7.2 Hardware problems
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46
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7.1.3
Quantification
The concentration of the analyte is determined by standard addition tech-
nique. The following section lists some requirements for a successful stan-
dard addition:
■
The concentration of the analyte in the standard solution must be
known. Standard stock solutions with a certified concentration are
commercially available for many metal ions.
■
Diluted metal standard solutions (mg/L range) should be acidified to pH
1 - 2, to avoid loss of analyte due to the formation of hydroxides.
■
Very diluted standard solutions (µg/L range) are not stable and should
be prepared freshly.
■
Volume and concentration of the standard addition solution should be
chosen in a way that the total volume of additions does not exceed
10 % of the total volume of the measuring solution. Normal addition
volumes are in the range 50 - 200 µL.
■
Volume and concentration of the standard addition solution should be
chosen in a way that the peak after the last addition is 2 - 5 times
higher than the sample peak.
■
The sample peak and all standard addition peaks have to be within the
linear working range of the method
7.2
Hardware problems
Problem
Cause
Remedy
Potentiostat - the
potentiostat cannot
be connected to the
software.
The USB cable is not con-
nected.
Connect the USB cable between potentiostat
and PC/laptop as described in
.
The potentiostat is
switched off.
Switch on the potentiostat and check for the
green status LED which indicates that the
power is on.
The connect button is
clicked too shortly after
switching on the instru-
ment.
After the potentiostat is switched on it takes a
few seconds before the USB communication is
established. Allow 5 s and retry to connect the
potentiostat.
Potentiostat - the
potentiostat cannot
be turned on or
switches off immedi-
ately.
Battery level too low.
Connect the potentiostat to the power grid
using the USB power supply unit
. Charge the battery for at least
1 hour before switching on the potentiostat
again.
Summary of Contents for 2.946.0010
Page 1: ...946 Portable VA Analyzer 2 946 00x0 Manual 8 946 8003EN ...
Page 2: ......
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Page 12: ...1 4 Symbols and conventions 4 Note This symbol marks additional information and tips ...
Page 79: ... 8 Technical specifications 71 8 8 Connection Connection USB version 1 1 or higher ...