Hanna Instruments

The HI-4014 potassium ion selective electrode is a potentiometric half-cell sensor housed within an epoxy body. The internal elements are isolated from the sample by an organic polymer sensing membrane. This liquid membrane sensor requires a separate reference electrode to complete the measurement system.

Hanna’s liquid membrane half-cell ISEs are designed for use with the HI-5315 reference half-cell. The reference half-cell features a cone style junction. The skirted cone geometry of the reference forms the liquid junction with the test solution at the tip of the junction cone, producing a highly stable reference potential and consistent flow rates of electrolyte into the solution. A simple press of the top portion of the ISE makes it easy to empty the electrolyte fill solution and replace when necessary.

For the HI-4014 to measure potassium accurately, it is important that the ionic strength of the standards and sample be adjusted to a high and constant value with the potassium ionic strength adjuster (ISA) solution. The ISA ensures that the activity coefficient is constant so the concentration of free potassium ions can be measured. Measuring all solutions with a constant ionic strength reduces the margin of error between measurements. The HI-4014 potassium liquid membrane ISE can measure from 1µM (0.039 mg/L) to 1M (39,100 mg/L).