Metrohm MVA-21 - Manual (Page 11)

Application Bulletin 403/1 e
Installation instruction for MVA-21
5.2. Brightener determination series
5.2.1. Manual operation
•
Dosing Unit «894/D1 50mL VMS» connected to Dosino
1 has to be prepared with VMS.
•
Dosing Unit «894/D2 2mL Brightener» connected to
Dosino 2 has to be prepared with brightener
concentrate.
•
Dosing Unit «894/D3 2mL Suppressor» connected to
Dosino 3 has to be prepared with suppressor
concentrate.
•
Plating bath samples are placed on position 1 to 28 of
the sample rack using the sample vials for 50 mL
(6.2747.010). ). The exact sample volume needed for
the determination has to be pipetted into the vial.
•
Rinsing solutions are placed on position 29 to 56 of the
sample rack using the sample vials for 50 mL
(6.2747.010). Usually the same volume of distilled
water is used for rinsing like it was used for the sample.
The rinsing solution has to be placed on the inner circle
on the neighboring position of the sample (Sample
position + 28).
Fig 15: Example positions of solutions on the sample rack
6.2041.450
5.2.2. Workplace
•
In the «Run» window on the tab «Determination series»
create a sample table
Fig 16: Example sample table
•
As sample type S AMPLE has to be selected.
•
For «Sample amount» the volume pipetted into the vial
has to be entered.
5.2.3. Course of events
•
The execution the determination by modified linear
approximation technique is controlled by the 894
Professional CVS and viva.
a) The measuring vessel is emptied using the 843
Pump Station.
b) The intercept solution is automatically prepared at
the beginning of each determination, by dosing
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
build-in peristaltic pump of the 858 Professional
Sample Processor. 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).
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