Owner manual
4.3 Lead determination with calibration curve
746 VA Trace Analyzer / 747 VA Stand
4-35
6
Addition of acetate buffer
• Use a pipette to add 1 mL acetate buffer (1 mol/L, pH 4.6) to the
measuring vessel through the pipetting opening. Then close the pipet-
ting opening using stopper 2525 and press the <ENTER> key.
7
Measurement of the 1
st
calibration solution
• Measurement of the 1
st
calibration runs as follows (see also section
4.3.3):
− Purging and stirring for 180 s.
− Call-up of the segment DPASV for measured value recording. The
lead present in the solution is enriched at the hanging mercury
drop with stirring at a measurement voltage of –600 mV and then
determined anodically without stirring from –600 … –200 mV. The
selected measurement mode DP leads to a current peak whose
maximum lies at ca. –400 mV.
− The DPASV segment is then repeated twice. The three single
measurements are allocated the VR numbers 00, 01 and 02.
• After the 3
rd
measurement, the program is interrupted. The screen shows
the prompt to change the measuring vessel:
8
Empty the measuring vessel
• Empty the measuring vessel, rinse it thoroughly with dist. water and
replace it in the 747 VA Stand.
The measuring vessel contains mercury, which must be disposed of in
the proper manner (see section 7.2.3).
9
Measurement of the 2
nd
calibration solution
• Repeat steps 5 … 8 with 10 mL of calibration solution Pb-2 with a
mass concentration of 5 µµg/L. You obtain three single measurements
with the VR numbers 10, 11 and 12.
10
Measurement of the 3
rd
calibration solution
• Repeat steps 5 … 8 with 10 mL of calibration solution Pb-3 with a
mass concentration of 10 µµg/L. You obtain three single measurements
with the VR numbers 20, 21 and 22.
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DOS Acetate 1.000 mL > M
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Change measuring vessel
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