Determination of mercury(II), methylmercury and ethylmercury in the ng/ml range with an electrochemical enzyme glucose probe

Hg(II), methylmercury and ethylmercury have been determined with an electrochemical glucose probe. Mercury and its compounds inhibit the enzyme invertase which, in presence of its substrate, sucrose, produces glucose. When invertase is in presence of mercury its activity decreases; this causes a decrease of glucose production, which is monitored by the glucose sensor and correlated to the concentration of mercury in solution. Parameters such as pH, enzyme concentration, substrate concentration, and reaction and incubation time were optimized. Results showed that mercury, methylmercury and ethylmercury can be detected directly in aqueous solution in the range 2-10 ng/ml.