| A new method for analysing the contents of metallic elements, such as As, Cd, Cr, Hg, Pb, and Zn, in Porphyra haitanensis by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) was developed. Three representative areas were chosen at Qi-Dong (Jiangsu province), Xiang-Shan (Zhejiang province), and Fu-Ding (Fujian province) to collect the samples. The samples were dried to constant weight. The wet digestion used as traditional method for algae samples had problems such as time-consuming, incomplete digestion, reagent wasting, elements loss and environmental pollution. The digestion processing procedures involved two steps in this experiment, being first decomposed by standing digestion, and then by microwave digestion at different temperature gradient (100℃,180℃,100℃) each for 10 min. It was found that, the light yellow transparent digestive juice was obtained with no solid residue. It needed less digestion time, less doses of reagent with little wastes. This method was suitable for heavy metal detection in Porphyra haitanensis.Standard curve method was used as quantification of samples; the interference was eliminated by the digestion solvent. This method showed satisfactory precision and accuracy with the RSDs between 0.35% and 5.14%. Samples were random selected from each sample site and added standard solution of 6 elements respectively for recovery of standard, the results showed that recovery rates of As, Cd, Cr, Hg, Pb and Zn were between 95.8% and 105.3%, 89.0%-98.0%, 93.0%-103.2%, 90.5%-96%, 86.5 %-107.5% and 94.7%-98.4%, respectively. The analysis results also showed that the contents of some elements in three areas exceeded the limit of national standard (GB19643-2005/GB2762-2005). This method was simple, fast, and has the advantage of analyzing many elements simultaneously. The accurate analytic results provided a basic for the future researches on metallic elements removal technology.The study analysed the change of content of Cr,Cd,Pb,As(total& inorganic arsenic)in Porphyra haitanensis before and after ultrasonic treatment, based on ICP-OES and silver salt method of GB/T5009.11-2003. Using the orthogonal design to study the time, temperature, treatment method on influence of removal rate. The orthogonal experiment results showed that the optimum condition (ultrasonic frequency was 25Hz, interval treatment) of each heavy metal is as follows, removal of Cr: 10min, 45℃; removal of Cd and Pb: 20min, 35℃; removal of total arsenic: 20min, 45℃; removal of inorganic arsenic: 20min, 45℃. Removal rates were 75.7%, 63.5%, 92.1%, 90.8%, 68.8% respectively. Content of Cr,Pb,As was qualified conforming to national standard except the content of Cd, after treatments by ultrasonic. This method had the advantages of simple process and small technical difficulty, with high removal rate.
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