Metrohm 781 pH/Ion Meter - Manual (Page 90)

6.6 Standard and sample addition (781 only: Conc mode)
80
780/781 pH/Ion Meter, Manual
6.6 Standard and sample addition (781 only: Conc
mode)
In the ion measurement Conc mode a differentiation is made between
direct measurement and the standard or sample addition and subtrac-
tion methods.
All the method parameters for direct concentration determination are
described in Section 6.5. The descriptions of the ion parameters ,
measuring parameters and calculation parameters given there
also apply to the standard addition and sample addition types of ion
measurement. This is why this section contains only the method pa-
rameters which apply only to these types of measurement.
PARAMETER Conc
├
meas.type
:
meas.type: direct, std.add, smpl.add
The measurement type describes the analytical principle of ion meas-
urement. Select ' std.add ' if the analysis is to be carried out accord-
ing to the standard addition method, i.e. by the addition of defined
standard solutions to the sample. For the sample addition method, the
multiple addition of the sample solution to a standard solution, select
' smpl.add '.
Please note that changing this Conc parameter meas.type does not in-
clude a change of the current method. Within the mode Conc a method
contains all parameter settings.
6.6.1 Standard / Sample addition
PARAMETER Conc
:
├
standard addition / sample addition
: ├
type
├
conc.std.
├
report
└
addition
┬
manual
┬
no.of additions
│ ├
increment 1...n
│ └
stop V
├
auto dos
┬
dos.rate
│ ├
no.of additions
│ ├
V Exchange Unit
│ ├
increment 1...n
│ └
stop V
└
auto
┬
delta U
├
dos.rate
├
no.of additions
├
V Exchange Unit
└
stop V
The exact technique of standard and sample addition in the Conc
mode is described by the parameters selected under standard addi-
tion and sample addition :