Section 7- UV-VIS
7. UV-VIS
The ‘UV/VIS Absorbance’ module allows the NanoDrop
®
ND-1000 Spectrophotometer to function as a conventional spectrophotometer.
Sample absorbance is displayed on the screen from 220 nm to 750 nm and cursors permit the measurement of individual peaks.
Sample Volume Requirements
Field experience has indicated that 1 ul samples are sufficient to ensure accurate and reproducible results when measuring most
aqueous samples. If you are unsure about your sample composition or your pipettor accuracy, a 1.5-2 ul sample is recommended to
ensure that the liquid sample column is formed and the light path completely is covered by sample.
Measurement Concentration Range
All ND-1000 spectrophotometers will measure absorbance up to the 10mm pathlength equivalent of 15 A. ND-1000s with serial
numbers >500 or those that have been field retrofitted, can utilize the short path length (0.2mm) which enables the 10mm pathlength
equivalent of 75 A.
Unique Screen Features
λ
1/Abs1
and
λ
2/Abs2:
current values of the user-selectable wavelength cursors and corresponding absorbencies for a 1 mm
pathlength. The wavelengths can be set by dragging the cursor, using the up/down arrows or typing in the desired wavelength.
Baseline:
the absorbance of the user selectable-baseline (horizontal) cursor. The user may drag this cursor to a new vertical position
to create a new baseline. The absorbance value of the baseline is subtracted from the absorbance of the spectrum.
Max Absorbance:
used to rescale the upper limit of the vertical axis.
Hi Abs:
samples with high absorbance (up to 75 A equivalent @ 10 mm path) can be measured directly (applicable for instruments with
serial numbers >500 only or that have been field-retrofitted). This capability is selected by choosing the ‘Hi Abs’ button on the header
bar. When this is selected, the absorbance is measured using the short path (0.2mm) and plotted as a red line normalized to a 0.1mm
path for easier visual comparison as shown above. Sample ID label will be stored with sample data in the file folder
“C:\NanoDrop
Data\User name\ HiAbs”.
This data cannot be imported into the Data Viewer but can be opened with Excel type spreadsheets.
Normalize: This is a user-selectable feature in this module
.
If selected, the software will automatically normalize the spectrum
based on the lowest absorbance value in the range 400-700 nm.
Show Report:
formatted for 200 samples although the buffer size can be increased to accommodate thousands of samples.
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