Why Corrosive Chemical Quotes Rarely Compare on First Pass
If you have ever sent a short email asking three Chinese suppliers for a price on "sulfuric acid, 20 tonnes, best price," you already know the problem. One bid comes back for 98% acid in drums, another for 50% acid in an IBC, and the third for 70% acid in an ISO tank, each on a different Incoterm and a different port. The headline numbers look wildly different, but none of them are actually comparable, because they describe different products, different active content, different packaging, and different risk transfer points.
The fix is not negotiation skill. It is RFQ discipline. A request for quotation for bulk corrosive chemicals has to pin down a specific set of fields on every line item so that returned bids differ only on the variables you actually want to compare: price, lead time, and supplier reliability. This guide walks sourcing managers, plant engineers, and QA teams through those fields, using sulfuric acid, hydrochloric acid, and caustic soda as worked examples, and then shows how to use public trade statistics as a sanity check rather than a target price.
The Core Problem: Shipped Concentration vs 100% Active Basis
Corrosive commodities are almost always sold as aqueous solutions at several standard strengths. Sulfuric acid (H₂SO₄, molar mass 98.08 g/mol) commonly ships at 50%, 70%, or 98% w/w. Hydrochloric acid (HCl, 36.46 g/mol) ships at roughly 25%, 31%, or 36 to 38%. Caustic soda (sodium hydroxide, NaOH, 40.00 g/mol) trades as solid or flake at 96% or 99% industrial grade, and in higher purities for food, reagent, and electronic use.
The single most important thing an RFQ must demand is two numbers on every line: the exact shipped concentration, and a required 100% active-basis equivalent. The active basis is what lets you compare freight and price per active tonne. Consider two sulfuric acid quotes. A tonne of 98% acid contains 980 kg of actual H₂SO₄; a tonne of 50% acid contains 500 kg. If you compare the two on gross delivered weight, you are paying to ship water and calling it a bargain. Normalizing every bid to cost-per-active-tonne, and to freight-per-active-tonne, removes that illusion instantly.
So build the RFQ template with a mandatory conversion field. Ask each supplier to state shipped strength, then compute and declare the active tonnes in the shipment. If they quote 25 tonnes of 31% HCl, the active HCl is 7.75 tonnes, and your landed-cost math should run on that figure. This one requirement eliminates most of the "confusing mix" problem before any other field is discussed.
Field-by-Field: What Every RFQ Line Item Must Specify
Grade and the Application It Must Serve
Concentration is not grade. Grade speaks to impurity ceilings and intended use. Require the supplier to confirm the explicit grade and tie it to your application. Industrial caustic soda at 96% or 99% is fine for pulp, textiles, and effluent neutralization. Food grade must meet at least 98% assay with controlled heavy-metal limits. ACS reagent grade is specified at a minimum around 97% with tight impurity tolerances for laboratory work. Electronic or high-purity caustic soda is held to extremely low metallic contamination, often specified at 99.99% or better, for semiconductor and battery applications. Stating only "caustic soda 99%" invites a bid built to the cheapest interpretation.
COA Assay and Impurity Parameters per Grade
For each line, demand the certificate of analysis parameters you will actually test against on receipt. For sulfuric acid, that typically means assay (% H₂SO₄), iron, chloride, and residue on ignition, plus color and clarity for cleaner grades. For hydrochloric acid, specify assay, free chlorine, iron, sulfate, and heavy metals. For caustic soda, specify NaOH assay, sodium carbonate (Na₂CO₃), sodium chloride (NaCl), iron, and, for high-purity grades, individual metallic trace limits. Listing these parameters in the RFQ forces every supplier to quote a product that can pass your incoming inspection, not a generic datasheet.
UN Number and Dangerous-Goods Classification
These are regulated corrosives, and the UN number has to appear on the line item because it drives packaging, documentation, and freight surcharges. Sulfuric acid is UN1830, hydrochloric acid is UN1789, and caustic soda solution is UN1824 (solid caustic soda is shipped under a separate UN entry, so confirm the form). All fall under Class 8, corrosive substances. Requiring the UN number up front means the supplier quotes with dangerous-goods handling already priced in, rather than adding it as a surprise after the purchase order.
UN-Approved Packaging Format
Packaging materially changes price, drawdown behavior, and site handling, so specify it. The common choices for these products are UN-rated HDPE closed-head drums for smaller or multi-grade orders, composite IBCs with an HDPE inner receptacle for intermediate volumes, and the ISO tank container T11 for full bulk liquid loads. A T11 portable tank is the standard for bulk corrosive liquids and gives the lowest packaging cost per active tonne, but only if your site can receive, unload, and return or stage the tank. If you ask one supplier for drums and let another quote a tank, you are again comparing different cost structures. Pick the format, or ask each supplier to quote the same two formats side by side.
Order Quantity and Drawdown Rate
State the order quantity and your drawdown rate, meaning how fast you consume the material. A plant burning two tonnes of active acid a week has different packaging and delivery-frequency needs than one drawing a full tank monthly. Drawdown also affects shelf life and container return logistics, especially for IBCs and ISO tanks. Giving suppliers your consumption profile lets them propose a sensible lot size instead of guessing.
Labeling and Documentation for Sea Freight
For ocean shipment of Class 8 goods, the RFQ should list the documentation you expect: a compliant safety data sheet, the dangerous-goods declaration, correct GHS and transport labeling and marine pollutant marking where applicable, the COA per batch, and the packing list referencing UN packaging codes. Spelling this out avoids held containers and demurrage caused by missing or inconsistent paperwork.
Incoterm and Named Port
A price without an Incoterm and a named place is not a price. Define a single Incoterm and a named port so that every landed-cost assumption lines up. If you want FOB Shanghai, say FOB Shanghai; if you want CIF Rotterdam, say so. Mixing an EXW quote with a CIF quote and a DAP quote guarantees non-comparable totals because each shifts freight, insurance, and risk transfer to a different party. Lock the term, lock the port, and let suppliers compete inside those boundaries.
Lead Time and Dual Sourcing
Require a committed lead time from purchase order to vessel loading, and state any dual-sourcing requirement. Corrosive-chemical supply can be disrupted by plant turnarounds, port congestion, and regulatory holds, so many buyers qualify at least two suppliers per product and split volume. Make that expectation explicit so bidders know they may receive partial allocation and price accordingly.
Acceptance and Rejection Criteria
Close the loop with acceptance and rejection criteria tied to receiving inspection. State that each lot will be sampled and titrated on arrival, that assay must fall within a defined tolerance of the COA, and that out-of-spec material is subject to rejection, replacement, or price adjustment. A titration cross-check at receiving is the practical defense against concentration drift between the COA and the delivered product, and naming it in the RFQ sets the quality expectation before the first shipment moves.
Worked Examples by Product
For sulfuric acid, a clean RFQ line reads: 98% w/w H₂SO₄, industrial grade, UN1830 Class 8, COA to include assay, iron, and chloride, packaged in ISO tank container T11, 24 active tonnes per shipment, CIF named port, four-week lead time, titration on receipt within plus or minus 0.5% of assay. When you brief a prospective sulfuric acid supplier with that line, every return bid describes the same product and can be ranked on price-per-active-tonne and lead time alone.
For hydrochloric acid, specify shipped strength (for example 31% or 36 to 38%), the active-basis tonnes, UN1789 Class 8, impurity ceilings for free chlorine and iron, and whether you need composite IBCs with an HDPE inner receptacle or a bulk tank. A buyer sending that structured line to a hydrochloric acid supplier avoids the classic trap of comparing a 31% drum price against a 36% tank price as if they were the same deal.
For caustic soda, separate the grade question cleanly: industrial 99% flake for neutralization is a different RFQ line from electronic-grade high-purity material at 99.99% for sensitive processes, with correspondingly different COA parameters and packaging. When you issue the RFQ to a caustic soda supplier, state the grade, the application, and the metallic trace limits so the quote matches the duty the material must perform.
Using Public Trade Statistics as a Sanity Check, Not a Target Price
Buyers often want an outside reference to judge whether a quote is in a reasonable zone. Public trade data can help, but only as a directional check. According to UN Comtrade, China's 2025 imports of sulfuric acid (HS 280700) totaled 126,204,652 kg valued at USD 15,478,592, aqueous sodium hydroxide (HS 281512) totaled 445,923.085 kg at USD 3,072,759, and anhydrous ammonia (HS 281410, a related upstream chemical) totaled 348,510,536 kg at USD 133,039,758.
These figures are useful for two things. First, liquidity: the very large sulfuric acid and ammonia volumes signal deep, active flows, whereas the far smaller aqueous caustic soda import volume suggests thinner cross-border movement in that specific aqueous category. Second, directional grade-mix: an aggregate value divided by aggregate weight blends every concentration, grade, and packaging type in the data, so any implied unit figure is an average of unlike things, not a market price for your specific 98% acid or your 99.99% caustic.
That is exactly why these numbers must never be folded into an RFQ as a firm target price. If you tell a supplier "the Comtrade average says your price is too high," you are comparing your single, tightly specified grade against a statistical blend. Use the data to confirm that a product category is liquid and that your expected order size is plausible against national flows, then let your specification-driven RFQ, normalized to active tonnes and a fixed Incoterm, do the actual price comparison.
Putting It Together: A Repeatable RFQ Discipline
The payoff of this structure is that quote evaluation stays grounded in specifications. Every bid you receive should state shipped concentration and active tonnes, grade and application, COA and impurity parameters, UN number and Class 8 classification, UN packaging format, order quantity and drawdown, sea-freight documentation, a single Incoterm and named port, committed lead time with dual-sourcing terms, and acceptance criteria backed by receiving-side titration. Build that as a fixed template, reuse it across sulfuric acid, hydrochloric acid, and caustic soda lines, and treat public trade figures as context rather than a number to haggle against. Do that and your returned bids stop being a confusing mix and start being a clean, decision-ready comparison.
Sources
- UN Comtrade public trade statistics — China 2025 imports, sulfuric acid (HS 280700): https://comtradeapi.un.org/public/v1/preview/C/A/HS?reporterCode=156&period=2025&cmdCode=280700&flowCode=M&partnerCode=0&partner2Code=0&customsCode=C00&motCode=0&maxRecords=1
- UN Comtrade public trade statistics — China 2025 imports, sodium hydroxide (HS 281512): https://comtradeapi.un.org/public/v1/preview/C/A/HS?reporterCode=156&period=2025&cmdCode=281512&flowCode=M&partnerCode=0&partner2Code=0&customsCode=C00&motCode=0&maxRecords=1
- UN Comtrade public trade statistics — China 2025 imports, ammonia (HS 281410): https://comtradeapi.un.org/public/v1/preview/C/A/HS?reporterCode=156&period=2025&cmdCode=281410&flowCode=M&partnerCode=0&partner2Code=0&customsCode=C00&motCode=0&maxRecords=1
- UN Comtrade public trade statistics — China 2025 imports, nitric acid (HS 280800): https://comtradeapi.un.org/public/v1/preview/C/A/HS?reporterCode=156&period=2025&cmdCode=280800&flowCode=M&partnerCode=0&partner2Code=0&customsCode=C00&motCode=0&maxRecords=1
