Metrohm 746 VA Trace Analyzer - Manual (Page 560)

7.7 Standard operating procedure in the context of GLP/ISO 9001 guidelines
746 VA Trace Analyzer / 747 VA Stand
7-61
7.7.4 Performing the determination
To perform the lead determination in the prepared sample solution, the following
steps are necessary:
1 Switch to dialog page ”MONITORING”
• Press the yellow <MONITORING> key.
2 Switching the program run mode to determination
If the paramete r Run mode is set to calibration , proceed as follows
• Use the cursor keys to select the field Run mode .
• Press the <CLEAR> key.
• Press the softkey <determ.> and confirm this entry with the <ENTER>
key.
3 Entry of the sample volume
Enter the sample volume as follows:
• Use the cursor keys to select the first field below the title Sample size/S0 .
• Press the <CLEAR> key.
• Enter 0.1 mL and confirm this entry with the <ENTER> key.
4 Start the determination
• Press the red <START> key.
• The sample solution is measured three times. On completion of the third
measurement, the program is interrupted. The screen shows the prompt
to add 50 µ L of the standard addition solution PbStd to the measuring
vessel ADD PbStd 50.000 uL > M .
5 First standard addition
• Remove stopper 25 25 and add 50 µ L of the lead ion standard solution to
the measuring vessel through the pipetting opening using a pipette. Then
close the pipetting opening with stopper 25 25 and press the <ENTER>
key.
• The spiked sample solution is measured three times. On completion of
the third measurement, the program is interrupted. The screen again
shows the prompt to add 50 µ L of standard addition solution PbStd to
the measuring vessel ADD PbStd 50.000 uL > M .
6 Second standard addition
• Remove stopper 25 25 and add 50 µ L of the lead ion standard solution to
the measuring vessel through the pipetting opening using a pipette. Then
close the pipetting opening with stopper 25 25 and press the <ENTER>
key.
• The sample solution spiked a second time is measured three times. On
completion of the third measurement, the results are calculated and the
reports and curves printed out (see section 4.2).