Annual Maintenance - Ion Chromatography

Introduction

Annual maintenance is a critical milestone in the lifecycle of ion chromatography systems, bringing together comprehensive inspections and preventative service actions. While routine weekly, monthly, and quarterly tasks support day-to-day stability, annual maintenance addresses long-term wear, system optimization, and readiness for continued operation in demanding analytical environments. This article outlines Metrohm's recommended annual maintenance practices for ion chromatography systems, emphasizing thorough evaluation steps that help maintain data integrity, extend instrument lifespan, and prevent costly unplanned downtime. 

Replacing the MCS Scrubber Cartridge

1. Remove the protective cap. 

   

2. Attach the included dust filter to the tip. 

   

3. Remove the sticker at the base. 

   

   Please note: Leaving the sticker on will prevent the cartridge from functioning. 

4. Attach the "air in" line for the MCS to the dust filter. 

   

5. Clip the cartridge in place using the clips on its holder. 

   

   

Dosino Maintenance 

Separate the Dosino and Dosing Unit

1. The piston MUST be all the way up and in Port 2 (the number 2 should display in the Port window).
   1. The easiest way to do this is to power cycle the controlling device where the Dosino is plugged in. 
   2. Alternatively, you can use Manual control to select the Dosino and choose "fill" from Port 2. 

2. Once the Dosing unit is in the correct position, power down the controlling device and disconnect all tubing from the Dosing unit, then unplug the Dosino from its controlling device. 

   Note: Be sure to note where all the tubing is connected, as well as where the Dosino was plugged in, so that everything may be reconnected in the exact same configuration. 

3. Once disconnected, the Dosino and Dosing unit may be separated by gently twisting the Dosino to the "unlock" position and removing it from the Dosing unit. 

   Note: NEVER use force when disconnecting the devices from one another. If they are stuck together, contact Metrohm Technical Support at Metrohm Technical Support. 

   

Disassembling the Dosing Unit

1. Release the green housing by pressing on the locking button and twisting counterclockwise. Lift off and set aside. 
2. Remove the centering tube with the glass cylinder inside. 

3. If you are replacing the cylinder tube, this may be discarded and you can proceed to lubrication and reassembly. If you are cleaning the existing cylinder, continue with the following instructions. 

   Note: If the cylinder is stuck to the distributor disc, do NOT separate by force. Place into warm water until loosened. Gentle sonication may also be used. 

4. Remove the plastic centering tube from the glass cylinder and set aside. 
5. Use piston pliers to remove the piston peg. Set aside and ensure the peg is NOT set on its side (invert pliers holding peg and set upright with peg in the air). 

6. Rinse glass cylinder with ultrapure water making sure the valve disc isn't blocked. Dry with lint-free cloth. 

   Note: NEVER use solvent, brushes, or abrasive cleaners in order to avoid damaging components. NEVER remove the black cylinder disc from the glass cylinder. NEVER remove the white distributor disc from the fixing ring. 

   

Lubricating the Glass Cylinder on Dosing Unit

Always wear gloves to avoid contamination.

1. Using the supplied Metrohm grease, lubricate the underneath of the green housing and top of the centering tube where they contact each other. 

2. Put a VERY fine coat of grease on the sides of the piston peg as well as the surface of the black valve disc. 

   Note: Grease layer should be so fine that a fingerprint isn't visible. Best practice is to wipe a thin layer on and then gently wipe the surface with a lint-free cloth. 

   

Reassembling the Dosing Unit

1. Place new or cleaned glass cylinder on a flat, stable surface. 

2. Insert piston peg until the very beginning of the flat side is inside the cylinder. Most of the top will still be protruding. 

   

3. Place the centering tube over the piston, being sure to match the tab thickness with the slots on the black cylinder base. 

   

4. Ensure that the piston plunger is centered in the opening. 

5. Place the green housing over the centering tube and push gently downwards until flush with the table surface. 

   

6. Place the assembled centering tube onto the distributor being sure that it doesn't fall apart. Use the ridges for alignment. 
7. Place the green housing over the centering tube and align the ridges. 
8. Hold the white ring on the distributor and twist the green housing clockwise until the locking buttons clicks into place. 

9. Use the piston pliers horizontally to push down on the top of the assembly to make sure everything is flush.

   

    

10. Once assembled, make sure the two arrows (one on the clear centering tube, another on the green housing) are pointing towards one another. If not, manually adjust them by twisting the centering tube within the housing. 

    

Reattach the Dosino and Dosing Unit

1. Make sure the Dosing unit arrows are aligned and the piston is flush with the housing. 

   

2. Make sure small plastic ribs are aligned on the base of the Dosino housing. If not, manually twist the drive disc until aligned. 

   

3. Slide the guide pegs into the holes on top of the green housing and gently twist clockwise into the "lock" position. 

   

4. Reattach all tubing, plug in the Dosino at the controlling device and power on. Purge air from Dosing unit as needed. 

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.