Inulin Analysis - COSMOSIL Application Note
Due to the lack of retention on ODS columns, oligosaccharides have typically been analyzed on specialty sugar columns. We have successfully analyzed inulins using COSMOSIL Sugar-D, a specialty column for saccharide analysis, and PBr, a unique reversed-phase column for polar and non-polar analytes.
About Inulin
Inulin (G-Fn) is a polysaccharide composed of a glucose unit (G) bonded to multiple fructose units (F). It is an indigestible, water-soluble dietary fiber, abundant in the roots of chicory and tubers of Jerusalem artichokes.
Recently, oolong tea with inulin has been released as a functional food in Japan on the basis that inulins feed intestinal bacteria by forming short-chain fatty acids and facilitate the peristaltic movement in the bowels. In the literature as well, there are references to inulin's effect on bowel movements. (1),(2)
Sample preparation
Inulin standard- Weigh inulin standard.
- Dissolve in Milli-Q water to a concentration of 10 mg/mL.
- Load 400 µL of oolong tea with inulin into a Cosmospin Filter H (pore size 0.45 µm) and centrifuge.
- Use filtrate as sample.
Analysis using Sugar-D
- 1-Kestose
- Nystose
Separation of inulin (G-Fn) was accomplished using Sugar-D, a specialty column for sugars. Based on the retention time of the short-chain 1-kestose (G-F-F) and nystose (G-F-F-F), it is thought that the separation is based on sugar chain length.
| Conditions | |
|---|---|
| Column | COSMOSIL Sugar-D, 4.6mmI.D.-250mm |
| Mobile phase | MeCN / H2O = 60 / 40 |
| Temperature | 30°C |
| Flow rate | 1.0 mL/min |
| Detection | RI (cell temp. 40°C) |
| Sample | Inulin standard (10 mg/mL) |
| Inj. vol. | 10 µL |
Reversed-phase analysis
- 1-Kestose
- Nystose
Inulins are not retained on the ODS column 5C18-PAQ. However, PBr can utilize dispersion force interaction to separate inulin by chain length.
| Conditions | |
|---|---|
| Column | COSMOSIL ***, 4.6mmI.D.-250mm |
| Mobile phase | MeOH / H2O = 15 / 85 |
| Temperature | 30°C |
| Flow rate | 1.0 mL/min |
| Detection | RI (cell temp. 40°C) |
| Sample | Inulin standard (10 mg/mL) |
| Inj. vol. | 10 µL |
Oolong tea with inulin: reversed-phase analysis
Upon analyzing oolong tea with inulin (inulin conc. 7.3 g / 500 mL), a similar chromatogram to the standard was obtained.
| Conditions | |
|---|---|
| Column | COSMOSIL PBr, 4.6mmI.D.-250mm |
| Mobile phase | MeOH / H2O = 15 / 85 |
| Temperature | 30°C |
| Flow rate | 1.0 mL/min |
| Detection | RI (cell temp. 40°C) |
| Sample | Oolong tea with inulin (inulin conc. 14.6 mg/mL) |
| Inj. vol. | 10 µL |
