DETERMINATION OF MERCURY AT THE PICOGRAM PER MILLILITER LEVEL USING IMMOBILIZED HORSERADISH-PEROXIDASE

New test method and test device for the mercury (II) determination at the pg/mL level were developed based on the mercury inhibitory on horseradish peroxidase immobilized on solid supports - in the cells of the polystyrene plate and on the chromatographic paper. The reactions of o-dianisidine, 3,3',5,5'-tetramethylbenzidine and o-phenylenediamine oxidation by hydrogen peroxide were used as the indicator reactions. The mercury inhibitory effect increased in the presence of thiourea. Under the elucidated optimal conditions the calibration curves for the mercury determination showed a linear relationship between the peroxidase inhibition degree and the mercury concentration in the range of 0.1-1000 pg/mL. The mercury detection limits were 0.1-10 pg/mL independence on the concrete indicator reaction. The analysis completed in 15 min. The proposed test device was applied to the mercury determination in underground waters of Moscow region. The mercury content obtained was coincident with that obtained by atomic-fluorescent method with cold vapour.