Section 4-Common Module Functions
3. General
Operation
The Sample Retention System
Basic Use
The main steps for using the sample retention system are listed below:
1. With the sampling arm open, pipette the sample onto the lower
measurement pedestal.
2. Close the sampling arm and
initiate a spectral measurement
using the operating software on the
PC. The sample column is
automatically drawn between the
upper and lower measurement
pedestals and the spectral
measurement made.
3. When the measurement is
complete, open the sampling arm and
wipe the sample from both the upper
and lower pedestals using a soft
laboratory wipe. Simple wiping
prevents sample carryover in
successive measurements for
samples varying by more than 1000
fold in concentration. See
www.nanodrop.com for performance
data on sample carryover.
Cleaning the Sample Retention System
Wiping the sample from both the upper and lower pedestals (as shown above) upon completion of each sample measurement is usually
sufficient to prevent sample carryover and avoid residue buildup. Although generally not necessary, 2 ul water aliquots can be used to
clean the measurement surfaces after particularly high concentration samples to ensure no residual sample is retained on either
pedestal. After measuring a large number of samples, however, it is recommended that the areas around the upper and lower pedestals
be cleaned thoroughly. This will prevent the wiping after each measurement from carrying previous samples onto the measurement
pedestals and affecting low-level measurements. A final cleaning of all surfaces with de-ionized water is also recommended after the
user’s last measurement.
Decontamination of Measurement Pedestals
If decontamination is necessary, a sanitizing solution, such as a 5.25% solution of sodium hypochlorite (bleach – freshly prepared), can
be used to ensure that no biologically active material is present on the measurement pedestals. The metal fiber optic fittings are made
from 303 stainless steel and are resistant to most common laboratory solvents (see “Solvent Compatibility” appendix).
Special Cleaning Requirements for Proteins
Proteins and solutions containing surfactants can “un-condition” the measurement pedestal surfaces so that the liquid column does not
form well with 1ul samples. If this occurs, “buff” the measurement pedestal surfaces by rubbing each with a dry laboratory wipe 30-40
times. This will “re-condition” the surface allowing the liquid sample column to form.
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