HORIBA combination ion-selective electrodes measure a specific ion directly in solution, in millivolts converted to concentration against a two-point calibration. Each one ships as a complete working kit rather than a bare electrode, so you can calibrate and measure the day it arrives.

What is in every kit

• Combination ion-selective electrode (sensing element and reference in one body)
• 100 ppm and 1000 ppm standard solutions, 50 mL each
• Electrode filling solution, 50 mL
• Ionic strength adjustor (ISA), 50 mL
• Syringe and droppers
• Instruction manual

The ammonia, calcium, chloride and potassium kits also include spare sensing parts: 3 membrane caps with the ammonia electrode, and 2 electrode tips each with the calcium, chloride and potassium electrodes.

Available ions

• 5002S-10C (3200698386) — ammonia (NH₃)
• 6583S-10C (3200697410) — calcium (Ca²⁺)
• 6560S-10C (3200697407) — chloride (Cl^-)
• 6561S-10C (3200693774) — fluoride (F^-)
• 6581S-10C (3200697408) — nitrate (NO₃^-)
• 6582S-10C (3200697409) — potassium (K⁺)

Why the ionic strength adjustor matters

An ion-selective electrode responds to ion activity, not concentration, and activity depends on the total ionic strength of the solution. Adding the same volume of ISA to both your standards and your samples forces them to a common, high ionic strength, so activity tracks concentration and the calibration transfers correctly to the sample. Skipping the ISA is the most common reason ISE results come back wrong. For fluoride the ISA also complexes interfering aluminum and iron and buffers the pH.

Applications

• Ammonia in wastewater influent and effluent, and nitrification monitoring
• Nitrate in drinking water, groundwater, surface water and soil extracts
• Fluoride in drinking water fluoridation control and industrial effluent
• Chloride in water, brines, food products and concrete or aggregate extracts
• Calcium in water hardness, agriculture and food and beverage analysis
• Potassium in soil and plant tissue extracts, fertilizers and nutrient solutions
• Teaching laboratories demonstrating potentiometric ion measurement

Documentation

• HORIBA water quality document library — electrode brochures and manuals

Consumables

Replacement ion cartridges, ammonia membrane caps, standard solutions and ionic strength adjustors are stocked separately — see the Horiba Parts & Accessories collection. Treat the sensing cartridge or membrane as a consumable and budget for periodic replacement.

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