Resolving Maltrin® Excipient Interference in Acidic SEC Sugar Analysis (Shodex NH2P & VG-50 HILIC Alternatives)

Record: 682

Category: Column Selection
Product: NH2P-50 4E or VG-50 4E
Sample: Maltrin

Question

A customer at Patheon uses a Transgenomic ICSep ION-300 (300 × 7.8 mm) column with 0.015 M H₂SO₄, 0.4 mL/min, 40 °C, and RI detection to analyze six low–molecular-weight saccharide compounds. Their formulation contains Maltrin® (maltodextrin) as an excipient, which co-elutes with the six target peaks due to similar oligosaccharide chain lengths (DP 3–6).

Retention times of the six compounds range from 9.8 to 14.6 minutes, overlapping the Maltrin peak. The customer wants a Shodex column that will make the Maltrin excipient elute quickly at the beginning so it does not interfere. Is such a column available?

Answer

The ICSep ION-300 is a sulfonated PS-DVB resin in the H⁺ form, operating in ion-exclusion + low-resolution SEC under acidic aqueous conditions. Shodex SUGAR SH-series columns (SH1011 / SH1821) are the closest equivalents, sharing the same separation mechanism. However, changing from ION-300 to SH1011 will not eliminate Maltrin interference because Maltrin and the analytes have very similar degrees of polymerization (DP 3–6) and therefore the same hydrodynamic volumes under acidic SEC.

To separate the Maltrin excipient from the analytes, the customer must change the separation mode, not the SEC column. The recommended solution is to switch to amino-based HILIC, using either:

• Asahipak NH2P-50 4E (polymer-based amino HILIC)
• HILICpak VG-50 4E (polymer-based amino HILIC for reducing sugars)

HILIC separates saccharides by hydrophilicity, linkage type, branching, anomeric configuration, and slight DP differences, rather than purely by size. This mechanism change typically causes Maltrin® (a broad DP mixture) to elute as a separate, early broad band, while discrete tri-, tetra-, penta-, and hexasaccharides resolve later with good peak shape and spacing.

Because the customer uses RI detection, they should be aware that ACN-based HILIC mobile phases generate higher baseline noise than purely aqueous SEC. However, RI sensitivity on NH2P-50 4E and VG-50 4E is generally sufficient for typical saccharide concentrations.

To finalize the recommendation and column choice, it would be helpful to know the specific Maltrin grade or DE value, and a representative chromatogram from the current acidic SEC method.

Recommended Applications:

• Isomaltooligosaccharides (NH2P-50 4E)
• Isomaltooligosaccharides (VG-50 4E)

These show the improved HILIC selectivity required to separate DP 2–7 saccharides and demonstrate how HILIC resolves species that co-elute in acidic SEC.

Additional Comments

The six unknown saccharide compounds originally reported by the customer fall within the DP 2–6 oligosaccharide range, which explains why they co-elute with Maltrin® (maltodextrin) on acidic SEC columns. Based on their retention times and molecular-weight behavior on the Transgenomic ICSep ION-300, the customer described:

• Compound 1 (RT 9.811 min): Elutes in the same region as maltopentaose–maltotetraose, corresponding to DP 4–6 oligosaccharides.
• Compound 2 (RT 10.438 min): Falls between maltopentaose and 2′-O-fucosyl-lactose, also consistent with DP 4–6 species.
• Compound 3 (RT 11.101 min): Slightly higher retention than Compound 2, suggesting DP 3–5 saccharides.
• Compound 4 (RT 12.102 min): Matches the molecular-weight region of 2′-O-fucosyl-lactose and resolves in the trisaccharide range. SEC typically shows clear separation between trisaccharides, tetrasaccharides, and disaccharides in this region.
• Compound 5 (RT 12.638 min): Has a retention time similar to lactose, but its position excludes monosaccharides (which elute later). The retention behavior suggests a structural isomer, reflecting a different galactose–glucose linkage (β-1→2, β-1→3, or β-1→6).
• Compound 6 (RT 14.562 min): Also aligns with lactose-level molecular weight, indicating another lactose isomer with alternate glycosidic linkage.

These detailed saccharide characteristics reinforce why acidic size-exclusion chromatography cannot separate the Maltrin® excipient from the six analytes:
all species share nearly identical hydrodynamic volumes.

Switching to amino-based HILIC (NH2P-50 4E or VG-50 4E) enables separation based on:

• hydrophilicity
• branching pattern
• linkage position
• anomeric configuration
• DP differences (especially DP 2–7)

—making it the appropriate mechanism for resolving individual saccharides from the Maltrin background.

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