Metrohm MVA-20 - Manual (Page 12)

Application Bulletin 402/1 e
Installation instruction for MVA-20
VMS from Dosino 1 and suppressor concentrate
from Dosino 3.
c) After the determination of the intercept value, the
plating bath sample is transferred from the sample
rack to the measuring vessel by means of the built-
in peristaltic pump of the 919 IC Autosampler plus.
The sample is added on top of the intercept
solution.
d) Standard addition is carried out automatically with
brightener concentrate from Dosino 2.
e) At the end of each determination the measuring
vessel is emptied using the 843 Pump Station.
f) The transfer tubing from the sample changer to the
measuring vessel is rinsed with the rinsing solution
placed on the rack of the sample changer.
g) After the transfer tubing is rinsed the measuring
vessel is automatically emptied and rinsed using
the 843 Pump Station.
Next sample starts again from a).
6. Remarks
6.1. Single additive setup
If the system is only used for suppressor or brightener
determination the unused port at the T connector
(6.2744.290) has to be closed with a threaded stopper
(6.2744.060).
6.2. Combination of applications
The determination of suppressor by dilution titration (DT)
and the determination of brightener by modified linear
approximation technique (MLAT) can also be combined in
one series.
6.3. Storing dosing units
When the dosing units are not used (during the night, over
the weekend) the dosing cylinder has to be rinsed with
water. Otherwise elemental copper can be formed or
additives can precipitate between the valve disk and the
distributor disk or in the tubings. A blockage can damage
the 800 Dosino. Emptying the cylinder and filling it with
water is sufficient to prevent a blockage.
6.4. Storing electrodes
When the electrodes are not used (during the night, over the
weekend) the electrodes should be thoroughly rinsed.
Working and auxiliary electrode can either be stored in
deionized water or dry. The reference electrode should be
stored separately in a vial filled with deionized water (KCl
solution, in case KCl is used as bridge electrolyte), so that
the reference electrode immerses at least to the rim of the
electrolyte vessel.
6.5. Waste container
The waste container must not be closed completely. For
pressure balancing in the waste container, keep at least one
opening unsealed. Overpressure would lead to a
malfunction of the drain pump.
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