Agilent Technologies All Troubleshooting Guide download pdf (Page 49)

Lab Exercise: Qualitative Data Analysis

Isoabsorbance Plot

selected in Data Analysis, that of the peak at 4.85 minutes. Convince yourself

that this is the case by moving the vertical cursor to a time of 4.85 minutes.

6) Now point the cursor at the horizontal line across your Isoabsorbance plot. As

you move this cursor up and down, watch the chromatogram in the lower

section of the screen. The black chromatogram changes as you change the

sample signal wavelength.

7) Change the cursor mode to Signal. To extract a signal corresponding to the

sample and reference wavelengths you determined earlier, you can simply

type the values you want in the box at the upper left. To access the reference

signal click in the check box next to Ref.

8) You can also select the sample and reference signals graphically. Press and

hold the CNTRL key while you move the sample signal band or the reference

signal band. You can keep the same bandwidth, but just adjust the position of

the band, by releasing the CNTRL key and then moving the signal band.

Note: If you want to start over, just exit the Isoabsorbance plot and redraw it

by selecting the Spectra menu, then Isoabsorbance plot. Don’t forget to

change the cursor mode to Signal.

9) When you are satisfied with your extracted signal, select the Copy button at

the lower left corner of the Isoabsorbance plot. Minimize the isoplot window

and view the extracted signal. Overlay the extracted signal with signal B.

You will have to select All Loaded Signals with the drop box.

Did you improve the signal to noise ratio of the peak?

10) You may continue to try other sample signals, bandwidths and references.

When you have finished, record the optimized values here.

Sample Signal__________

Sample Signal Bandwidth__________

Reference Signal__________

Reference Bandwidth__________

11) Close the IsoPlot.

If you have time, optimize the Diode Array signals for the 3rd and last major

peak in the acquisition data file. Record the results here and use in the next

laboratories.

Sample Signal__________

Sample Signal Bandwidth__________

Reference Signal__________

Reference Bandwidth__________

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Agilent Technologies All Troubleshooting Guide Page 49