4
Learning Center
Prepare Samples and Blanks
68
NanoDrop One
C
with NanoDropQC Software User Guide
Thermo Scientific
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.)
Protein sample solution used to blank
instrument results in “mirror image” spectrum
Solutions for blanking problems
• Thoroughly
and/or
–
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.
