Abstract

This test method covers the apparatus and procedure for the electrometric measurement of oxidation-reduction potential (ORP) in water. The test method described has been designed for the routine and process measurement of oxidation-reduction potential. ORP is defined as the electromotive force between a noble metal electrode and a reference electrode when immersed in a solution. The ORP electrodes are inert and measure the ratio of the activities of the oxidized to the reduced species present. In addition, the ORP electrodes reliably measure ORP in nearly all aqueous solutions and in general are not subject to solution interference from color, turbidity, colloidal matter, and suspended matter. The apparatus to be used in the measurement of ORP includes: pH meter, reference electrode, oxidation-reduction electrode and electrode assembly. Materials necessary in the procedure for ORP measurement include chemical reagents, aqua regia, water, buffer standard salts, phthalate reference buffer solution, phosphate reference buffer solution, chromic acid cleaning solution, detergent, nitric acid, redox standard solution or ferrous-ferric reference solution, and redox reference quinhydrone solutions.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

1. Scope

1.1 This test method covers the apparatus and procedure for the electrometric measurement of oxidation-reduction potential (ORP) in water. It does not deal with the manner in which the solutions are prepared, the theoretical interpretation of the oxidation-reduction potential, or the establishment of a standard oxidation-reduction potential for any given system. The test method described has been designed for the routine and process measurement of oxidation-reduction potential.

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

1.3 This 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 and health practices and determine the applicability of regulatory limitations prior to use.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D1129 Terminology Relating to Water

D1193 Specification for Reagent Water

D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water

D3370 Practices for Sampling Water from Closed Conduits

Keywords

electrodes; ferrous-ferric reference solutions; iodide/triiodide; noble metal electrodes; ORP; oxidation-reduction potential; quinhydrone; redox; redox standards; reference electrodes; reference solutions; Electrical measurements; Electrodes; Ferrous-ferric reference solutions; Noble metal electrodes; ORP electrodes; Oxidation-reduction potential (ORP); Quinhydrone; Redox standards; Reference electrode; Wastewater testing/treatment; Water analysis;

ICS Code

ICS Number Code 13.060.60 (Examination of water for physical properties)

DOI: 10.1520/D1498-08

ASTM International is a member of CrossRef.

ASTM D1498