USGS Method NFM-643C

The instrument system that is used to measure pH must be tested before each field trip, and it must be cleaned soon after use. Because of the variety of pH meters and electrodes available, read thoroughly the instruction manual provided by the manufacturer. Every pH instrument must have a log book in which its manufacturer make and model, serial or property number, and all repairs and calibrations are recorded.

pH electrodes and meters are sophisticated electronic instruments that require care in handling and operation. Buffers and instruments for pH measurement (including multiparameter instruments) must be protected from dirt and fouling, and extreme heat or freezing conditions, either while in the field or in storage. Protect instruments from jostling or sudden impacts.

Keep instrument systems clean and dry when they are not in use. Some of the equipment or procedures described within NFM 6.4 or other NFM1 chapters may not be applicable if different or newer instruments will be used. Always check the manufacturer’s instructions in addition to adhering to USGS protocols for quality control and assurance.