Inhibition behavior of acid phosphatase, phosphodiesterase I and adenosine deaminase as tools for trace metal analysis and speciation

Simple inhibition tests are described for acid phosphatase, phosphodiesterase I and adenosine deaminase. From 23 different metals tested, the following ions affect the enzymesʹ activity (detection limits in 0.5 ml synthetic solution): inhibition of acid phosphatase: Hg2+ (0.1 mg/l) and Cu2+ (0.7 mg/l), inhibition of phosphodiesterase I: Be2+ (8 μg/l) and Cd2+ (0.9 mg/l), activation of phosphodiesterase I: Mg2+ (3 mg/l) and Zn2+ (2 mg/l), inhibition of adenosine deaminase: Hg2+ (25 μg/l), Cu2+ (70 μg/l) and Co2+ (0.8 mg/l), respectively. For phosphodiesterase the interfering effect of inhibition and activation has been investigated. In a surface water sample, matrix effects caused by complexing agents in the organic matrix suppress the inhibition. In addition to the determination of total concentrations by instrumental analysis these effects may be used for evaluation of toxic effects and speciation of the trace elements mentioned above.