Troubleshooting Chromatogram Problems

i-Series Virtual Advisor

Add Bookmark

Symptom Cause Solution
The peak retention times vary Is the needle seal worn? If the needle seal is worn, replace it.

Reference: Replacing the Needle Seal
The peak retention times vary Is the needle or tubing clogged? Backwash the high-pressure valve. Replace the needle or the tubing if backwashing has no effect. Rinse the inside of the needle with mobile phase solution. Replace the needle or the tubing if rinsing has no effect.

Reference: Replacing the Needle - Part 1 and Part 2
The peak retention times vary Is the mobile phase flow rate of the pump stable? Check whether the pump operates normally and take corrective action.
The peak retention times vary Is the flow line rinsing sufficient? Purge or rinse the flow line.
The peak retention times vary Is the column deteriorated?  Check whether the column oven operates normally, and if there is an abnormality, take corrective action. Check the column under the known analysis conditions, and if it has deteriorated, replace it.
The peak retention times vary Is the check valve dirty? Pump 2-propanol to rinse the check valve. Note that, when using a buffer solution, first pump purified water to rinse the check valve. Then pump 2- propanol to rinse. If rinsing has no effect, perform an ultrasonic rinse of the check valve or replace it.
The peak retention times vary Has the temperature of the column changed? Use the column oven.
The peak retention times vary Has the flow rate or the composition of the mobile phase changed?  Check the pump and the mobile phase solution.
The peak retention times vary Does the ambient temperature vary much?  Install the instrument in a place where the temperature does not change excessively.
The peak retention times vary Does the liquid flow from the flow line?  Retighten the connection part. If retightening does not stop the liquid leak, replace the connection part.
The peak shape is abnormal (e.g., the peak widths are too large, tailing, etc) Is there a dead volume in the connection part of the flow line? Inspect the connection part, and if there is a dead volume, connect properly.
The peak shape is abnormal (e.g., the peak widths are too large, tailing, etc) Is the tubing of the pump and column reversed? Configure the tubing correctly.
The peak shape is abnormal (e.g., the peak widths are too large, tailing, etc) Is the needle or tubing clogged? Backwash the high-pressure valve. Replace the needle or the tubing if backwashing has no effect. Rinse the inside of the needle with mobile phase solution. Replace the needle or the tubing if rinsing has no effect.

Reference: Replacing the Needle - Part 1 and Part 2
The peak shape is abnormal (e.g., the peak widths are too large, tailing, etc) Does liquid flow from the flow line? Retighten the connection part. If retightening does not stop the liquid leak, replace the connection part.
No peak appears Is there the required amount of sample in the sample vial? Add the required amount of sample to the sample vial.
No peak appears Is the hole at the tip of the needle plugged by the bottom of the sample vial?  Change the needle stroke to a smaller value.
No peak appears Is the flow line through which the sample is injected clogged? Backwash the flow line. Inspect the flow line, and if it is clogged, replace the part.
No peak appears Is the content of the time program correct? Check the time program and correct it.
No peak appears Is the column deteriorated? Check the column under the known analysis conditions, and if it has deteriorated, replace it.
No peak appears Does the mobile phase solution flow? Check whether the pump operates normally and take corrective action.
No peak appears Does the detector operate normally?  Check whether the detector operates normally and take corrective action.
A ghost peak occurs Is the rinsing port dirty? Set the "Rinsing volume," the liquid replacement volume in the rinsing port, to a min. of 450 μL.
A ghost peak occurs Is the rinse liquid being pumped? Check for rinse liquid.
A ghost peak occurs Is the high-pressure analysis flow line dirty, including the needle and sample loop? Rinse according to the following procedure. 1 Deliver a 17% phosphoric acid solution at a flow rate of 1 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa) 2 Deliver purified water at a flow rate of 9 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa)
A ghost peak occurs Does previous rinse liquid remain in the rinse liquid flow line? Rinse the flow line and replace with the rinse liquid to be used.
A ghost peak occurs Does previous mobile phase solution remain in the mobile phase flow line?  Rinse the flow line and replace with the mobile phase solution to be used.
A ghost peak occurs Are the tubing, line filter, and suction filter dirty?  Inspect the suction filter for clogging. Additionally, rinse according to the following procedure.1 Deliver a 17% phosphoric acid solution at a flow rate of 1 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa) 2 Deliver purified water at a flow rate of 9 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa)
The retention time of the target component significantly differs from when measured in another system Is the temperature of the column off?  Validate the temperature accuracy of the column oven. If NG, adjust the temperature accuracy.
The baseline drifts Was the measurement conducted immediately after the lamp was illuminated? It takes the instrument 1 hour after the lamp illuminates in order to become stabilized. When conducting a high sensitivity analysis, start the measurement about 1 to 1.5 hours after the lamp illuminates.
The baseline drifts Is the flow line dirty? Rinse the tubing and the detector of the instrument sufficiently according to the following procedure. 1 Deliver a 17% phosphoric acid solution at a flow rate of 1 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa) 2 Deliver purified water at a flow rate of 9 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa)
The baseline drifts Is the detector faulty? Check whether the detector operates normally, and if there is an abnormality, take corrective action.
The baseline drifts Is liquid leaking from the flow cell? Check for liquid leaking from the connection parts of the cell inlet tubing / outlet tubing or the cell window. If liquid is leaking, disassemble and clean.

Reference: Disassembling and Cleaning the Flow Cell
The baseline drifts Is a strong air current being blown, such as from an air conditioner? Use a partition, etc., so that no air current is blown directly on the instrument. Install in a location where temperature variations are minimal.
The baseline drifts Have air bubbles accumulated in the flow cell? Check whether the baseline changes significantly if the cell outlet tubing is held down. Alternatively, visually check if air bubbles are flowing into the flow cell. If air bubbles are flowing, disassemble and clean the flow cell.

Reference: Disassembling and Cleaning the Flow Cell
The baseline drifts Has the room temperature changed? Stabilize the room temperature. Install in a location where temperature variations are minimal.
The baseline drifts Has the mobile phase flow rate changed? Check whether the pump operates normally, and if there is an abnormality, take corrective action.
The baseline drifts Does the ambient temperature vary much?  Install the instrument in a place where the temperature does not change excessively.
The baseline drifts Are the tubing, line filter, and suction filter dirty? Inspect the suction filter for clogging. Additionally, rinse according to the following procedure.1 Deliver a 17% phosphoric acid solution at a flow rate of 1 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa) 2 Deliver purified water at a flow rate of 9 mL/min for about 30 minutes. (Pumping pressure: 1 MPa to 5 MPa)
The baseline drifts Are the mobile phase and column statuses stable?  Check whether the drift decreases if pumping is stopped or by changing to an air cell*3. If it does, the mobile phase may be mixed with impurities or the column may not be well equilibrated. Perform checks including for the mobile phase, column, and analysis condition.
The baseline shifts Is there any backlash or gap in the installation of the lamp or the flow cell? If there is backlash or a gap, reinstall the parts in their proper status.
The baseline shifts Is liquid leaking from the flow cell? Check for liquid leaking from the connection parts of the cell inlet tubing / outlet tubing or the cell window. If liquid is leaking, disassemble and clean.

Reference: Disassembling and Cleaning the Flow Cell
The baseline undulates Is a strong air current being blown, such as from an air conditioner?  Use a partition, etc., so that no air current is blown directly on the instrument. Install in a location where temperature variations are minimal.
The baseline undulates depending on pump stroke Does liquid flow from the plunger seal? Replace the plunger seal. When the lifetime of the plunger seal is extremely short, replace the plunger as well. Maintenance procedures will vary depending on your system type.

Reference: Cleaning and Replacing the Plunger and Diaphragm, Inspecting the Plunger and Diaphragm, Replacing the Plunger and Diaphragm, Replacing the Plunger Seal
The baseline undulates depending on pump stroke Are there air bubbles inside the pump head? Press [PURGE] to eliminate the air bubbles or connect a syringe to the end connection of the drain tubing to remove the air bubbles.
The baseline does not vary Is the range set to "0"? Set a proper range.
The baseline does not vary Is the lamp turned off?  Set [LAMP] to [D2]. The lamp will be illuminated.
The baseline does not vary Do signals scale out to the negative side (or the positive side)? Press the zero button from the "Analysis" screen. Zero position adjustment will be performed. Also, set the "Perform auto zero at analysis start" setting to "Enabled".
Noise is excessive Is the lamp deteriorated? Even if an air cell has a small intensity, or if the lamp usage time is longer than 2,000 H, replace the lamp.

Reference: Replacing the D2 Lamp - PDA Detector / UV Detector
Noise is excessive Is the intensity insufficient Check the intensity. If the intensity is low, take the corrective action for when "Intensity is low."
Noise is excessive Is a strong air current being blown, such as from an air conditioner Use a partition, etc., so that no air current is blown directly on the instrument. Install in a location where temperature variations are minimal.
Noise is excessive Does external vibration have an effect? Eliminate potential sources of vibration
Regular spike-shaped noise appears Have air bubbles accumulated in the flow cell? Check whether the baseline changes significantly if the cell outlet tubing is held down. Alternatively, visually check if air bubbles are flowing into the flow cell. If air bubbles are flowing, disassemble and clean the flow cell.

Reference: Disassembling and Cleaning the Flow Cell - PDA Detector / UV Detector
Regular spike-shaped noise appears Are the pulsations of the pump excessive?  Check whether the noise disappears if pumping is stopped. Check the pumping condition (pulsation), and if the pulsation is excessive, rinse the flow line.
Irregular spike-shaped noise appears Have air bubbles accumulated in the flow cell? Check whether the baseline changes significantly if the cell outlet tubing is held down. Alternatively, visually check if air bubbles are flowing into the flow cell. If air bubbles are flowing, disassemble and clean the flow cell.

Reference: Disassembling and Cleaning the Flow Cell - PDA Detector / UV Detector
Saw-shaped noise appears (the baseline drifts in the positive direction and suddenly returns in the negative direction, and this behavior is repeated)  Have air bubbles accumulated in the flow cell? Check whether the baseline changes significantly if the cell outlet tubing is held down. Alternatively, visually check if air bubbles are flowing into the flow cell. If air bubbles are flowing, disassemble and clean the flow cell.

Reference: Disassembling and Cleaning the Flow Cell - PDA Detector / UV Detector
Saw-shaped noise appears (the baseline drifts in the positive direction and suddenly returns in the negative direction, and this behavior is repeated)  Are the pulsations of the pump excessive?  Check whether the noise disappears if pumping is stopped. Check the pumping condition (pulsation), and if the pulsation is excessive, rinse the flow line.
When using 2 wavelength mode, noise is 10 times more than 1 wavelength mode Was the measurement performed with the wavelength where the variation in the mobile phase absorbance is extremely excessive? Because the instrument detects 2 wavelengths by scanning gratings, measurement wavelengths vary within the range of wavelength reproducibility (±0.1 mm), thus making noise. Change the measurement wavelengths to smaller wavelengths whose changes cause as small a variation in mobile phase absorbance change as possible. Also, increase the response value within the allowable range.