How to Compare the Specifications of Six Common HMO Types

Side-by-Side Specification Review

Six HMO Specifications at a Glance

When you place the six specification sheets side by side, the assay values are the most visible difference. They range from at least 80.0% for LNT to at least 94.0% for 2'-FL, but those figures do not use one universal comparison standard. The table keeps each assay beside its calculation basis, water limit, lactose limit, and related-carbohydrate profile.

Do not sort these products by assay percentage and treat the result as a quality ranking. For example, the LNT specification allows more types and a higher combined amount of related carbohydrates than the 2'-FL specification because the two products and processes differ. Compare a batch with the specification for that HMO, not with the assay target of another HMO.

When the Percentages Look Comparable

Why the Percentage Alone Is Not Enough

If your shortlist shows a minimum assay of 94.0% for 2'-FL, 92.0% for LNnT, and 80.0% for LNT, it is tempting to rank them from highest to lowest. That comparison is misleading. Each percentage refers to a different molecule and may use a different calculation basis. Check whether the result uses a water-free, dry-matter, or as-is basis before comparing it with another number.

What Water-Free and Dry-Matter Basis Mean

A water-free or dry-matter result expresses the target HMO as a percentage of the non-water part of the sample. The laboratory measures water separately, then calculates the HMO percentage without counting that water in the total. The terms often describe the same practical idea, but the controlled method and formula still need confirmation.

An as-is result uses the powder in its received condition, including its water. For that reason, a water-free assay should not be compared directly with an as-is assay. Our current 6'-SL specification states the target assay but does not use the same water-free label shown on several other sheets, so the controlled specification and test method should confirm the basis before a numerical comparison.

When the Impurity Rows Do Not Match

How Related Carbohydrates Differ

After checking the assay, purchasing teams often move to the impurity section and expect the same rows on every specification. They will not find them. Each HMO has its own relevant starting sugars, structural isomers, and related oligosaccharides. A clear specification names these compounds instead of hiding them under one generic "impurities" line.

Fucosylated HMOs

The 2'-FL specification limits D-lactose and difucosyllactose. The 3-FL specification limits D-lactose, free L-fucose, and the combined amount of D-galactose and D-glucose. These lists differ because 2'-FL and 3-FL use different structures and product-specific purification controls.

Neutral Core HMOs

The LNnT specification includes limits for its fructose isomer, Lacto-N-triose II, and linear Lacto-N-neohexaose. The LNT specification includes Lacto-N-triose II, larger related oligosaccharides, D-lactose, free D-galactose and D-glucose, and other carbohydrates. Nutrition companies should review the main LNnT or LNT assay together with the complete carbohydrate profile.

Sialylated HMO Sodium Salts

The 3'-SL Sodium Salt specification and 6'-SL Sodium Salt specification include sialyllactulose and N-acetylneuraminic acid limits. N-acetylneuraminic acid is the form of sialic acid used to build these HMOs. A formula team should also confirm the sodium limit and unit on the current controlled document before calculating the sodium contribution to the finished product.

Where Direct Comparison Is Possible

Five Release Controls Shared Across All Six HMOs

Not every row differs by product. Our six current specifications share the five limits below, so a quality team can compare this baseline directly before reviewing the extra tests required for a particular HMO or finished-product application.

CFU means colony-forming units, a laboratory estimate of viable microorganisms. EU in the endotoxin result means endotoxin units, not European Union. Endotoxins are components associated with certain bacterial cell walls, so fermentation-derived ingredients include a defined endotoxin limit.

Several specifications add further organisms or residue tests, such as Cronobacter, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, exogenous DNA, or viable production-cell residues. The additional panel should match the HMO, production process, finished-product category, and consumer group.

Before Comparing Any Result

Product Identity Still Comes First

First confirm that every document refers to the intended HMO. 2'-FL and 3-FL share a molecular formula and mass, as do LNnT and LNT, but their sugar units connect at different positions. The full product name, CAS number, and laboratory identity method separate each ingredient.

A nutrition company should match the specification, sample label, COA, safety record, and purchase order to the same full identity. An abbreviation such as "SL" or "FL" is not precise enough for release or regulatory review.

During Supplier Qualification

Specification, COA, and Regulatory Status Serve Different Purposes

These records often arrive together during supplier qualification, which makes them easy to treat as one document package. They answer different questions: the specification defines acceptance limits, the COA reports one lot, and the regulatory record addresses where and how the ingredient may be used. One cannot replace another.

In the United States, an ingredient review covers identity, specifications, and limits on the conditions of use; see the FDA guide to determining food-ingredient status. In the EU, a novel food application must include scientific information for the specific novel food under review; see the EFSA novel food application procedure. Links reviewed July 14, 2026.

Use our HMO use-level and regulatory guide for product-specific U.S. FDA and EU references. Keep that market review separate from the technical comparison in this article.

After You Receive the Documents

How Nutrition Companies Can Review an HMO Specification

When quotations, samples, and documents arrive from more than one potential supplier, reviewing them in a random order makes discrepancies difficult to trace. Start with identity, move to the specification and batch evidence, and finish with a trial in the actual formulation.

1. Confirm Product Identity

   Use the full HMO name, abbreviation, CAS number, and molecular form. For 3'-SL and 6'-SL, confirm that the document covers the sodium salt.

2. Confirm the Assay Basis

   Check whether the assay uses a water-free, dry-matter, or as-is calculation. Do not compare percentages until the calculation basis is clear.

3. Review the Carbohydrate Profile

   Compare the target HMO result with the product-specific related carbohydrates. Each HMO needs a different profile.

4. Review Chemical and Residual Limits

   Check water, residual protein, endotoxins, heavy metals, and any process-specific residue tests required for the project.

5. Review Microbiological Limits

   Match the microbial panel with the finished-product category, consumer age group, manufacturing process, and destination-market requirements.

6. Check One Batch in Detail

   Compare the controlled specification with the sample COA, then verify the method, unit, lot number, and specification revision.

7. Complete the Formulation Trial

   Run the HMO in the real formulation and process. Confirm solubility, taste, color, heat exposure, pH, moisture, and shelf-life conditions.