Through the method of initial heat release rate, the kinetic property of tyrosine oxidation catalyzed by tyrosinase from Pseudomonas maltophilia was investigated using a LKB-2107 batch microcalorimeter. Tyrosine was catalyzed and oxidized into L-dopa, then into melanin catalyzed by tyrosinase. We found that the tyrosinase reaction obeyed the Michaelis-Menten kinetics, and at 298.15K and pH 7.0, the initial exothermic rate (Ω0) are in the range of 0.1567～0.5704mJ·s-1, the maximum exothermic rate (Ωmax) are in 0.4152～0.8143mol·L-1, and mean value of the Michaelis constant (Km) is 2.199 0.105×104 mol L-1.

Nickel in electrolytic manganese was separated and concentrated on Chromosorb-107 resin packed in a syringe to retain the analyte. The sample solution was drawn though the resin and discharged back manually at about 20mL min-1 flow rate. Then, the analyte was" eluted by drawing and discharging with suitable eluent at a similar flow rate. Nickel was quantitatively retained.from the sample solution at pH≥6 and could be eluted by drawing and discharging 3.0mol L-1 HNO3. The validation of the method was made though the analysis of the standard reference material (SRM) AME 2003 electrolytic manganese. The recoveries of nickel in electrolytic manganese samples were in the range of 98.3-103.5%, and the precision was" characterized with relative standard deviations (RSDs) between 2.3 and 3.0%.