Thermo Scientific NanoDrop One User Manual page 208

9 Learning Center
Prepare Samples and Blanks
Problems associated with blanking
• Residual sample was left on pedestal or in
cuvette before blank measurement was
performed. (Resulting sample spectra may
exhibit negative absorbance values,
indicating blank had more absorbance than
sample in that region of spectrum.)
• Blank measurement exhibits higher
absorbance than unknown sample at
analysis wavelength. (If buffer used as blank
differs in composition from that used to
resuspend sample, measurement results will
be incorrect.)
• Sample was inadvertently used to blank
instrument. (Resulting sample spectra may
exhibit negative absorbance values or, in
some cases, resemble a mirror image of a
typical pure nucleic acid or protein spectrum
as in example at right.)
Solutions for blanking problems
• Thoroughly clean and/or
pedestals and then:
– rerun blanking cycle, or
– measure new blank using new aliquot of
appropriate buffer solution, then measure
new aliquot of unknown sample
• For most applications, blank with the same
buffer solution used to resuspend the analyte
of interest. The blanking solution should be a
similar pH and ionic strength as the analyte
solution. For details, see "To measure
samples" in the application used.
206 NanoDrop One User Guide
Protein sample solution used to blank instrument results
in "mirror image" spectrum
recondition both
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