Ampeometric determination of formate with a nickel electrode

Comparison of the amperometric response of platinum and nickel electrodes for formate showed that the sensitivity of the Pt electrode changed with time while that for Ni did not. The nickel electrode was used in a flow-injection system to monitor formate and other single-carbon species and to study the kinetics of selected reactions that produce formate. The detection limit for formate in a 30 μl sample was 0.02 mM with linear response to 7.0 mM. Rate constants for hydrolysis and hydration of chloroform, carbon monoxide, and dimethylformamide in 0.10 M NaOH solution were found to be 2.30 ± 0.05 × 10−4, 8.5 − 0.05 × 10−4, and s−1, respectively, at 25°C. Advantages of this technique are direct detection of reaction product, low detection limits, fast measurements, reduced exposure to air, and low sample volumes.