Thermo Scientific NanoDrop One, User Manual

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18
Learning Center
Prepare Samples and Blanks
200 NanoDrop One User Guide Thermo Scientific
For best results:
• 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.
• Measure new blank before each set of samples. It is not
necessary to blank the instrument before each sample
measurement unless the samples are dissolved in different
buffer solutions.
• Measure a new blank every 30 minutes.
• Run a blanking cycle to assess the suitability of your
blanking solution before using it to perform sample
measurements. For a quick demonstration, watch the
multimedia training
Evaluating a Blanking Solution for
Suitability .
The resulting spectrum should vary no more than 0.04 A
(10 mm equivalent) across the spectrum, especially at the
analysis wavelength as in the example at the right.
If the resulting spectrum is greater than 0.04 A around the
analysis wavelength, that buffer solution may interfere with
the sample analyses, especially for low concentration
samples. See below for details.
Good blanking buffer (measured abs < 0.04)
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