Rice were grounded into rice powder by muller and soaked in mixed acid solution (concentrated nitric acid:concentrated sulphuric acid=3∶2) for 12 hours. Then, the mixture was heated slowly in a hood, and mixed acid solution and aqueous hydrogen peroxide solution were added for the digestion. In order to test the trace amount cadmium in rice with square wave stripping voltammetry method, a three-electrode system are used with the silver-based mercury film electrode as working electrode, platinum electrode as counter electrode, and saturated calomel electrode as reference electrode. The results show that a good linear relationship can be obtained in pH=3.0 NH4Cl（0.2 mol/L）substrate solution, within the concentration of cadmium 0.01~ 0.12 μg/mL; the regression equation was Ip=497.59c+15.324 with the correlation coefficient of 0.994 1, the detection limit of 4.607 4×10-3 μg/mL, the relative standard deviation of 4.12%~5.56%, and the recovery rate of 90.26%~98.16%.

Nonterminal olefin of C ₁₃~C ₁₄ and maleic anhydride were used as raw materials to prepare alkenyl succinic anhydride (ASA) in a probe reaction. SO ₄ ^2-/TiO ₂ solid acid catalyst was used to synthesize ASA. The catalytic activity and stability of the catalyst were studied. The yield was quantitatively analyzed by gas chromatography. The results show that SO ₄ ^2-/TiO ₂ catalyst has high activity and good stability in the synthesis of ASA. The optimum conditions are as follows: the calcination temperature of catalyst is 550 ℃, reaction temperature is 190 ℃, reaction time is 5 h, the amount of catalyst is 1% compared with reactant total mass, the molar ratio of nonterminal olefin and anhydride is 3∶1, and the amount of antioxidant 2,6-di-tert-butyl-p-cresol is 0.5% compared with reactant total mass. The yield of ASA reaches 46.8% in the optimum conditions.