Welch products introduction

Ultisil General Series

Ultisil Series HPLC Columns are based on ultra-pure ( purity > 99.999% ) spherical and totally porous silica, unique bonding chemistry and proprietary surface modification techniques, producing excellent peak shape, column efficiency and exceptional lot-to-lot reproducibility. Ultisil column is the best choice for method development, owing to complete bonding chemistries and stable performance.

Features

  • Ultra-pure spherical porous silica, purity > 99.999%
  • High efficiency: theoretical plate > 80000/m
  • Excellent peak symmetry: tailing factor=0.95~1.05
  • Exceptional lot-to-lot reproducibility

SEM Pictures of Ultisil Particles


Trace Amount Metal Contents Test

A useful chromatographic test of trace amount of metal contents in the column is to compare the peak symmetry of one pair of positional isomers, 4,4’-dipyridyl and 2,2’-dipyridyl, and a neutral chelating reagent, 1,2-dihydroxylnaphthalene. 4,4’-dipyridyl, which cannot form chelating complex with metal, is used as a reference. 2,2’-dipyridyl and 1,2-dihydroxylnaphthalene, which are chelating reagents, are sensitive to trace amount metal in silica. When a C18 column based on type A silica or other so-called type B silica with higher metal content is used, the peaks of 2,2’-dipyridyl and 1,2-dihydroxylnaphthalene would tail or even totally disappear.
Ultisil XB-C18 provides good peak shapes in the separation of these three compounds under pH 7.6, which indicates Ultisil silica contains hardly any metals.

Separation of Basic Compounds Antidepressant at pH 7.0

Comparison of Peak Shape between Batch to Batch

Capacity Factor(K’) of Batch to Batch Reproducibility