,such method was used for the detection of gallic acid in the green walnut peel.The detection result showed that the gallic acid content in the green walnut peel was 6.12mg/g and the marked recovery rate was 127.02%.(2)Using electrochemical method test caffeic acid content in the caffeic acid tablet.On the optimal condition,the concentration of caffeic acid was assayed.The experimental results showed that such method had good linearity within the concentration range between 1×10-5 and 1×10-4mol/L.The regression coefficient was 0.992 and the LOD of caffeic acid measured in the experiment was 3.3×<10-8mol/L.In addition,the impacts of some common substances on the determination of caffeic acid were determined and there was no disturbance observed,indicating their impacts on the experiment were ignorable and their disturbance to the subsequent experiment was eliminated.Later,multiplicating experiments were carried out and indicated the experiment had good repeatability.At last,the above built method was used for determination of ccaffeic acid content in the caffeic acid tablet.The detection result was 19.4%,and the average recovery rate measured in the marked recovery experiment was 94.5%.(3)Electrochemical behaviors of three isomers of nitrophenol were detected using cyclic voltammetry.Owing to the difference in the nature of three isomers,the oxidation peak was obviously different,the o-NP,m-NP and p-NP peak positions were 0.873V,0.345V and-0.137V.On this basis,o-NP,m-NP and p-NP were prepared into mixed solution in proportion of 10:1:2.It was discovered that the electrochemical behavior of three isomers at this time was best,the peak position had no obvious offset and was easy to separate.Subsequently,the experimental condition of p-nitrophenol mixed solution was optimized.In the final experimental detection,three isomers had very good linear relationship,when the concentration of o-NP was 0.6×10-3 to 1.4×10-3mol/L.At last,the LOD of o-NP,m-NP and p-NP were 1.4159×10-61mol/L,2.812×10-6mol/L and 1.160×10-6mol/L.In the marked recovery test,average recovery rate was highest and RSD ? 5%.