Standard Practice for Replacing Saturated Calomel Reference Electrode (SCE) for Measuring Electrode Potentials

Importancia y uso:

5.1 Electrode potential measurement is an essential step in many electrochemical corrosion test methods and practices.

5.2 The SCE has been widely specified for laboratory tests because it is reliable, accurate, simple to use, and it has been readily available. However, because this device contains mercury, and mercury has recently been banned by some governmental agencies, it may not be available in locations where mercury is banned. As a result, test methods using the SCE may not be possible in locations where mercury is banned. Therefore, it is necessary to establish an alternative reference electrode for these standards.

5.3 The KCl saturated, silver/silver chloride reference electrode, Ag/AgCl (sat KCl), is a satisfactory replacement for the SCE in laboratory test methods and practices. This reference electrode should provide comparable performance and accuracy to the SCE.

5.4 It will be necessary to carry out interlaboratory test programs for each test method where the Ag/AgCl (sat KCl) electrode is specified to replace the SCE, in order to develop the precision of the method using the new reference electrode.

Note 1: In cases where a test method specifies that either the SCE or the Ag/AgCl (sat KCl) reference electrode may be used, and the ILS program used to develop the precision of the method included significant numbers of participants using each of these reference electrodes, no additional testing is required.

Subcomité:

G01.11

Volúmen:

03.02

Número ICS:

25.220.99 (Other treatments and coatings), 71.040.50 (Physicochemical methods of analysis), 77.060 (Corrosion of metals)

Palabras clave:

Ag/AgCl (sat KCl); calomel electrode; liquid junction; mercurous ion; reference electrode; saturated calomel electrode; SCE; silver chloride; silver/silver chloride electrode;