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Guard Cartridge System
SPE(Solid Phase Extraction)
Prep-LC & Bulk
Capillary LC
Amino Acid Analysis
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Chiral Analysis (̼ü)
Oligonucleotide Purification
Common Questions
Below are some common questions about the use and care of Axia packed columns.


Tips for improving column lifetime

The two main causes of preparative column failure are bed collapse and clogging
of the frit. Since Axia solves any problems with bed collapse as a source of

column failure,
the key to extending the lifetime of your Axia column is to reduce
frit clogging.

Some tips for improving column lifetime:
  • Filter or centrifuge sample before injection
  • Reduce DMSO injection solvent from 100% to 50%DMSO/50%Methanol
    (will help to minimize your sample from precipitation out of solution
    when introduced to the mobile phase)
  • Increase time of gradient at 100% organic (to improve column cleaning)
  • Use a SecurityGuard Prep system and/or in-line filter to capture mobile phase


How to gain more injections

Guard Columns

Guard columns are highly recommended for extended column lifetime.

Protect your Axia packed column and prolong its lifetime with SecurityGuard,
the advanced HPLC guard cartridge system.


  Get full protection with minimal impact on your chromatographic results.

Contaminants are retained by an inexpensive, 15 x 21.2mm ID, disposable cartridge



In-Line Frits

Phenomenex's PREP In-line Filter holder with replaceable filter element
(2µm stainless steel frit) will help protect against fouling by safely removing particulate
matter and insoluble material from the mobile phase and sample matrix.

The filter unit can be placed in the flow path before or after the column with little or
no effect on peak shape. This versatile filter can also protect check valves, injectors
and detectors. Pressure rated to 8,000 psi.

In-Line Frits

Watch the Backpressure

While Axia Packed columns are designed for high flow rates, you can extend your
lifetime by watching the backpressure and not exceeding 3500psi.


How to decrease analysis times

  • Investigate different column selectivities and pH to acheive improved results
  • If you have good resolution, consider decreasing column length for faster analysis time
  • Axia Packed columns are available in various stationary phases including C18, C8
    and Phenyl phases. To decrease hydrophobic retention from a C18, consider a C8
    column such as Luna C8(2).


How to scale-up

Adjusting a method to accommodate a change in load and scale requires changing
 multiple method parameters including flow rate and column ID.

Please note that with good resolution, far greater loading is possible with
the Phenomenex
high surface area medias.

Estimating Sample Load (mg) and Flow Rate (mL/min)

  Internal Diameter
Length (mm) 4.6mm 21.2mm 30mm 50mm
50mm 0.5-2 10-40 20-80 60-240
75mm 0.75-3 15-60 30-120 90-360
100mm 2-6 20-80 40-160 120-480
150mm 3-6 30-120 60-240 180-720
250mm 2.5-10 50-200 100-400 300-1200
Flow Rate (typical to high) (mL/min) (1-1.5) (20-30) (40-60) (120-180)

Axia-Packed columns available in 21.2mm ID, 30mm ID and 50mm, 75mm, 100mm length.
Other Prep dimensions shown available in PrepLC hardware.
"Email us for further information on Large Scale Prep and Bulk Material.


Scale-Up Calculations

Scaling a separation to meet prep demands requires the re-dimensioning of chromatographic
such as flow rate/ column ID/ sample load.

  When only the column ID is changing, the following will give you a general scaling factor (SF):
  SF= (d2/d1)2

  SF= Separation Factor
  d1= diameter of starting column
  d2= diameter you are scaling to


  When both ID and length are changing, the following will give you a general value:

  SF= (d2/d1)2*(L2/L1)

  SF= Separation Factor
  L1= length of starting column
  L2= length you are scaling to



How to increase loadability

  • Look for stationary phases with a high surface areas such as Synergi (475m2/g), Luna (400m2/g) and Gemini (375 m2/g)
  • For basic compounds, consider loading at high pH for increased sample load.


The high loadability and chemical inertness of Gemini make it ideal for preparative and
process scale applications.

With stability to pH 12, Gemini delivers long column lifetimes for high pH preparative
purification of basic compounds.

The high surface area of the Gemini phase allows for greater mass loading on
applications at both low and high pH.


Improve Resolution and Increase Loadability



How to maintain column reproducibility

Select a manufacturer with the capability to control the column to column variability.

The technology for Axia Packed columns- Hydraulic Piston compression- allows for
up to a 3-fold
improvement in column to column reproducibility.

With Axia- the piston compresses the bed and the pressure is never released.
The correct slurry amount and packing pressure are automated for reproducible
packing control.

In the example to the right, please see the improved %RSD for efficiency in
Synergi Hydro-RP columns
from the conventional slurry packing to Axia Packing.

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