Cleaning the flowcell
The high sensitivity of the detector and the low volume of the
flowcell make it imperative that a high standard of solvent purity
and general system cleanliness be maintained. A contaminated
flowcell can lead to noise and drift problems that are often
mistakenly attributed to other areas of the system.
The cell can be cleaned in-situ (in place) quite successfully by
using the following procedure;
1. Flush the system thoroughly using HPLC grade water to
remove any trace of organic solvents.
2. After the system has been rinsed with water, pump 25%
phosphoric acid through the flowcell. This acid is prepared by
diluting one part of concentrated phosphoric acid with three
parts of HPLC grade water.
3. After pumping 50ml of the 25% acid through the cell at 1-2
ml/min, rinse by pumping 100 to 200ml of HPLC grade water
through the system. Do not allow the acid to remain in the
cell for more than one hour. Dispose of the acid in accordance
with approved waste disposal procedures.
4. Do a final rinse with acetonitrile or methanol.
The frequency for cell cleaning depends upon the cleanliness
maintained during routine operation.
When making or breaking solvent line fittings, care should be
taken to prevent any contamination of exposed fittings. Tubing
should be sealed or capped when not actually connected. Thread
lubricants should never be applied to compression fittings.
The external windows of the flowcell can be cleaned with a dry,
clean source of compressed air or nitrogen. Remove the flowcell
and carefully blow any dust or contamination from the external
windows. Replace the flowcell, ensuring that the sample and
reference beam windows are not obstructed.