Ionode IJ pH V5.1 Bedienungsanleitung PDF herunterladen (Seite 10)

Ionode IJ Instruction Manual 10

The reference half-cell completes the circuit.

The primary IJ reference is a silver/silver

chloride element in a gelled saturated

potassium chloride electrolyte. This makes

solution contact with the secondary sleeve

electrolyte through a low porosity wick. Usually,

the sleeve electrolyte is concentrated

potassium chloride. However, as the IJ

reference has a double junction, it allows the

use of other suitable sleeve electrolytes.

Potassium chloride is the most commonly used

reference electrolyte because of the similar size

and mobility of the potassium and chloride ions.

This minimizes charge separation when the

sleeve electrolyte diffuses into the sample

Solution contact between the sleeve electrolyte

and the sample is through the porous junction

between the ground stem and the sleeve. This

constriction allows uninhibited movement of

ions between the sample and reference half cell

to assure a repeatable reference junction

potential. At the same time it does not grossly

contaminate the sample with reference ions.

In common electrode designs, a porous

restriction (typically a porous ceramic or fibre

wick) is used to slow the flow (see Figure 10a).

K

+

Cl

-

(a)

Cl

-

Cl

-

Cl

-

Cl

-

K

+

K

+

K

+

K

+

(b)

Figure 10

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 43 44

Kommentare zu diesen Handbüchern

Keine Kommentare