HI4015 – Feststoffelektrode, Halbzelle

The HI4015 silver/sulfide selective electrode is a potentiometric half-cell sensor housed within an epoxy body. The internal elements are isolated from the sample by a compressed silver/silver sulfide sensing membrane. This solid-state sensor requires a separate reference electrode to complete the measurement system. Hanna's solid-state half-cell ISEs are designed for use with the HI5315 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. Measuring all solutions with a constant ionic strength reduces the margin of error between measurements. The HI4015 silver/sulfide solid-state ISE can measure silver from 1µM (0.11 mg/L) to 1M (107,900 mg/L) and sulfide from 0.1µM (0.003 mg/L) to 1M (32,100 mg/L). Silver (Ag+) For the HI4015 to measure silver accurately, it is important that the ionic strength of the standards and sample be adjusted to a high and constant value with the halide ionic strength adjuster (ISA) solution. The ISA ensures that the activity coefficient is constant so the concentration of free silver ions can be measured. Conversion Table for Ag+ Multiply moles/L (M) to ppm (mg/L) 1.0787 x 105 ppm (mg/L) to M (moles/L) 9.27 x 10-6 Sulfide (S2-) For accurate sulfide measurement, it is important that sulfur is released from hydrogen and that sulfide oxidation is prevented with the sulfide antioxidant buffer solution (SAOB). The SAOB ensures that the solution pH is above pH 12, reducing the effect of interfering ions and releasing sulfur from hydrogen ions. SAOB also acts to stabilize the activity coefficient so the concentration of free sulfide ions can be measured. Conversion Table for S2- Multiply moles/L (M) to ppm (mg/L) 3.207 x 104 ppm (mg/L) to M (moles/L) 3.12 x 10-5 Features at-a-glance Fixed Sensing Modules Solid-state half-cell ISEs are electrodes that detect free ions in a solution. The highly insoluble, compressed sensing pellet is attached to the HI4015 silver/sulfide half-cell by a fixed sensing module for ease of use. Durable Epoxy Body The probe body of the silver/sulfide half-cell ISE is composed of durable epoxy resin. BNC Connection The HI4015 has a universal BNC connector for easy connection to any benchtop meter with a female BNC probe input. Theory of Operation A solid-state sensor electrode develops a voltage due to the ion exchange that occurs between the solution and the inorganic membrane. An equilibrium occurs due to the highly limited solubility of the membrane material in the sample. When the ionic strength of the solution is fixed by the addition of ISA, the voltage is proportional to the concentration of free ions in solution organic ion exchange resin. When the ionic strength of the solution is fixed by the addition of ISA, the voltage is proportional to the concentration of free ions in solution.