Genuine HORIBA pH buffer and standard solutions for calibrating any HORIBA pH meter or electrode — LAQUAtwin pocket meters, LAQUA 200 and WQ-300 handhelds, LAQUA 1500/2000 and F-70 benchtops, and the U-50 series field sondes.

A pH measurement is only as good as the buffer it was calibrated against. Buffers absorb carbon dioxide from the air and drift over time once opened, and alkaline buffers drift fastest — a pH 10 bottle left open on the bench will read low within weeks. Using fresh, in-date buffer is the single most effective way to keep pH data defensible.

Two buffer conventions — choose the right one

• USA / technical series — pH 4.01, 7.00 and 10.01. The convention used across most US laboratories and regulatory programs.
• NIST / DIN series — pH 4.01, 6.86 and 9.18. Used where NIST-traceable buffer values are specified.

Do not mix conventions within one calibration. If your SOP or permit names buffer values, match them exactly.

What is available

• Ready-to-use 500 mL bottles — pH 2, 4, 7, 9 and 10. The standard choice for routine bench and field calibration.
• Solution sets — three buffers plus KCl reference filling solution in one box, in USA or NIST values. The economical way to equip a new meter.
• Concentrated solution — pH 4 concentrate, diluted before use to reduce shipping and storage volume.
• Buffer powders — pH 4, 7 and 9 sachets made up with deionized water as needed. Powders do not drift in storage, so they are ideal for infrequent use, remote sites and long shelf-life stock.

Handling for reliable results

• Pour buffer into a clean beaker and discard it after use — never return used buffer to the bottle
• Keep bottles tightly capped and out of direct sunlight
• Rinse the electrode with deionized water between buffers, and blot rather than wipe
• Calibrate at the temperature of your samples wherever possible
• Replace alkaline buffers more frequently than acidic ones

Related items

Conductivity standards, ORP standards, ion standards, ionic strength adjustors, electrode filling solutions and electrode cleaning reagents are all stocked — see the Horiba Parts & Accessories collection. The 4 L pH 4 standard solution is listed with the U-50 Series accessories, and the 60 mL pH calibration set that fits the LAQUA 200 and WQ-300 carrying cases is listed with the WQ-300 sensor accessories.

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