Study on Extraction Process of Sipunculus nudus Polysaccharide and Its Antioxidant Activity

[Objectives] This study was conducted to optimize the extraction process of Sipunculus nudus polysaccharide. [Methods]S. nudus polysaccharide was extracted by ultrasonic water extraction,with the marine S. nudus as a raw material from Sanya City,Hainan Province,by single factor variable method,to find the optimal extraction conditions including ultrasonic power,solid-liquid ratio,ultrasonic extraction temperature,ultrasonic extraction time,ultrasonic extraction times and lye concentration. The absorbance of the polysaccharide was determined by an ultraviolet spectrophotometer,and polysaccharide yield were calculated. The antioxidant activity of scavenging hydroxyl and DPPH radicals was measured at different concentrations. [Results]The optimal extraction conditions for S. nudus polysaccharide were as follows： solid-liquid ratio at 1∶11 mg/ml,extraction temperature at 60 ℃,three times of ultrasonic extraction,ultrasonic power of 960 W,extraction time of 1. 5 h,and lye concentration of 5%,under which the polysaccharide yield was 3. 21%. The scavenging rates of hydroxyl radical and DPPH radical were 12. 58% at the concentration of 0. 20 mg/ml. Moreover,the scavenging rates increased significantly with the increase of concentration. [Conclusions] This method is a new trial with satisfactory results.

Determination of Content of Amino Acid in Abalone by Precolumn Derivatization and its Nutritional Value Evaluation

[Objectives] This study was conducted to optimize the determination conditions of amino acids from abalone. [Methods] The sample was treated by acid hydrolysis method and subjected to 2,4-2 nitro fluorobenzene column derivatization. The amino acid content in abalone was determined by HLPC,and the nutritional value of the amino acids was evaluated with egg protein model put forward by Institute of Nutrition and Food Hygiene,Chinese Academy of Preventive Medicine. [Results] Abalone contains full amino acids. According to the FAO/WHO ideal,it is a high-quality protein source and suitable for supplement of protein source for human body. [Conclusions]The experimental method has simple operation and could achieve a good effect with wide linear range and correlation coefficient over 0. 999 8,and the obtained results are satisfactory.

Assessment of Different Instruments and Methods for Detecting Pollution Share Rate of Heavy Metals in Water Samples

[ Objective ] This study aimed to investigate the impacts of different instruments and methods on detection of water samples and evaluate the detection results and pollution share rate. [ Method] Concentrations of six heavy metals in three surface water samples and three underground water samples were detected by AAS and ICP-AES to analyze the differences in detection results and calculate the pollution share rate of heavy metals. [Result] As a result, the pollution share rate of six heavy metals varied significantly. Calculation results of comprehensive pollution share rate based on the lower pollution index of the same heavy metal in the same water sample detected by two methods were different from the results using either method. Due to different detection limits of instruments, detection results of heavy metals in the same water sample were different, which affected the accuracy of environmental quality assessment. [ Conclusion ] The detected pollution share rate varies with different detection limits. Therefore, instruments and methods with lower detection limit should be used. To be specific, AAS is suitable for detection of Pb and Cd, while ICP is suitable for detection of Cu, Zn, Fe and Mn.