ASTM G 220 : 2020

1.1This practice provides the steps necessary to prepare revisions to standards that specify the saturated calomel reference electrode (SCE) for measuring or controlling electrode potentials.

1.2The SCE contains mercury and, as a result, it may not be available in locations where mercury has been banned. This practice covers the selection and use of an alternative reference electrode.

1.3In test methods where the SCE is specified, it will be necessary to develop a new precision statement using the alternative reference electrode.

1.4This practice will not apply to electrometric pH determinations where the SCE has been used. (Electrometric pH measurement is an analytical method that is covered elsewhere.)

1.5The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6Warning—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.

1.7This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.8This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.