Bio-Rad SmartSpec Plus Spectrophotometer - Manual (Page 47)

7.3 Spectral Scanning
SmartSpec Plus can collect data over a range of wavelengths and then plot those
absorbances. There are both Fast and Slow scans: the fast scan generally takes a minute
or less to accomplish while the slow will take several minutes, but results in more accurate
absorbance data and a smoother curve. The scanning time is dependent on the range
scanned and the absorbance of the sample. You can improve the accuracy of fast scans
by specifying more than one repetition of the scan. The scan can be repeated as many as
five times and the readings are averaged before plotting; five fast scans can be carried
out more rapidly than one slow scan.
SmartSpec Plus will identify the local maximum and minimum over the scanned region,
or you can specify as many as four different subregions within the scanned area, and
SmartSpec Plus will identify the maximum and minimum in each subregion. This is
available through the Options menu.
SmartSpec Plus can smooth the curve by taking a running average of absorbance readings
at 5 consecutive wavelengths. For example, it will average the absorbance readings at
255, 256, 257, 258, and 259 nm and plot this average at 257. Then it will average the
absorbance readings at 256, 257, 258, 259, and 260 and plot this average at 258 nm.
This is available through the Options menu.
When you press Scan, SmartSpec Plus will prompt for upper and lower limits of the scan.
• Use the number keys to input the starting wavelength and press Enter. Then use
the number keys to input the ending wavelength and press Enter. You can move
inside the number fields with the right and left arrow keys.
• If you do not want to subtract a background reading, press Enter and SmartSpec
Plus is ready to begin the scan. If you do want to subtract a background, press
Select to toggle from No to Yes and press Enter.
• Use the number keys to input the background wavelength and press Enter.
SmartSpec Plus next lets you choose between the Fast and Slow scans.
• If you prefer the slow scan, press Select to toggle from Fast to Slow and press Enter.
Press Enter to accept a Fast scan.
If you choose the Fast scan, then you can specify the number of repetitions.
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Enter the number of
successive scans (1–5):
Begin scanning at ____ nm
End scanning at ____ nm
Do you want to subtract
a background reading? No
Enter wavelength for
background: _____ nm
Select type of scan: Fast