The Metrohm Suppressor Module (MSM) is used for chemical suppression in anion and cation analysis. This increases the analytical performance.
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If the MSM is loaded with contaminants for an extended period, the standard regeneration solution is not sufficient. The performance of the suppressor is continously reduced, which can be observed by an increase of the baseline or asymmetric peak forms.

In these cases, treat the MSM rotor on all three chambers as follows:

For the rotors

MSM-HC Rotor A (6.2842.000) / MSM Rotor A (6.2832.000) / MSM-LC Rotor A (6.2844.000) / SPM Rotor A (6.2835.000)

the procedure is as following:

The inlet capillary for regeneration (regenerant) is connected via the coupling 6.2744.040 to the high-pressure pump. In this way, all three chambers can be rinsed in a reverse flow of 1 mL/min.

MSM / MSM-LC / SPM -> 15 min
MSM-HC -> 45 min

The following solutions are recommended:
- Contamination with heavy metals or with increased backpressure: 1 mol/L H2SO4 + 0.1 mol/L oxalic acid
- Contamination with organic cationic complexing agents: 0.1 mol/L H2SO4 / 0.1 mol/L oxalic acid / acetone 5%
- Heavy contamination with organic substances: 0.2 mol/L H2SO4 / acetone more than 0.2 mol/L H2SO4 / acetone more than 20%

The rotor must then be rinsed again with water for all three positions.

Additional information:
8.110.8010.ML (MSM, MSM-HC, MSM-SPM)
8.110.8008.ML (MSM-LC)

For the MSM-HC rotor C (6.2842.200):

Option A:
1. Stop the flow of the regenerant.
2. Flush the system with Eluent until the suppressor chamber is completely exhausted (recognizable by a significant increase of the conductivity signal). With standard conditions this can take up to 240 minutes.
3. Step to the next chamber and repeat step 2.
4. Repeat step 3 for the last suppressor chamber.
5. As soons as all three suppressor chambers are completeley exhausted start the regeneration feed again.
6. Equilibrate the system as normal.

Option B:
1. Flush all rotor chambers with about 150 mL 2 mol/L HNO3 with a maximum flow rate of 5 mL/min using the 2 mL Dosing burette or the peristaltic pump. Step the MSM rotor every 5 minutes.
2. Flush each rotor chamber with 50 mL of the standard regenerant.
3. Equilibrate the system as normal.

Additional information:
8.110.8021ML (MSM-HC Rotor C)