Step 1: Normalize the spec (make them equivalent)
Before comparing price, confirm both quotes refer to the same effective product. Many “cheaper” offers are simply lower concentration, different grade, or different impurity limits.
Spec normalization checklist
- Exact identity: chemical/trade name, grade, and concentration (e.g., 30% vs 33% vs 37%).
- Active content: compare price per kg of actives (or per effective unit, see formula below).
- Impurities & limits: chloride, sulfate, metals, moisture, insolubles, color, odor—whatever matters for your process.
- Physical form: solution vs flakes vs powder, particle size distribution, bulk density, anti-caking additives.
- Stabilizers/additives: inhibitors, surfactants, defoamers, dyes/fragrance (sometimes unacceptable on-site).
Quick calculation: “price per effective unit”
Use this when concentration differs:
Effective unit price = (Quoted unit price) ÷ (Active fraction)
Example: 1.00 €/kg at 30% active → 1.00 ÷ 0.30 = 3.33 €/kg active
If the product is used at different dosages (e.g., 1% vs 2%), compare cost in use instead: unit price × typical dosage × consumption volume.
Step 2: Validate documentation (reduce legal + quality risk)
A quote is not “procurement-ready” until the supplier can support it with current, traceable documentation. The goal is simple: you should be able to verify what arrived at your gate.
Documents to request (minimum)
- SDS: latest revision date; matches the exact product name and supplier/manufacturer.
- COA (per batch/lot): includes the parameters you care about + pass/fail limits (not only “typical”).
- Traceability: batch/lot on label must match COA and shipping documents.
- Origin/manufacturer statement: when required by your QA/compliance process.
- Regulatory statements (as needed): REACH, food-contact, allergen/non-animal, heavy metals, VOC declarations, etc.
Red flags
- SDS is old, generic, or not matching the product name/grade you’re buying.
- COA is “typical values only” with no limits, no test method, or no batch reference.
- No clear manufacturer (trader-only paperwork) when your site requires manufacturer traceability.
- Missing statements for restricted substances or site rules (often discovered after delivery).
Step 3: Check compatibility & operational fit (avoid downtime)
Compatibility problems create hidden cost fast: corrosion, swelling seals, foaming, residue, odor carryover, or product instability. If the quote doesn’t state boundaries, assume there’s risk.
Operational fit checklist
- Materials in contact: metals, plastics, elastomers, coatings, hoses, pump seals.
- Operating window: temperature range, pH range, contact time, agitation/pressure.
- Process constraints: foam tolerance, rinse quality, wastewater limits, CIP return behavior.
- Storage & stability: shelf life, freeze/thaw sensitivity, separation, crystallization, venting requirements.
Procurement question that catches problems early
Ask suppliers: “What are the top 3 failure modes in real operations, and what controls prevent them?”
Good suppliers will mention things like dilution order, temperature limits, foam control, rinse steps, or incompatibilities.
Step 4: Align logistics (the offer must be deliverable)
Many quotes are not comparable because logistics are not equivalent. One might be EXW in drums, another DAP in IBCs, with different lead times, MOQs, or packaging linings.
Logistics comparison checklist
- Incoterms: EXW/FCA/FOB/CFR/CIF/DAP/DDP—ensure both offers use the same term (or add the missing costs).
- Packaging: drum/IBC/bulk, liner type, closures, UN packaging if hazardous.
- MOQ & order multiples: pallet quantity, full truck/container constraints, call-off capability.
- Lead time: standard lead time + variability risk (ask if it’s ex-stock or made-to-order).
- Shelf life & storage: receiving inspection timing, temperature constraints, “best before” impact.
Step 5: Calculate total cost (the decision layer)
Unit price is rarely the biggest driver. Compare the cost and risk of running the chemical in your operation.
Total cost drivers to include
- Cost in use: dosage/concentration, consumption per shift/week, rework frequency.
- Quality workload: incoming QC tests, nonconformance handling, quarantine time.
- Downtime risk: cleaning failures, corrosion, foam trips, residue issues, filter plugging.
- Waste & disposal: wastewater treatment impact, neutralization needs, sludge generation.
- Supply risk: lead time uncertainty, single-source dependence, documentation delays.
Common hidden gotchas (what “cheap” often means)
- Different assay/dilution assumptions: quote looks cheaper but actives are lower.
- Non-equivalent impurity limits: higher chlorides/metals cause corrosion or QC rejects.
- Packaging liner mismatch: wrong liner for corrosives/solvents = leakage or contamination risk.
- Missing temperature window: product crystallizes, separates, or degrades in winter/summer transport.
- No acceptance criteria on receipt: you can’t prove a batch is out of spec until it fails in process.
- Lead time not realistic: “2 weeks” offered but actually “2 weeks after production slot.”
- Non-comparable Incoterms: EXW vs DDP can dwarf unit price differences.
Decision summary (one-page template)
Create a one-page comparison and score each offer on five lines: (1) price per effective unit, (2) documentation completeness, (3) compatibility risk, (4) logistics/lead time risk, (5) operational KPI impact.
Want help structuring the decision?
Share the two offers (you can redact company names and prices if needed). We can help you normalize specs, highlight risks, and convert both quotes into a clean one-page comparison for internal approval.
Educational content only. Always follow your site EHS rules and supplier SDS guidance. Final selection should be validated with your process conditions, compliance requirements, and receiving/quality procedures.