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Instrument Maintenance
Cleaning procedure for UltraPath 2
It is good practice to keep track of the light performance of the sensor cell by frequently
storing the reference intensities of all three pathlengths (10, 50 and 200 cm)
—
observed with
Millipore water. If variations in the baseline of more than 5-10 mAU are observed between
measurements of the same re-filled sample, the cell should be cleaned. The stored reference
signals can then be used as a guideline for how clean the cell is and how much additional
cleaning is necessary.
Reference light intensity scans of all three pathlengths are supplied with each UltraPath 2
sampling system. These scans were taken with Millipore water after the cells were rigorously
cleaned. It is recommended that the user confirm these after first receiving the instrument.
The optional cleaning kit (
WPI #501609
) can be used with the UltraPath 2 system. It consists of
three solutions numbered 1, 2, and 3. Organic contamination can be cleaned very efficiently
using these solutions in sequence, as described below. The following cleaning cycle has been
optimized for organic (
e.g.
, CDOM -type) contamination; however, depending on your
contaminant, the cleaning cycle may have to be altered.
For thorough cleaning cycles, the UltraPath 2 sample cell should be switched to the 200 cm
optical pathlength. This will ensure, that the complete cell is cleaned. For intermediate
cleaning between samples, the sample cell should be switched to the pathlength used in the
experiments.
Cleaning cycle:
1.
Rinse the cell thoroughly using ultra pure water. Obtain a new reference intensity
and take a baseline absorbance reading.
2.
Inject 3 injector volumes, separated by air bubbles, of
Solution 1 “Waveguide Cleaning solution” followed by
Solution 2 “Methanol solution” and then
Solution 3 “HCl solution”
3.
Then re-fill the UltraPath 2 with 1-2 cell volumes of Millipore water for reference and
comparison with initial absorbance signal.
4.
Repeat (2
) until scans show “little” or no change.
NOTE: Use scans for pathlength = 200cm cell as criteria for determining a clean
system
5.
Record light spectrum for each pathlength (10, 50, and 200 cm) in a separate file,
record integration time for each pathlength.
NOTE: Set integration times such that maximum counts do not exceed 45,000 to
