HORIBA ORP standard powders for verifying the response of an ORP (redox potential) electrode. Each sachet is made up with a known pH buffer immediately before use to produce a solution of defined millivolt value, giving you a reference point to confirm the electrode is reading correctly.

ORP electrodes are not calibrated in the way pH electrodes are — most meters display raw millivolts with no user calibration step. Instead you verify: measure a known standard, and if the reading falls outside the expected window the platinum or gold surface needs cleaning, or the reference junction is fouled or depleted. Without a standard there is no way to distinguish a genuinely unusual sample from a failing electrode.

Two values

• 160-51 (part no. 3200043618) — nominal 89 mV standard powder.
• 160-22 (part no. 3200043617) — nominal 258 mV standard powder.

Using both gives you two points across the range and will reveal a sluggish or drifting electrode that a single check might miss.

Why powder rather than a ready-made solution

Redox standards are inherently unstable in solution — they exchange with atmospheric oxygen and their potential shifts. Supplying the reagent as a dry powder means the standard is made fresh at the moment of use, so the millivolt value you compare against is trustworthy. Powders also store indefinitely, which suits laboratories that verify ORP only occasionally.

Applications

• Routine verification of ORP electrodes on LAQUA handheld and benchtop meters
• Confirming U-50 series sonde ORP response before a sampling event
• Diagnosing suspect redox readings in groundwater and landfill leachate monitoring
• Disinfection and chlorination control checks in drinking water and pool systems
• Wastewater treatment redox monitoring, including nitrification and denitrification stages
• Documented instrument verification under a laboratory quality system

Related items

ORP electrodes, replacement U-50 ORP sensors, electrode cleaning reagents and reference electrode filling solutions are all stocked — see the Horiba Parts & Accessories collection. A ready-made 255 mV ORP standard in 14 mL sachets for LAQUAtwin pocket meters is listed with the LAQUAtwin solutions.

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