HPLC Columns User Guide


SepaPrep™ HPLC Column User Guide


The following guidelines outline best practices for the proper installation, use, and maintenance of SepaPrep™ HPLC columns to ensure reliable performance and long column lifetime.


 


Column Installation


Proper column installation is essential to ensure optimal chromatographic performance and to maximize column lifetime.


Installation recommendations



  • • Upon receipt, verify that the column type and configuration match your application requirements.

  • • Remove the protective caps from both ends of the column before use and retain them for future storage or shipment.

  • • Ensure that the flow direction indicated by the arrow on the column corresponds to the direction of the HPLC mobile phase flow.

  • • Install the column using appropriate fittings, such as finger-tight PEEK fittings or stainless steel fittings, depending on operating pressure and application needs.

  • • Minimize system dead volume by using connection tubing with a small internal diameter. For analytical columns, tubing with an internal diameter of 0.25 mm or less is recommended.

  • • Keep tubing lengths between the injector, column, and detector as short as possible to reduce band broadening and maintain chromatographic efficiency.


 


Column Activation


Before first use, HPLC columns must be properly activated to ensure optimal performance and stable retention behavior.


Recommended activation



  • • Initial flow rate: 0.2 mL/min

  • • Reversed-phase and ion-exchange columns should be flushed with 20 - 30 column volumes of methanol or acetonitrile.

  • • Normal-phase, HILIC, and bare silica columns should be flushed with 20 - 30 column volumes of isopropanol.


After activation, gradually transition to the intended mobile phase before beginning runs.


 


Sample Handling


Proper sample preparation is essential to maintain column performance and extend column lifetime.


Recommendations



  • • All samples and mobile phases should be filtered using 0.20 to 0.45 μm filters prior to injection.

  • • To obtain symmetrical peak shapes and stable baselines, it is recommended to dissolve samples in the initial mobile phase composition.

  • • Avoid injecting samples dissolved in strong solvents that differ significantly from the starting mobile phase, as this may cause peak distortion or retention shifts.


 


Mobile Phases and pH Considerations



  • • If non-volatile buffers have been used, ensure complete removal before switching to incompatible solvents.

  • • Elevated pH can gradually dissolve silica, leading to efficiency loss and retention shifts.

  • • To extend lifetime, operate SepaPrep™ columns within their specified pH ranges.

  • • Above pH 9, phosphate buffers. Organic amines or ammonia are generally preferred, especially for LC-MS methods.


Always refer to the recommended pH range of the specific SepaPrep™ stationary phase in use.


 


Pressure Limits


SepaPrep™ HPLC columns are designed to tolerate high operating pressures, but prolonged operation at extreme pressures should be avoided.



  • • Maximum pressure tolerance: up to 400 bar

  • • Recommended normal operating pressure: below 200 bar


 


Temperature Limits


The standard maximum operating temperature is 60°C. However, continuous operation above 45°C may reduce column lifetime, particularly under elevated pH conditions. For silica-based bonded phases, an operating temperature range of 25 to 35°C is recommended to ensure optimal column longevity.


 


Storage Conditions


For long-term storage, avoid leaving highly aqueous or high-salt mobile phases inside the column. Residual aqueous buffers should be removed by flushing the column with 20 - 30 column volumes of a salt-free eluent, followed by 20 - 30 column volumes of an organic solvent such as methanol or acetonitrile.


After flushing, securely install the end fittings on both sides of the column to prevent drying. The table below summarizes the recommended storage solvents according to column type.

































Chemistry TypeStationary PhaseRecommended Storage Solvent
Reversed-PhaseC18, C8, Amino (NH₂)*, Cyano (CN)*, Phenyl, etc.Methanol
Normal PhaseSilica, Cyano (CN)*Hexane or Isococtane:Ethanol
HILICAmino (NH₂)*Acetonitrile, Hexane, Acetonitrile:Water or Butyl chloride:Methanol
HILICHILICMethanol


* Phases marked with an asterisk should be flushed with a fully miscible solvent, such as isopropanol, before first use if an aqueous mobile phase is applied.


 


Use of Guard Columns


For complex sample matrices, direct injection onto the column should be avoided whenever possible.



  • • The use of a guard column is strongly recommended to protect the column from particulate contamination and strongly retained impurities.

  • • Alternatively, sample pre-treatment techniques such as solid-phase extraction (SPE) may be used to remove matrix interferences.


Proper use of guard columns significantly extends column lifetime and maintains chromatographic performance.


 


Column Regeneration


A gradual increase in backpressure over time is normal. A sudden increase usually indicates inlet contamination or partial blockage. Cleaning or regeneration may help restore column performance.


The table below provides general guidelines for column cleaning and regeneration, depending on column chemistry.




























Chemistry TypeCleaning ProcedureRegeneration Procedure

Reversed-Phase


(C18, C8, Amino (NH₂), Cyano (CN), Phenyl, etc.)




  • • Set the flow rate to 20 - 50 % of the normal operating flow rate.

  • • Flush the column with 2 - 3 column volumes of appropriate solvents, starting with a water/methanol (50/50) mixture to remove buffers and polar contaminants, followed by 100 % methanol, and finally the mobile phase used during the separation.




  • • Reverse the flow direction (backflush) and reduce the flow rate to a very low value.

  • • Regenerate the column by sequentially flushing with at least 10 - 15 column volumes of common solvents (organic solvents, progressing from aqueous/organic mixtures such as water/methanol 90/10 or 70/30 to amino or Cyano phases) to pure organic solvents such as methanol, acetonitrile, or isopropanol.

  • • If required, non-polar solvents including dichloromethane or hexane may be used before returning to the mobile phase applied during the separation.


Note: If dichloromethane or hexane is used, isopropanol must be used as a transition solvent before returning to reversed-phase mobile conditions.



Normal Phase


(Silica, Amino (NH₂), Cyano (CN), etc.)




  • • Set the flow rate to 20 - 50 % of the normal operating flow rate.

  • • Clean the column by flushing with 2 - 3 column volumes of isopropanol, followed by hexane, and then re-equilibrate with the mobile phase used during the separation.


Note: Water should not be used with normal-phase columns.




  • • Reverse the flow direction (backflush) and reduce the flow rate to a very low value.

  • • Regenerate the column by sequentially flushing with at least 10 - 15 column volumes of a polar organic solvent compatible with the stationary phase (such as isopropanol or methanol), followed by hexane, and then re-equilibrate with the normal-phase mobile phase used during the separation.


Note: Alternative compatible solvents may be used at the user's discretion.


HILIC

  • • Set the flow rate to 20 - 50 % of the normal operating flow rate.

  • • Flush the column with 2 - 3 column volumes of acetonitrile/water (80/20) to remove polar contaminants, followed by 100 % acetonitrile, then re-equilibrate with the initial HILIC mobile phase used during the separation.




  • • Maintain a low flow rate.

  • • Regenerate the column by flushing 2 - 3 column volumes of acetonitrile/water mixtures of increasing water content, followed by 100 % acetonitrile, then re-equilibrate with the initial HILIC mobile phase used during the separation.


Note: Ensure full solvent miscibility and avoid abrupt transitions between high-aqueous and high-organic conditions.




 


Important Notes



  • • Always ensure solvent miscibility before switching solvents to avoid phase separation or column damage.

  • • When using dichloromethane or hexane, isopropanol must be used as a transition solvent before returning to reversed-phase mobile conditions.

  • • For HILIC columns, avoid abrupt changes between high-organic and high-aqueous mobile phases. Gradual solvent transitions are recommended to maintain stable retention and column performance.

  • • Do not exceed the maximum pressure rating of the column.

  • • Maintain reduced flow rates during cleaning and regeneration procedures to minimize mechanical stress on the packed bed.

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