Compare bulk surfactant quotations by dividing the cost to the same receiving point by the kilograms of agreed surfactant active matter in each delivery. First confirm what the active percentage measures, whether it is reported by mass on the supplied product, and which net weight governs the comparison. Solids may include non-surfactant material, while gross shipment weight includes packaging. Using either as the active-matter denominator can change the price ranking. This calculation supports commercial screening between technically comparable candidates; approval for use remains specific to the grade, formulation and receiving process.

Define What the Percentage Measures

A quotation stating “70% content” leaves the pricing basis unresolved.

Stepan’s surfactant selector guide distinguishes actives from solids and explains that solids can include inorganic salts and other substances. A solids percentage therefore cannot automatically serve as a surfactant-active percentage.

For aqueous sodium laureth sulfate, alkyl polyglucoside solutions and formulated blends, establish the definition for the exact commercial grade.

A blend requires particular care. One supplier may report total surfactant actives, another anionic actives, and another nonvolatile residue. Dividing price by these percentages creates different denominators. Keep those offers outside a common active-cost ranking until the reported quantities can be reconciled.

If an assay is reported on a dry basis, obtain the supported conversion to the supplied-product basis before calculating delivered active kilograms. The percentage printed on the certificate is not necessarily the fraction to multiply by the shipment’s net weight.

Make the Active Results Comparable

An active-matter result depends on the substances counted and the calculation used to report them.

The published abstract of ISO 2271:1989 states that the relative molecular mass of the anionic active matter must be known. It also excludes samples containing cationic surfactants. These limitations matter when interpreting mixtures; this is not a universal assay for every surfactant family. The public abstract establishes that scope rather than providing the complete analytical procedure.

Manufacturer data illustrate why the calculation basis deserves attention. Stepan’s STEOL CS-270 PLUS bulletin reports typical actives with a molecular-weight basis of 382. That basis belongs to the stated product data and should not become a default for every sodium laureth sulfate grade.

Before comparing percentages, confirm:

• Which components the result includes.
• Whether the result is a mass percentage on the supplied product or on a dry basis.
• The method and any molecular-weight or equivalent-weight basis.
• Whether the figure is typical data, a contractual specification or an actual batch result.

Keep these evidence types separate.

Typical concentration supports an indicative quotation comparison. A contractual minimum supports a minimum-content calculation: at a fixed delivered cost and net weight, it gives the highest calculated cost per kilogram of active within the agreed concentration range. It does not establish the actual batch concentration.

Actual assay can support batch-specific settlement only where the purchasing agreement defines the applicable result, sampling procedure, calculation and dispute process.

Calculate Cost per Kilogram of Active Matter

Once the bases match, calculate:

Active matter delivered, kg = net product weight, kg × active-matter mass fraction

Delivered cost per kg active = total cost to the agreed receiving point ÷ active matter delivered, kg

Enter 70% as 0.70.

Use the same cost boundary for every offer. Record the currency, quotation validity, receiving point and included charges. Apply consistent treatment to freight, insurance, nonrecoverable duties, destination charges, recoverable taxes and refundable packaging deposits.

A Hypothetical Quotation Comparison

The figures below are invented solely to demonstrate the calculation. They are neither market prices nor supplier quotations.

Assume technically comparable materials, the same agreed mass-based active definition and identical delivery-cost coverage.

Offer B has the lower price per kilogram of supplied product. Offer A has the lower calculated price per kilogram of active matter.

Delivering 14,000 kg of active matter through Offer B would require approximately 20,588 kg of supplied product. The cost of that larger shipment requires a new quotation because freight, packaging and order increments may change.

The calculation establishes a concentration-adjusted price ranking under the stated assumptions. It does not establish equal cleaning, foam or processing performance.

Keep Solids Separate From Active Matter

Suppose a hypothetical offer reports 70% solids and 68% active matter, both by mass on the supplied product. Use the supported 68% result for the active-matter calculation.

Do not identify the difference as a particular salt or impurity without compositional evidence. Different analytical procedures may also prevent the two results from forming a clean component mass balance.

Material outside the agreed active fraction can still influence the formulation. Its contribution belongs in technical evaluation; the commercial calculation should preserve the agreed definition of surfactant active matter.

Check Whether Concentration Changes Receiving Costs

At an equal active requirement, higher concentration reduces the calculated mass of supplied product. Whether this reduces the total purchasing cost depends partly on how the grade enters the receiving and preparation process.

Alcohol ethoxylates provide a specific example. Sasol’s MARLIPAL 24 technical handbook, section 4.2, pages 8–9 describes increasing water solubility with increasing ethoxylation within that series. It also describes intermediate-concentration paste or gel regions when these products are mixed with water.

Those findings connect grade and composition to an observable receiving problem: a dilution can pass through a highly viscous region even when the purchased material and intended final dilution are usable.

The procurement implication is conditional. If a concentration or grade change alters the dilution task, verify the actual addition sequence and mixing behavior before assigning an operational cost advantage. The handbook’s behavior cannot be transferred unchanged to another alcohol ethoxylate grade, an alkyl polyglucoside or a complete cleaner formulation.

ChemicalCell’s alcohol ethoxylate haze investigation addresses follow-up diagnosis when dilution produces haze or gel.

Agree What “Delivered Weight” Means

For packaged material, distinguish gross package weight, tare and net contents.

For bulk deliveries, specify whether the commercial quantity comes from dispatch weighing, receiving weighing or another agreed measurement. Record the point at which quantity is determined.

If quantity is measured by volume, convert it to mass using the applicable density and temperature basis before multiplying by a mass-based active fraction.

Keep delivered quantity separate from quantity transferred into the receiving tank. Residual material in containers or unloading equipment can affect usable yield. Include that difference only where representative recovery measurements support it; do not apply a universal loss allowance.

Use the same boundary across candidates. A comparison based on active matter dispatched and another based on active matter transferred into storage cannot share an unqualified “delivered active cost” heading.

Where handling costs or measured recovery losses are included, label the expanded calculation and identify the additional assumptions.

Resolve Conflicting Results Before Adjusting Settlement

If supplier and receiving assays disagree, first compare sample identity, reporting basis, method and sample preparation.

Where a shipment shows separation or a concentration gradient, a single grab sample may not represent the whole delivery. Document the observed condition and establish a representative sampling procedure consistent with the material’s handling requirements.

Apply commercial adjustments through the agreed quantity and assay rules. Conflicting results alone do not establish whether the cause lies in shipment composition, sampling, analysis or documentation.

Decide Which Offers Can Enter the Ranking

Request documents according to the unresolved decision.

The grade-specific specification establishes the contractual concentration range. The method reference explains what the percentage measures. The certificate of analysis connects a result to a batch. Weight records establish quantity, and the quotation establishes the cost boundary.

The safety data sheet supports handling and hazard assessment. It should not serve as the sole evidence for a precise commercial active-matter assay.

ChemicalCell’s Surfactant directory provides a starting point for browsing material families. Confirm the exact grade, concentration and analytical basis for each candidate offer.

Complete the Comparison Before Selecting the Lower Price

A defensible ranking requires a common measured quantity and a common commercial boundary. Concentration-adjusted cost then shows what each offer charges for the agreed active quantity.

For a proposed replacement, equal-active trials provide a controlled starting comparison. Approval remains tied to the intended formulation, preparation procedure and acceptance criteria.

Obtain one reconciled quotation sheet for each candidate, identifying the exact grade, active-matter definition and specification, assay basis, net-weight settlement point and total cost to the same destination. Rank the offers once those fields agree, with technically unqualified candidates clearly marked.