With the wide pH window, the Eternity platform gives users more flexibility to optimize selectivity and loading capacity compared to regular silica materials.

Optimizing resolution

Substances with ionizable groups will exhibit significantly different retention times depending on their degree of ionization. Hence, by changing the ph, selectivity between substances can be altered so that resolution is optimized for a given separation.

In many cases, pharmaceuticals are basic. They are ionized at low or neutral ph, resulting in low retention, poor loadability and broad peaks. Being able to run at high ph means compounds become more retained with narrower peaks, revealing higher chances for better resolution and loadability.

Running at high pH

Basic pharmaceuticals become neutral at high pH and exhibit significantly sharper analytical peaks and higher loadability. Higher loadability means higher productivity, leading to a much more economical purification process. With EternityXT, large- scale separations can be run for an extended time, even at levels as high as pH 12.

Choose selectivity by tuning pH

Separation on EternityXT C18 at different pH
  • Conditions
  • Column: Kromasil EternityXT-2.5-C18 4.6 × 50 mm
  • Mobile phase: acetonitrile / 20 mm sodium phosphate pH 2.1, 7.2 and 11.3
  • Gradient: 0-0.5 min: 10%, 5.5 min: 50% acetonitrile
  • Flow rate: 1.5 ml/min
  • Temperature: 25 °C
  • Detection: UV @ 254 nm
  • Substances: 1 = uracil
  •   2 = procaine,
  •   3 = fenuron,
  •   4 = 3-nitrobenzoic acid

Improved resolution at high pH

Chromatograms showing separation of anilines and illustrating the significant advantage of being able to use almost the entire pH range for developing a separation method. The low pH (pH = 2.5) chromatogram shows a non-favorable situation, with coelution of two pairs of peaks. However, at high pH (pH = 10.5), a chromatogram with well separated peaks can easily be obtained.
  • Conditions
  • Column: Kromasil EternityXT 10-C18, 4.6 × 250 mm
  • Mobile phase: acetonitrile / 10 mm potassium phosphate
  • Gradient: 0 min: 20%,
  •   2 min: 29.5%,
  •   16 min: 29.5%,
  •   26 min: 90% acetonitrile
  • Flow rate: 1 ml/min
  • Temperature: ambient
  • Detection: UV @ 254 nm
  • Substances: 1 = caffeine,
  •   2 = aniline,
  •   3 = 2-nitroaniline,
  •   4 = 2,4-dinitroaniline,
  •   5 = 2-etoxyaniline,
  •   6 = 3,5-dimethylaniline,
  •   7 = 3-ethylaniline,
  •   8 = N,N-diethylaniline,
  •   s.p. = solvent peak (acetone)
  • At low pH
  • pH: 2.5
  • At high pH
  • pH: 10.5

Stronger than ever

Kromasil EternityXT is based on the Kromasil 100 Å silica matrix, with exeptional mechanical stability as a resultof the almost perfect spherical shape, combined with a proprietary process to further strengthen the matrix. In EternityXT, the new organic/inorganic platform reinforces the structure to an even higher level.
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