Metrohm 944 Professional UV/VIS Detector Vario - Manual (Page 38)

6.7 Cleaning the flow-through cell
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944 Professional UV/VIS Detector Vario (2.944.0010)
2 Connect the input capillary to a high-pressure pump or a peristaltic
pump and rinse the flow-through cell as described below; make sure
that the permissible maximum pressure of 5 MPa is not exceeded:
￭ first rinse with ultrapure water to avoid precipitates,
￭ then rinse several minutes with methanol, to dissolve the deposits,
and
￭ finally, rinse with ultrapure water for at least another 15 minutes
to wash away the dissolved deposits.
3 Observe the baseline during the last rinsing with ultrapure water.
If the baseline is only slightly noisy, then the flow-through cell is
clean.
If the noise on the baseline persists, rinse the flow-through cell once
again with another solvent (see "Rinsing the flow-through cell with
another solvent", page 30).
Rinsing the flow-through cell with another solvent
A solvent made up of a 1:2 mixture of acetic acid and isopropanol has
shown good results. Depending on the application, other solvents may
also prove efficient.
Prerequisites:
￭ Rinsing with methanol was ineffective.
￭ The input capillary is connected to a high-pressure pump or a peristaltic
pump.
1 Rinse the flow-through cell as described below; make sure that the
maximum permissible pressure of 5 MPa is not exceeded:
￭ first rinse with ultrapure water to avoid precipitates,
￭ then rinse several minutes with the selected solvent to dissolve
the deposits, and
￭ finally, rinse with ultrapure water for at least another 15 minutes
to wash away the dissolved deposits.
2 Observe the baseline during the last rinsing.
If the baseline is only slightly noisy, then the flow-through cell is
clean.
If the noise on the baseline persists, the flow-through cell must be
dismantled and cleaned manually (see "Dismantling and cleaning the
flow-through cell", page 31).