Abstract:

Enrichment effects of heavy metal ions on urease-catalyzed reaction were investigated with micro-calorimetry. The effects of heavy metal ions inject order, flow rates(0.1, 0.5 and 1 mL/min) and micro-particle diameters(0.5-0.6, 0.7-0.8 and 0.9-1.0 mm) on urease-catalyzed reactions inhibited by heavy metals were investigated experimentally based on flow injection analysis(FIA) method. Furtherly, some optimal conditions such as inject volumes of urease and heavy metal ions were also obtained. The results showed that a better thermal reaction signal could be detected for a low flow rate of 0.1 mL/min, micro-particle diameters of 0.5—0.6 mm, and urease and heavy metals inject volume are 3 and 5 mL, respectively. The inhibition effects as following: As³⁺>Cu²⁺> Cd²⁺> Pb²⁺. These results indicate that the micro-calorimetry may be a potential method to rapidly and accurately detect heavy metals when the detected heavy metal ions are enrichment appropriately.

Key words: Micro-calorimetry, Enrichment, Enzyme inhibition, Heavy metal ion, Inhibition rate