Ten key points for daily maintenance and common troubleshooting of ion chromatographs

Rinse solution management

Prepare the eluent with high-purity reagents, and the ultra pure water resistivity should be greater than 18.2MΩ · cm。

The rinse solution needs to be filtered through a 0.45 μ m membrane and subjected to ultrasonic degassing. It is recommended to replace the carbonate rinse solution every 3-5 days.

The liquid suction filter head should be replaced every 3 months, and should be replaced immediately if it changes color. Before operation, it should be rinsed with detergent and dust-free gloves should be worn.

High pressure pump maintenance

Before operation, confirm that the rinsing solution pipeline is connected correctly and the liquid volume is sufficient to avoid dry running and damaging the sealing components.

Before shutting down, rinse the pump head with ultrapure water to prevent liquid leakage caused by crystallization; When the shutdown exceeds 15 days, the system needs to be flushed with a 20% methanol aqueous solution.

Replace sealing components such as piston seals and zirconium piston rods once a year.

Online filter maintenance

Replace the filter element every 3 months or promptly when the background pressure rises to ensure that the system is free of particle blockage.

Quantitative loop and pre concentration column management

The anionic quantitative ring is replaced every 2 years, and the cationic quantitative ring is replaced every 1 year.

When using a pre concentration column, be sure to fill the sample in the opposite direction to the direction of the eluent to avoid reverse operation.

Column protection and storage

Select the appropriate protective column based on the sample type, strictly follow the direction of the chromatographic column flow path, and prohibit reverse flushing.

When it is not used for a long time, fill it with rinsing solution and seal it according to the instructions to prevent drying or microbial growth.

Replace the chromatography column once a year (with an anion column lifespan of approximately 500 injections).

Suppressor maintenance

Use PTFE material capillary tube to connect the flow path, and the joint should not be too tight.

Replace the MSM online filter cartridge every 3 months and replace the CO ₂ absorption tube filling once a year.

When not in use for a long time, it is necessary to inject the washing solution in reverse to activate the biofilm, in order to avoid dehydration or contamination.

Peristaltic pump tube management

Rotate the pump tube position every month and replace it as a whole every 2-3 months to prevent aging and unstable flow rate.

Maintenance of conductivity detector

The pressure during flushing should be less than 5MPa, and it is forbidden to cut the inlet and outlet pipelines arbitrarily.

Do not disassemble the detector casing by yourself. Contact a professional engineer for assistance in case of malfunction.

environmental control

The laboratory temperature is maintained at 25 ℃; 2 ℃, humidity<70%, avoid corrosive gases (such as Cl ₂) from contacting metal parts.

Daily cleaning and recording

Test blank runs daily and observe baseline stability.

Clean the injection needle and automatic injector tray weekly, and replace the 0.22 μ m online filter once a month.

Detailed records of maintenance content, replacement parts, and fault phenomena, and establishment of traceable maintenance files.

Common troubleshooting guide

Abnormal system pressure

High pressure: Check if the pump head sealing ring is worn and leaking, verify if the chromatography column is blocked by backwashing, and investigate if the pipeline is bent or the filter is blocked.

Low pressure: Confirm the sealing of the pump piston, check if the mobile phase is sufficient or volatile, and identify system leakage points.

Pressure fluctuation: Check if the one-way valve of the pump head is damaged, verify if the calibration of the proportional valve is ineffective, and eliminate bubble interference.

Baseline issue

Baseline noise (rule): Check whether the mobile phase is fully degassed and check whether the connection of the pump's rear pipeline is tight.

Baseline noise (irregular): Replace the contaminated mobile phase, clean the conductivity cell electrode, and supplement the reference electrode filling solution (such as 3MKCl solution).

Baseline drift: Stable column temperature (temperature control accuracy&plusmn;); Within 0.5 ℃, recalibrate the suppressor or pump proportional valve.

Retention time offset

Check whether the flow matching ratio has changed (such as the fluctuation of suppressor current affecting the pH of the eluent), and confirm whether the column temperature is stable.

Check for system leakage or bubble interference to ensure that the pump delivers the rinsing solution at the set flow rate.

Abnormal peak shape

Frontline peak/tailing peak: Clean or replace the blocked quantitative ring, remove contamination by backwashing the chromatographic column, and adjust the sample solvent to match the mobile phase.

Fork peak: Replace the contaminated protective column or analytical column to ensure that the sample solvent and flow are mutually soluble.

Peak broadening: Reduce the injection volume, decrease the viscosity of the mobile phase, and optimize the volume of the detection cell.

Detector malfunction

Baseline sawtooth fluctuation: Clean the conductivity cell electrode, supplement the reference electrode filling solution, and investigate the leakage of the detection cell.

High background conductivity: Adjust the suppressor current (anion suppression current 50-100mA) and replace the depleted regeneration liquid storage tank.

Data processing exception

Chromatogram without peak shape: Check if the data acquisition channel is enabled and adjust the range to automatic mode.

Poor repeatability of peak area: Optimize integration parameters (threshold set to 2-5 times baseline noise) to improve chromatographic separation.