Metrohm 746 VA Trace Analyzer - Manual (Page 133)

4 Introduction to the operation
746 VA Trace Analyzer / 747 VA Stand
4-48
• Shortly after the start of the determination, the prompt to add 10 mL of
calibration solution Pb-1 to the measuring vessel appears on the
screen:
5 Addition of 1 st calibration solution
• Remove stopper 25 25 and use a pipette to add 10 mL of calibration
solution Pb-1 with a mass concentration of 2.5 µµg/L to the measuring
vessel through the pipetting opening. Press the key.
• The screen shows the prompt to add 1 mL acetate buffer to the measur-
ing vessel:
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 25 25 and press the key.
• The screen shows the prompt to add 100 µ L of the solution CdRefSol
with the internal standard to the measuring vessel:
7 Addition of the internal standard
• Use a pipette to add 100 µµL of the cadmium standard solution with a
mass concentration of 1 mg/L to the measuring vessel through the pi-
petting opening. Then close the pipetting opening using stopper 25 25 and
press the key.
8 Measurement of the 1 st calibration solution
• Measurement of the 1 st calibration runs as follows (see also section
4.4.3):
− Purging and stirring for 180 s.
− Call-up of the segment DPASV for measured value recording.
Lead and cadmium are enriched with stirring at the hanging mer-
cury drop at a measurement voltage of –800 mV and then deter-
mined anodically without stirring from –800 ... –200 mV. The se-
lected measurement mode DP leads to a current peak for lead
whose maximum lies at ca. –400 mV and a current peak for cad-
mium with a maximum at ca. –580 mV.
− The DPASV segment is then repeated twice. Both the three single
measurements for the substance lead and also the three single
Ъ ЪДДД ДДД MEAS.TASK MESSAGE ДДДДДДДДДДДДДДДДДД ДДДДДДДДДДДДДДДДДД¿ ¿
³ ³
³ ³
³ ³
CSOLN Pb-1 10.000 mL > M
³ ³
³ ³
³ ³
А АДДД ДДД : continue ДДДДДДДДДДДДДДДДДД ДДДДДДДДДДДДДДДДДДЩ Щ
Ъ ЪДДД ДДД MEAS.TASK MESSAGE ДДДДДДДДДДДДДДДДДД ДДДДДДДДДДДДДДДДДД¿ ¿
³ ³
³ ³
³ ³
DOS Acetate 1.000 mL > M
press to break
³ ³
³ ³
³ ³
А АДДД ДДД : continue ДДДДДДДДДДДДДДДДДД ДДДДДДДДДДДДДДДДДДЩ Щ
Ъ ЪДДД ДДД MEAS.TASK MESSAGE ДДДДДДДДДДДДДДДДДД ДДДДДДДДДДДДДДДДДД¿ ¿
³ ³
³ ³
³ ³
ADD CdRefSol 100.000 uL > M
press to break
³ ³
³ ³
³ ³
А АДДД ДДД : continue ДДДДДДДДДДДДДДДДДД ДДДДДДДДДДДДДДДДДДЩ Щ