DAD 6.1L/DAD 2.1L/MWD 2.1L user manual V6700, version 3.2
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Maintenance and Care
Advanced Cleaning
This section describes a cleaning procedure for aggressive cleaning of Light-
Guide flow cells.
Preparation of Chemicals
All chemical reagents should be of at least ACS-Grade, preferably HPLC-
Grade. This procedure involves the use of caustic and flammable reagents
(see “Safety for Users” on page 10).
Cleaning Solutions
#1
: 0.5 M Potassium Hydroxide in 100% Ethanol (briefly, 7.013g KOH in
250mL EtOH). After thorough mixing, the solution should be filtered
through a 20μm pore size filter.
#2
: 100% Methanol
#3
: Ultrapure water, Type I per ASTM D1193-99 or equivalent.
Note:
Grade 1 ultrapure water per ISO 3696 differs significantly from the
above classification.
Prerequisite
The cleaning solutions #1, #2 and #3 are readily prepared.
The flow cell is installed in a detector.
Tools
2 syringes with appropriate volumes (about 10 ml) or a peristaltic pump
Note:
It is imperative that Solution #2 immediately follow Solution #1 to
remove residue remaining on the optical components. Failure to do so will
result in poor flow cell performance.
Note:
It is recommended the peristaltic pump is configured to “pull”
through the cell to avoid possible contamination from degraded peristaltic
pump tubing. To lessen the time required for this cleaning method, large
bubbles of air can be introduced into the flow cell alternately with the clean-
ing solutions. This method uses a laminar flow profile and radial diffusion to
effectively “scrub” the inside of the flow cell.
Practical Tip:
Observe the extent of performance improvement in the Diag-
nostics window throughout the entire process.
Process with Pump
Process 1
1. Flow each cleaning solution through the flow cell in numerical order.
2. Cycle each solution for approximately 3–4 minutes, with a bolus of air
introduced between each solution. The flow direction can be reversed
between cycles to ensure thorough cleaning.
3. Repeat the procedure until there is no noticeable improvement in sam-
ple cell performance.
4. Continue with the “Final Rinsing Process” below.
Process with Syringes
Process 2
1. Disconnect the capillaries.
2. Connect the syringes to the liquid ports of the flow cell.
3. Introduce each cleaning solution into the flow cell.
4. Flush each cleaning solution back and forth between the syringes 10–
12 times.
5. Repeat the procedure until there is no noticeable improvement in flow
cell performance.
6. Continue with the “Final Rinsing Process” below.
