Weekly Maintenance - Ion Chromatography

Introduction

Ion chromatography systems are built for precision and long-term reliability, but even the most robust instruments depend on consistent care. Performing a few simple maintenance checks each week helps ensure stable baselines, reliable retention times, and uninterrupted operation. This article outlines Metrohm's recommended weekly maintenance practices for ion chromatography systems, focusing on small, preventative steps that protect performance, extend component life, and reduce unplanned downtime. 

Check, clean and refill rinse bottles on autosampler (if used)

1. Before beginning a determination series:

   1. Empty rinse bottles. 
   2. Rinse with a 1:4 ratio of acetone and water. 
   3. Tripe rinse & refill with ultrapure (18MΩ) water. 

   4. Do not leave screw caps (depicted) on the bottle when operating.

       

   Please note: Not routinely emptying and rinsing these bottles can result in contamination and carry-over showing up in analyses. 

Changing the Ultrafiltration Membrane

1. Remove screws and disassemble the ultrafiltration cell. 

    

2. Using provided tweezers, remove the old filtration membrane and discard. 

    

3. Rinse cell with ultrapure (18MΩ) water. Clean with cotton swab if necessary. Make sure no discolorations or residue remain in the cell or cell grooves. 

   Please note: Use only ultrapure water or ethanol to clean the cell. Other solvents (i.e. acetone) will damage it. 

    

4. Locate replacement filtration membrane (6.2414.020 or 6.2414.030). Do not confuse it with the white cardboard or blue wax separators. 

   Please note: Handle membrane with tweezers to avoid contamination. 

    

5. Place membrane in clean beaker filled with ultrapure (18MΩ) water and soak for 2 minutes. 

    

6. Use tweezers to place membrane in cell. Be careful not to tear the filter. 

    

7. Reassemble cell as shown below (screws pass through non-threaded half of cell first). 

    

8. Carefully tighten screws in a star pattern to avoid cracking the cell. Do not over tighten or flow may be impeded. 

    

Checking Operating Pressure (MagIC Net)

1. In MagIC Net, click on the Workplace button. 
2. Select the desired method. 
3. Click the Start HW button. 
4. Allow the system to run for 30 minutes, or until baseline is stable. 
5. Record the operating pressure in a laboratory log and compare to previous readings. 

6. A gradual increase in pressure by 1+MPa is a sign that the RP2 guard disk and filter or guard column need to be changed. 

   Pressure conversions: 

   1MPa = 145psi

   1MPa = 10 bar

Checking and Preparing New Eluent

1. Consult your application note or SOP for instructions on your specific mobile phase. 
2. Be sure to degas source water or use IC with in-line eluent degassing. 
   1. Eluents with organic solvent modifiers >5% require additional off-line degassing. 
   2. Carbohydrate eluents must be degassed for at least 60 minutes to remove all traces of carbonate and should be kept in plastic bottles for analysis. 
3. Create eluent from high purity salts or eluent concentrates. 
   1. Preparation from eluent concentrates is generally easier. 
   2. Prepare fresh eluent every 2-4 weeks or per Application Note or SOP instructions. 
   3. Carbohydrate eluent must be prepared fresh daily and stored in a plastic container. 

Checking Flow from Autosampler Peristaltic Pump Tubing (MagIC Net)

1. Click on the Manual Icon in MagIC Net. 

    

2. Select the Tower tab on the autosampler, select one of the special beakers or their numerical position and click Start. 

3. Select the lift position to the Work position or 125mm (standard Metrohm vials) and click Start. 

    

    

4. Click on the peristaltic tab of the autosampler. Press the Start button and time the length of the pump time with a stopwatch, collecting the flow out of the peristaltic tubing with a graduated cylinder or test tube. Press Stop when done. Divide the volume of liquid collected by the number of minutes timed to get the flow rate in mL/min. 

    

Checking Flow from MSM Peristaltic Tubing

1. In Manual control, turn on the MSM peristaltic pump. 
2. Disconnect at the outlet of the peristaltic tube and place outlet in graduated tube or cylinder. 
3. Start your timer and collect flow until an accurate volume can be read in your cylinder. 
4. Stop the peristaltic pump and the timer. Divide the volume collected by the time to get mL/min. 
5. Compare to tubing chart below and replace tubing if flow is less than 80% specified volume. 
6. Replace in-line filter when replacing tubing. 

Changing Peristaltic Pump Tubing

1. Push down contact pressure levers to loosen them completely. 

   

2. Push bottom right of snap action lever to release the cartridge (hinges at left). Remove tubing cartridges from IC. 

   

3. Disconnect lines at inlet and outlet of peristaltic pump tubing. Remove peristaltic tubing from IC. Remove barb fittings from end of tubing. Insert them into new peristaltic tubing of the same kind. 

   

4. Thread new peristaltic tubing through center groove of tubing cartridge. Stoppers should fit in a matching indentation in cartridge. 

   

5. Replace tubing cartridges in IC. Carefully reconnect lines. Ensure contact pressure lever is sufficient to deliver proper flow. 

   

Additional Support

If you encounter any issues or need additional help, please submit a support ticket through Metrohm Technical Support. 

For additional training on any of these topics, explore our available Metrohm Ion Chromatography Training courses or learn more about our Metrohm Custom Training options.