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The Kromasil® Classic 60 Å family of products is the choice for small, organic molecules when a large, accessible surface area is key for separating peaks in analysis. It also has the added properties of loadability and capacity required for purification.
Derivatized stationary phase materials based on Kromasil® 60 Å silica are developed and manufactured to give high reproducibility and chemical stability. Scientists can benefit from this range of products for applications within normal phase, reversed phase, HILIC and SFC.
Exploit selectivity differences with Kromasil
With the wide range of derivatizations available for Kromasil® particles, users can test sets of columns to determine which is best for a given sample. The following three chromatograms illustrate the differences in selectivity and resolution highlighted by the exposure of the same mixture of compounds to Kromasil® Diol, Silica and Cyano columns.
There is an increased interest within the pharmaceutical industry for polar compounds. Traditionally, it has been a challenge to separate polar compounds such as organic acids, nucleobases, and water soluble vitamins on standard reversed phase columns such as C18. For this reason, within Kromasil® Classic 60 Å, Kromasil® HILIC-D has been developed for optimal selectivity of polar compounds. This phase is also 100% MS compatible, which works well for laboratories using LC/MS technologies.
- Conditions
- Columns: Kromasil 60-5-CN 4.6 × 250 mm
- Kromasil 60-5-SIL 4.6 × 250 mm
- Kromasil 60-5-Diol 4.6 × 250 mm
- Mobile phase: heptane / 2-propanol (85/15)
- Flow rate: 2 ml/min
- Temperature: 20 °C
- Detection: UV @ 224 nm
- Sample: 1 = tri-tert-butylbenzene, 2 = 2-ethoxyaniline, 3 = aniline, 4 = catechol, 5 = 2,4-dinitroaniline, 6 = hydroquinone, 7 = 4-nitroaniline
Kromasil® silica is also recognized for its loading capacity and its benefits in the purification of compounds. The chromatogram below shows the loading of Oxirane onto a 4.6 mm ID column, traditionally regarded as a column for analysis. However, this column format allows the user to perform these types of experiments to verify the loading capability of the stationary phase and then seamlessly scale up for the final purification needs.
Chromatographic results with C18 and HILIC-D. Retention times vary due to the interactions between the substance structures and the differences in principles of reversed-phase and hydrophilic interaction chromatography. Further, with this particular mixture, selectivity reversal is achieved.
Kromasil® CN (cyano) was used for the large-scale separation of a diastereomeric oxirane derivative, where the chromatograms show the scale-up experiments in analytical scale. Even at a loading corresponding to 172 mg loading in analytical scale, i.e. 86 mg crude/g of packing, 98–99% pure diastereomers could be obtained in the two collected fractions. Recovery was close to 100%.