Selectivity coefficients and tolerance values for different SPEs.

Interferenta (10−3 M)	log K
	SSMb			MPMc
	Sensor 1	Sensor 2	Sensor 3	Sensor 1	Sensor 2	Sensor 3
KCl	−2.62	−2.75	−2.82	—	—	—
CaCl2	−2.85	−2.95	−3.05	—	—	—
MgCl2	−2.42	−2.55	−2.62	—	—	—
NaCl	−2.62	−2.84	−2.87	—	—	—
NiCl2·6H2O	−3.25	−3.33	−3.55	—	—	—
Glucose	—	—	—	−2.97	−3.36	−3.47
Urea	—	—	—	−2.40	−2.65	−2.70
Glycine	—	—	—	−3.39	−3.57	−3.72
Sucrose	—	—	—	−3.02	−3.11	−3.21
Citric acid	—	—	—	−2.87	−2.96	−3.04

^aAll interferents are at a concentration of 1 × 10⁻³ mol L⁻¹.

^bSSM: separate solution method.

^cMPM: matched potential method.