. 1998 Apr;116(4):1393–1401. doi: 10.1104/pp.116.4.1393

Table I.

Selectivity coefficients for the Cd²⁺-selective vibrating microelectrode

Interfering Ion (Jⁿ⁺)	Log K^pot_KJ
Zn²⁺	−2.9
Pb²⁺	−4.6
Cu²⁺	−4.8
Mn²⁺	−5.2
Fe²⁺	−8.6
Ni²⁺	−10.4
Ca²⁺	−10.8
Mg²⁺	−12.2
NH₄⁺	−6.2
Na⁺	−7.1
K⁺	−7.9

Cd²⁺ microelectrodes were back filled with 100 mm KCl, front filled with Cd²⁺ sensor, and then conditioned in 100 mm KCl overnight. Calibration curves were generated for each of the cations listed below to demonstrate that the electrode had a Nernstian response for these interfering ions in the absence of Cd²⁺. A calibration curve for Cd²⁺ was then generated. Selectivity coefficients were calculated from a general formula based on the Nicolsky-Eisenman equation (see Methods).