User manual

Section 7- Diagnostics and Troubleshooting
If the warning persists and the user visually confirms that the liquid column is forming, perform a calibration check. If
the instrument is out of calibration, contact
Technical Support. Outside of the US and Canada, please contact your
local NanoDrop products distributor.
Small Volume Sample Measurement
This error occurs when the small sample volume feature available in the Nucleic Acid and Protein A280
applications has been selected for use with a sample a 10 mm equivalent absorbance of less than 3.0. De-select
the small volume option, and wipe away the aliquot. Use a larger sample volume aliquot and re-measure.
Sample Related Issues
Sample Carryover
Simple wiping of the upper and lower measurement pedestal with a dry laboratory wipe is highly effective in
eliminating carryover for samples differing in concentration by as much as three orders of magnitude.
Effect of Evaporation and Solvents
A fresh aliquot of sample should be used for each measurement. Evaporation of the sample during the
measurement cycle usually has a minimal effect on absorbance readings and may result in a 1-2% increase in
sample concentration. However, repeated measurements on the same sample aliquot will result in increasing
concentrations and or column breakage. Highly volatile solvents, such as hexane, will likely evaporate before the
measurement can be completed. Less volatile solvents such as DMSO can be used successfully.
The cuvette option (model 2000c only) may be useful for samples in volatile buffers or solvents.
Sample Homogeneity
Sampling from non-homogeneous solutions, particularly when using small volumes, may cause significant
measurement deviation in the data generated using all measurement technologies including spectrophotometer.
Genomic DNA, lambda DNA and viscous solutions of highly concentrated nucleic acids are common examples that
require careful attention to ensure homogeneity before sampling. Proteins are subject to denaturation, precipitation,
and aggregation and therefore also require special handling to ensure homogeneity before sampling.
Sample Measurement Accuracy and Reproducibility
Sample or aliquot non-homogeneity and/or liquid column breakage may result in erroneous or non-reproducible
results. Follow the recommendations below to ensure accurate and reproducible results:
• Ensure the pedestal surfaces are clean before opening the software. A dirty sample pedestal (i.e. a
pedestal with sample dried on to it) upon startup may cause erroneous absorbance readings (even negative
values) and signal saturation. It is good practice to clean the pedestal surfaces with de-ionized water prior
to opening the software.
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