Genuine HORIBA conductivity standard solutions for calibrating HORIBA conductivity, TDS and salinity meters and cells — LAQUAtwin EC pocket meters, LAQUA 200 and WQ-300 handhelds, LAQUA 1500/2000 and F-70 benchtops, and the U-50 series field sondes.

Conductivity cells drift as the electrode surface fouls or platinizes, and the cell constant shifts with it. Calibrating against a certified standard restores the true cell constant. The critical point is to calibrate near the conductivity you actually measure — a cell calibrated at 84 µS/cm will not give reliable readings in seawater, and one calibrated at 111.8 mS/cm will be poor in drinking water.

Choosing the right standard

• 84 µS/cm — deionized, distilled and low-conductivity water; boiler feedwater and condensate
• 1,413 µS/cm (1.41 mS/cm) — the general-purpose standard. Drinking water, groundwater, surface water and most environmental samples
• 12.88 mS/cm — brackish water, wastewater, nutrient and hydroponic solutions, higher-TDS process water
• 111.8 mS/cm — seawater, brines, salinity work and high-conductivity industrial streams

Where a wide range is measured, calibrate at multiple points. The four-bottle 103-S set covers all four values and is the usual choice for a multi-point calibration or for equipping a new instrument.

Handling for reliable results

• Pour into a clean beaker and discard after use — never return used standard to the bottle
• Conductivity is strongly temperature dependent; allow the standard to reach the same temperature as your samples before calibrating
• Keep bottles tightly capped; evaporation concentrates the solution and raises its true value
• Rinse the cell thoroughly with deionized water between standards, and again before measuring
• Work from low conductivity to high to minimize carry-over

Related items

Conductivity electrodes and cells in K=0.1, K=1 and K=10 cell constants, pH buffers, ORP standards and electrode cleaning reagents are all stocked — see the Horiba Parts & Accessories collection. The 60 mL conductivity calibration set that fits the LAQUA 200 and WQ-300 carrying cases is listed with the WQ-300 sensor accessories.

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