6. Apparatus
6.1 Manual Titration Apparatus :
6.1.1 Meter, a voltmeter or a potentiometer that will operate with an accuracy of 60.005 V and a sensitivity of 60.002 V over a range of at least 60.5 V when the meter is used with the electrodes specified in 6.1.2 and 6.1.3 and when the resistance between the electrodes falls within the range from 0.2 to 20 MΩ.
The meter shall be protected from stray electrostatic fields so that no permanent change in the meter readings over the
entire operating range is produced by touching, with a grounded lead, any part of the exposed surface of the glass
electrode, the glass electrode lead, the titration stand, or the meter.
NOTE 4—A suitable apparatus could consist of a continuous-reading
electronic voltmeter designed to operate on an input of less than 5 × 10 −
12 A, when an electrode system having 1000-MΩ resistance is connected
across the meter terminals and provided with a metal shield connected to
the ground, as well as a satisfactory terminal to connect the shielded
connection wire from the glass electrode to the meter without interference
from any external electrostatic field.
6.1.2 Sensing Electrode, Standard pH, suitable for nonaqueous
titrations.
6.1.3 Reference Electrode, Silver/Silver Chloride (Ag/
AgCl) Reference Electrode, filled with 1M–3M LiCl in ethanol.
6.1.3.1 Combination Electrodes—Sensing electrodes may
have the Ag/AgCl reference electrode built into the same
electrode body, which offers the convenience of working with
and maintaining only one electrode. The combination electrode
shall have a sleeve junction on the reference compartment and
shall use an inert ethanol electrolyte, for example, 1M–3M
LiCl in ethanol. These combination electrodes shall have the
same response or better response than a dual electrode system.
They shall have removable sleeves for easy rinsing and
addition of electrolyte.
NOTE 5—A third electrode, such as a platinum electrode, may be used
to increase the electrode stability in certain systems.