mass-transfer-controlled electrolyte rate constant

https://doi.org/10.1351/goldbook.M03755
In controlled-potential coulometry and related techniques, the empirically evaluated constant of proportionality defined by the equation $s_{\text{B}}=- \frac{1}{c_{\text{B}}}\ \frac{\mathrm{d}c_{\text{B}}}{\mathrm{d}t}$ where cB is the bulk concentration of the substance B, and dc B dt is the rate of change of that concentration, resulting from the consumption of B by reduction or oxidation at the working electrode.
Source:
PAC, 1985, 57, 1491. 'Recommended terms, symbols, and definitions for electroanalytical chemistry (Recommendations 1985)' on page 1501 (https://doi.org/10.1351/pac198557101491)