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During experiments using ion chromatography, the complex composition and concentration of samples, along with their varying physical forms, can affect the proper functioning of the instrument and lead to various malfunctions that hinder the progress of the experiments. To carry out these experiments more effectively and efficiently, this article outlines some of the common faults that occur during use and their corresponding solutions. Ion chromatography is a type of high-performance liquid chromatography (HPLC); it is a liquid chromatographic method used for analyzing anions and cations. Ion chromatography is defined as a type of liquid chromatography that utilizes the ionic nature of the substance being analyzed for separation and detection. Ion chromatography is a micro-ion analysis technique that developed gradually in the 1970s. It offers advantages such as sensitivity, speed, high accuracy, and a wide range of selection options for analyzing anions, cations, and ionic compounds, which has won the favor of many researchers and technicians. Subsequently, ion chromatographs have been widely used in industries such as environmental monitoring, petrochemicals, pesticides, and food production. Due to the complex composition and concentrations of the samples, as well as their varied physical forms, this affects the proper operation of ion chromatographs and leads to various malfunctions that hinder the progress of experiments. To enable experiments to be completed more effectively, some common faults that occur during the use of these instruments along with their solutions are outlined. 1. What are the common faults of the conductivity detector? A common fault of the conductivity detector is contamination of the cell. Cause of the failure: Pollutants mainly originate from samples that have not been properly prepared, such as those with excessively high concentrations or complex sample matrices. Fault symptom: Baseline noise increases, and sensitivity decreases. Treatment method: (1) Wash the conductivity cell with 3 mol/L HNO3 solution, and then wash it with deionized water until the pH reaches neutrality ； (2) Calibrate the conductivity cell with a 0.001 mol/L KCl solution to make the conductivity value read 147 μS. 2. What to do if the system pressure increases? An increase in pressure is usually caused by blockages in the components of the instrument. When an increase in system pressure is detected, it is necessary to start from the detector end of the flow path and check each component one by one to identify the specific unit responsible for the increased pressure. (1) When the online filter becomes clogged, replace the filter element directly ； (2) When the filter membrane at the inlet of the chromatography column is clogged, the column should be connected in reverse and rinsed repeatedly with deionized water ； (3) When the check valve and filter element become clogged, they need to be removed and ultrasonically cleaned in anhydrous ethanol for 15 to 30 minutes to remove any organic substances adhering to them. After that, they should be washed thoroughly with deionized water, then placed in a 1:1 nitric acid solution and ultrasonically cleaned for 15 minutes. Finally, they must be washed again thoroughly with deionized water before being reinstalled in their original positions and put to use. Components in high-pressure systems where clogging problems often occur include check valves, filter heads, inline filters, separation columns, and protection columns ； (4) Check whether the PEK fittings in the pipeline are tightened too tightly, as this can also lead to increased pressure. 3. How to deal with common pump failures? The common faults of analytical pumps are the formation of bubbles inside the pump and fluid leakage. Fault symptoms: increased noise at the baseline, and poor shape of the chromatographic peaks (appearance of distorted peaks). Solution: Provide an adequate amount of washing fluid to the pump, and apply a certain pressure to the washing fluid (usually less than 35 kPa). For solutions that tend to produce gas, a treatment method involving vacuum degassing first, followed by online degassing with an inert gas, can be used ； If the pump leaks, the pump seal can be replaced. 4. How to troubleshoot common faults in the use of suppressors? Suppressors play a crucial role in ion chromatographs. The performance of the suppressor has a significant impact on the analysis results. The most common failure of suppressors is leakage, which reduces the peak area (leading to decreased sensitivity) and increases the background conductivity. (1) Reduction in peak area: The main reasons for the decrease in peak area include membrane dehydration, leakage from the suppressor, poor flow in the solution pathway, and contamination of the membrane. If an inhibitor is not used for an extended period, microfilm dehydration occurs. To activate the inhibitor, a small amount of 0.2 mol/L sulfuric acid solution can be injected into the anionic inhibitor using a syringe, in the direction opposite to that of the wash fluid flow. At the same time, inject a small amount of pure water into the regeneration liquid inlet, and leave the suppressor in place for more than half an hour. Metal ions contaminating the suppressor can be cleaned with sodium oxalate. (2) High background conductivity value: In the chemical inhibition-type conductivity detection and analysis process, a high background conductivity indicates that there is some issue with the inhibitor component. Most are caused by improper operation. For example, blockages in the wash liquid or regeneration fluid flow paths, no flow of solution within the system leading to high background conductivity, or an excessively low current setting for the electrical suppressor used, etc. A decrease in exchange capacity due to membrane contamination also leads to an increase in background conductivity. A failed suppressor will cause a continuous increase in background conductivity when in use; in such cases, a new suppressor should be replaced. (3) The main reason for leakage in the leak suppressor is that the micromembrane inside the suppressor is not sufficiently hydrated. Therefore, suppressors that have not been used for a long time should have their micromembranes swollen with water before use. Additionally, it is necessary to ensure smooth flow at the outlet of the regeneration liquid; therefore, high back pressure can also cause leakage from the suppressor. Additionally, improper storage of the suppressor can cause the microfilm inside it to shrink and rupture, which also leads to leakage. 5. How should ion chromatography columns be maintained and stored? Storage of chromatography columns: Depending on the type of packing material used in the columns, the methods for storing them vary. Generally, most anion separation columns are stored under alkaline conditions, while cation separation columns are stored under acidic conditions. For long-term storage (30 days or more), first pump the storage solution into the column as required, then remove the column from the instrument, seal both ends of the column with pore-free connectors, and store it at low temperature. If not used for a short period of time, it should be turned on at least once a week and operated for 1-2 hours. Cleaning of the chromatography column: Precautions for the chromatography column – Before cleaning, the separation column should be disconnected from the system so that the waste liquid can be discharged directly. Additionally, after each cleaning, rinse with deionized water for more than 10 minutes, and then balance the system with a rinsing solution. The flow rate during cleaning should not be too high, and should be below 1 ml/min. Contamination by inorganic ions: Inorganic ions with larger ionic radii bind to the exchange groups, interfering with normal exchange separation. First, it should be considered to wash the chromatography column with a eluent of the same composition but at 10 times higher concentration. 0.1 mol/L oxalic acid is used to remove metal ions (such as Fe3+) from the anion separation column. 1-3 mol/L HCl can be used to remove certain metals (such as Al3+) from the cation separation column. Methanol or acetonitrile is commonly used to clean organic contaminants from chromatography columns, but methanol should be avoided when using cation separation columns with carboxyl groups. In the cleaning solution for chromatography columns filled with ion exchange resins of low cross-linking degree (cross-linking degree less than 5%), the concentration of organic solvents should not exceed 5%. Cleaning of the chromatography column: Precautions for the chromatography column – Before cleaning, the separation column should be disconnected from the system so that the waste liquid can be discharged directly. Additionally, after each cleaning, rinse with deionized water for more than 10 minutes, and then balance the system with a rinsing solution. The flow rate during cleaning should not be too high, and should be below 1 ml/min. Contamination by inorganic ions: Inorganic ions with larger ionic radii bind to the exchange groups, interfering with normal exchange separation. First, it should be considered to wash the chromatography column with a eluent of the same composition but at 10 times higher concentration. 0.1 mol/L oxalic acid is used to remove metal ions (such as Fe3+) from the anion separation column. 1-3 mol/L HCl can be used to remove certain metals (such as Al3+) from the cation separation column. Methanol or acetonitrile is commonly used to clean organic contaminants from chromatography columns, but methanol should be avoided when using cation separation columns with carboxyl groups. In the cleaning solution for chromatography columns filled with ion exchange resins of low cross-linking degree (cross-linking degree less than 5%), the concentration of organic solvents should not exceed 5%.