Which electrodes can still be used for titration?

8/31/2023 | Stefan Kaus

In addition to aqueous and non-aqueous pH titrations, there are many other titration applications where silver, platinum, double platinum and ion-selective electrodes are used, as well as a photometric sensor for all color change titrations.

What criteria do I now use to select the right electrode for my titration application?

The first and most important criterion is the type of titration application. As a rule, this results from the method description and the titrant used.

Example 1: If the titrant is silver nitrate, the application is a precipitation titration using a silver electrode with normal Ag/AgCl reference system AgCl 62 (see Fig. 1) or a silver electrode with a glass electrode as "reference electrode" AgCl 62 RG. RG means “Reference Glass”. In this case, there is no opening for refilling the electrolyte. See Fig. 2 AgCl 62:

Example 2: If the titrant is sodium thiosulfate, then it is a redox titration in which a platinum combination electrode such as the Pt 62 or Pt 61 is used. See Fig. 3 Pt 61:

As with the silver combination electrode, there are also low-maintenance platinum combination electrodes with a glass electrode as the reference system. These RG electrodes can then always be used if the pH value does not change during the titration.

Digital IDS versions of the silver and platinum combination electrodes are also available, such as the
Ag 62 IDS and Pt 62 RG ID

For applications with polarizable electrodes such as SO₂ titration in wine, determination of the bromine number and Karl Fischer ("KF") titration, there are double platinum electrodes such as the Pt 1200 and the KF 1100. See Fig. 4 KF 1100:

An overview of the applications and the corresponding electrodes can be found in Table Applications.

Table applications - recommended electrodes

	Application	Details	Type of electrode	Order number
Precipitation titrations	Titrations with silver nitrate - also back titrations with ammonium thiocyanate, sodium or potassium chloride etc. .	General chloride, chloride/NaCl ("salt") in foodstuffs	AgCl 62	285102413
			AgCl 62 RG	285102100
			Ag 62 IDS	285102150
		Cyanide, bromide, iodide	Ag 6280	285102343
			Ag 62 RG	285102090
			Ag 62 IDS	285102150
		Mercaptans and hydrogen sulfide, cyanide	AgS 62 RG	285102110
			Ag 1100 + A 1180	285103607 + 1057997
	Titrations with lanthanum nitrate	Fluoride	F 1100 PLH + reference electrode	285216295
	Titrations with Hyamine,	Anionic, cationic and non-ionic surfactants	TEN 1100 + reference electrode	285096980
	Cetylpyridinium chloride
	Sodium dodecyl sulfate
	Sodium tetraphenylborate
Redox titrations	Titrations with iodine and sodium thiosulfate (iodometry), potassium permanganate, cerium(IV) sulfate, potassium dichromate, ferrous (II) sulfate	Iodine value, peroxide value, chlorine, hypochlorite, potassium permanganate, etc.	Pt 62	285102019
		Oxidizability, H2O2, oxygen according to Winkler	Pt 61	285102002
		Nitrate	Pt 62 RG	285102070
			Pt 62 RG IDS	285102140
	Titrations with ammonium iron(II) sulfate	COD	Pt 61	285102002
		COD with sample changer	Pt 5901	285105065
	Titrations with iodine and polarizable electrode (dead stop)	SO2, Bromine number, etc.	Pt 1200	285103512
	Volumetric KF-titration		KF 1100	285102030
	Coulometrische KF-Titration	(Indicator electrode only)	KF 1150	285102060

Except for the KF 1100 and KF 1150, all electrodes have a plug head. A suitable coaxial electrode cable such as the L 1 A or L 2 A (Fig. 5 Koaxialkabel L 1 A/L 2 A) is also required.

OptiLine 6, one sensor for all titrations on color change

For all titrations that are (have to be) performed on color change, you can use the OptiLine 6 digital photometric sensor (see Fig. 6 Optiline 6). The OptiLine 6 is connected via USB to the TL 7XXX titrators, whereby the wavelength used during the titration (= 6, 470 - 625 nm) is defined within the titration method. Due to the additional BNC and DIN connector, the OptiLine 6 can also be connected to older titrators, as well as to the TitroLine® 5000. The wavelength and other settings can then be preset via PC software.