FAST AMPEROMETRIC FIA PROCEDURE FOR HEAVY METAL DETECTION USING ENZYME INHIBITION

The inhibition effect of heavy metals ions such as Hg(II), Cu(II), V(V), and Ni(II) on the activity of oxidase enzymes such as alcohol oxidase, glycerol 3-P oxidase, and sarcosine oxidase has been studied and used for the construction of calibration curves in flow-injection analysis. A platinum-based H2O2 probe was used to measure the enzymatic activity of the selected oxidase enzymes. The most sensitive detection system was obtained using the glycerol 3-P oxidase/Hg(II) couple. A calibration curve was obtained in the 0.05–0.4 ppm range, with a detection limit of 0.05 ppm, and a 50% of inhibition (I50) of 0.2 ppm. The enzyme alcohol oxidase was used to construct calibration curves for Cu(II) and V(V). The detection limits were 2 and 0.5 ppm, respectively, with I50 ppm for cu(II) and 2.7 ppm for V (V). Ni(II) was detected in the 1–6 ppm range, using the enzyme sarcosine oxidase; I50 was 3.8 ppm. Relative standard deviations were =5% for each enzyme/ion metal couple. The analytical behavior was comparable to measurements in batch analysis.