Daily Maintenance of Protein Purification Systems

Here, taking the AutoPure protein purification system from Inscinstech as an example, we briefly outline the daily maintenance and startup/shutdown precautions (which can also be applied to protein purification systems from other brands). May everyone take preventive measures to keep the instrument in good condition for years to come.

 

1. Daily Maintenance

Flow Path Maintenance (Daily)

◇Wipe down the exterior to remove any solution or salt crystallization, preventing corrosion of the instrument's surface and components.  

 (Note: Severe rust or corrosion often starts from unnoticed spills left uncleaned over time.)

◇Filter all solutions and samples before use. A 0.45 μm (or equivalent) filter is recommended to prevent:  

  - Clogging in the flow path  

  - Contamination of chromatography column resin  

  - Damage to detectors  

◇Inspect tubing and fittings for cracks or leaks. Pay special attention to Peek tubing—larger inner diameter tubes (e.g., 1 mm white tubing) are more prone to kinking.  

(Prevents leaks, overpressure, sample loss, and column damage.)

◇Post-run flushing protocol:

  1. Rinse the system thoroughly with pure water until baselines stabilize.  

  2. Follow with 20% ethanol for system storage to prevent microbial growth and performance degradation.  

  3. Important:When switching from salt-containing buffers to 20% ethanol storage, flush with pure water first to avoid microbubble formation in the system.  

(This routine ensures long-term flow path integrity and consistent performance.)

 

pH Meter

◇ Calibrate the pH meter before use (always calibrate with a point close to 7 first).  

◇ After use, remove the pH electrode, rinse it with pure water, wipe it clean, and store it in protective solution (saturated KCl solution at pH 4.0).  

◇ The tip of the pH electrode consists of a thin glass membrane—avoid impact, contamination, or drying out, as this can damage the electrode.  

(Proper maintenance ensures accurate measurements and extends the electrode's lifespan.)

 

System Pump Maintenance

◇ Before each use or when changing buffers, purge any air bubbles from the pump chamber and tubing via the purge valve (use a large syringe to slowly withdraw at least 5 mL of liquid).

Failure to do so may compromise flow rate accuracy or even prevent proper liquid delivery.

 

Weekly Maintenance

Flow System

◇ Check and clean the buffer inlet filter screen - If significant contamination is observed, remove the filter for ultrasonic cleaning.

◇ Inspect the pump post-rinse solution - Verify there is no notable increase/decrease in volume or cloudiness. If abnormal, replace the rinse solution (20% ethanol) and re-mark the liquid level.

 

 

Monthly System Maintenance

Whole Machine Section

◇ 1M NaOH Cleaning

Set both Pump A and Pump B to 50% concentration

Flush at 10% of the system's maximum flow rate for ~20 minutes

Immediately rinse thoroughly with pure water until conductivity approaches 0

◇ 75% Ethanol Disinfection

Set both Pump A and Pump B to 50% concentration

Flush at 10% of maximum flow rate for ~2 minutes

Rinse completely with pure water

◇ In-line Filter Membrane Maintenance

After removal, ultrasonically clean with 0.5M NaOH for 10 minutes

 

Back Pressure Valve Maintenance

◇ Pressure Parameter Check

Compare pressure readings between in-line and removed configurations

Standard parameter: 0.14MPa ±0.05MPa at 5ml/min flow rate

◇ Troubleshooting

If pressure exceeds specification:

Perform ultrasonic cleaning

Adjust valve setting

Replace if necessary

For uncertain cases, consult local service engineers

 

Semi-Annual Maintenance

Pressure Sensor

◇ Zero Point Verification

   - Disconnect both front and rear pressure sensor fittings  

   - Verify displayed pressure reading is at zero point  

   - If deviation exceeds ±0.02MPa, contact after-sales engineer for on-site calibration  

 

UV Detector

◇ Flow Cell Cleaning Protocol

   1. Inject 10% detergent solution (e.g., Decon90, SDS) into UV flow cell  

   2. Flush back-and-forth several times, then let stand for 20 minutes  

   3. Rinse thoroughly with pure water  

   4. Repeat process using either ethanol or 1M NaOH solution  

 

pH/Conductivity Detector

◇ Flow Cell Maintenance

   - Remove pH electrode and install blind plug  

   - Flush pH flow cell with 1M NaOH for 30 minutes  

   - Rinse thoroughly with pure water  

◇pH Electrode Restoration (When response is slow/inaccurate)

   1. Salt Deposits: Alternate washing with 0.1M HCl → 0.1M NaOH → 0.1M HCl (5 min intervals, water rinse between steps)  

   2. Grease/Oil Contamination: Clean with 1% SDS solution followed by water rinse  

   3. Protein Fouling: Treat with 1% protease in 0.1M HCl solution followed by water rinse  

(This comprehensive biannual maintenance ensures detector accuracy and prolongs component lifespan.)

 

Preventive Maintenance

◇ Conduct a thorough and detailed maintenance of the entire system

◇ Reduce the risk of malfunctions and improve instrument performance

◇ Extend the service life of the equipment

◇ Maintenance interval: Annually

 

2. Long-Term Shutdown Precautions

● For equipment in room-temperature laboratory environments:  

◇ Thoroughly clean the exterior surfaces, especially salt residues.  

◇ Flush with 1M NaOH solution (50% Pump A + 50% Pump B) at 10% of maximum system flow rate for ~20 minutes, then immediately rinse with pure water until conductivity approaches 0.  

◇ Flush with 75% ethanol solution (50% Pump A + 50% Pump B) at 10% of maximum flow rate for ~20 minutes, then rinse with pure water.  

◇ Fill all flow paths with 20% ethanol using *System Wash* or manual commands. Seal reagent bottles with parafilm, disconnect power, and cover the entire system to prevent dust accumulation.

 

● Long-Term Storage Procedures for Chromatography Systems in Cold Room Environments

 

◇ Perform complete exterior cleaning, with special attention to salt residues  

◇ Flush with 1M NaOH solution (50% Pump A + 50% Pump B) at 10% maximum system flow rate for 20 minutes, then immediately rinse with pure water until conductivity approaches 0  

◇ Flush with 75% ethanol solution (50% Pump A + 50% Pump B) at 10% maximum flow rate for 20 minutes, then rinse with pure water  

◇ Fill all system flow paths with 20% ethanol using System Wash or manual commands, and seal reagent bottles with parafilm  

◇ Maintain power during stepwise temperature increase of chromatography cabinet .

Gradually raise cabinet temperature to ambient (minimum 30 minutes, with dehumidification continuously operating).Open cabinet door to allow air exchange until temperature and humidity stabilize.Then power off and either:  

   - Remove equipment (if cabinet will continue cold operation)  

   - Or leave in powered-off cabinet  

Finally, cover entire system for dust protection

 

3.  Common Issues in Protein Purification Systems Root Cause Analysis and Solutions

① System overpressure:

1) Monitor pressure changes by disconnecting the system in sections, and identify system blockage points one by one, prioritizing components prone to blockage, such as the inline filter and backpressure valve. If the inline filter is clogged, ultrasonic cleaning can be performed. If cleaning is ineffective, the filter needs to be replaced.

2) If the backpressure valve is clogged, ultrasonic cleaning can be performed on the entire valve. If cleaning is ineffective, contact after-sales service for on-site disassembly, cleaning, or complete replacement.

3) If other components are detected to be clogged, disassembly, cleaning, or replacement can be performed, depending on the specific situation.

4) When using chromatography columns, carefully inspect the filter at the bottom of the column. System blockages can also occur due to damaged column screens and leaking packing.

② Flow Rate Pulsation/Inaccuracy:

1) Troubleshoot and address the plunger pump issue. First, check the inlet flow path for leaks. If leaks are detected, pump liquid through the drain valve to fill the pump chamber. Disconnect the connectors on both pump heads and observe the flow. If no liquid is coming out of one side, remove the upper and lower check valves and ultrasonically clean them. If none of the above steps resolve the issue, disassemble the pump head and inspect the internal plunger rod and cam.

2) Troubleshoot and address the damper issue. A leak or damage to the damper can cause abnormal pulses or flow rates. If leakage is detected on the table below the equipment, contact an engineer for an on-site inspection.

3) Troubleshoot and address any flow path leaks. If the flow rate is inaccurate, there may be a leak somewhere. Check for the leak along the flow path and address it promptly.

③ UV Fluctuation or Drift:

1) Prioritize investigating pump flow rate or pulse issues. Display the pressure curve to see if it fluctuates with the UV. If the fluctuation trend is consistent, the pump flow rate or pulse is the cause. Refer to the previous item.

2) UV flow cell issues: dirt, impurities, or microbubbles. Clean the flow cell according to the cleaning instructions for "Semi-Annually/UV Detector" above.

3) Temperature or Humidity Fluctuations and Abnormal Vibration: These can be caused by the equipment's environment. For example, if the system is housed in a chromatography cabinet and the cabinet's humidity and stability control are not functioning properly, resulting in large fluctuations, this can also cause abnormal UV fluctuations or drift. In this case, the cabinet should be inspected and the interference removed. Similarly, vibrations from other equipment surrounding the purification system, such as centrifuges, shakers, and the chromatography cabinet compressor, can also cause UV fluctuations. These should be investigated and, if necessary, the system relocated to avoid the source of vibration. 4) Power supply or static electricity: System power supply issues (such as unstable voltage or ground wire failure) can cause UV fluctuations. Check that the device's power supply is normal. The voltage should be between 220-240VAC, without surges, and the ground wire is functioning properly, with a neutral-to-ground voltage ≤ 2V.

4) Damage to the optical fiber or UV module: During routine equipment operation or relocation, impact or vibration from the protruding area of the UV flow cell can damage the optical fiber tip. If the problem persists after eliminating the two causes in 1.2, the optical fiber is likely damaged. Contact official after-sales personnel for an on-site inspection and treatment.

 

 

④ Inaccurate collection volume:

1) Prioritize investigating whether the pump flow rate is inaccurate or causing pulsation. See section ② for detailed solutions.

2) If the collector dripper is misaligned, causing liquid to splash, observe the collection process to see if this occurs. If so, readjust the dripper tube and calibrate the collector.

3) Other causes, such as switching the solenoid valve or the collector control board, require a repair request. If none of the above two issues are present, have the solenoid valve and control board inspected and replaced as necessary by a factory engineer.

 

The above information is for reference only and is intended to help purification professionals ensure their equipment remains up-to-date and maintains stable performance, thereby facilitating their experiments. Please be mindful of routine maintenance, and don't panic if problems arise. Most common problems are not caused by equipment malfunctions but can be resolved through careful investigation and consideration. Often, you can resolve the problem yourself without waiting for an engineer to arrive.