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Reading a CAS-Level Specification Sheet: What Every Column Means

· RIBOLUO CHEMICALS (ZHEJIANG) CO., LTD.

A CAS-level specification sheet fixes one substance by its CAS Registry Number and states the limits the product is held to. It is not a certificate of analysis and not a safety data sheet. Read the columns in that order — identity, limits, provenance — and most errors are visible before a drum is opened.

1. What “CAS-level” does — and does not — mean

A CAS Registry Number identifies a chemical substance. It is assigned by CAS, a division of the American Chemical Society, in a fixed format: two to seven digits, a hyphen, two digits, a hyphen, one check digit — 811-97-2 is R-134a. Because the last digit is a check digit, a malformed number can be caught by arithmetic rather than trust, using the algorithm CAS publishes.

The number does not tell you the grade (one number covers technical and refrigeration qualities — purity and moisture limits live in the specification), the origin (811-97-2 is R-134a whatever entity supplied it), or, for a blend, the composition.

ProductIdentifiers to expectNote
R-134a, 1,1,1,2-tetrafluoroethaneCAS 811-97-2; EC 212-377-0single substance
R-32, difluoromethaneCAS 75-10-5; EC 200-839-4single substance
R-22, chlorodifluoromethaneCAS 75-45-6; EC 200-871-9single substance
Dichloromethane (DCM)CAS 75-09-2; EC 200-838-9single substance, methylene chloride
R-410Acomponents R-32 and R-125 (CAS 354-33-6)two-component blend — no single CAS number
R-404A, R-407Ceach component with its own numberthree-component blends

The trap is the name/number pairing. R-134a is 811-97-2; 75-45-6 is R-22, a different substance under a different phase-down regime. A sheet that takes the name from one place and the number from another should be re-issued, not argued about.

2. Three documents, three jobs

DocumentLevelStatesCannot do
Specification sheetproductthe property limits, with test methods, packing and storagereport what a particular batch measured
Certificate of analysis (COA)batchthe measured result per parameter, for one batchdefine the product; a failed batch still comes with a COA
Safety data sheet (SDS)producthazard classification, handling, transport classification, disposalprove anything about purity

Under REACH, an SDS must reach downstream users for a substance or mixture classified as hazardous under CLP, for PBT/vPvB substances, and for Candidate List substances (ECHA); its format is set by Annex II as amended. The specification sheet is what you buy, the COA is what this batch is, the SDS is what you must do with it.

3. The identity columns

ColumnHow to check it
Product / trade namemust map to one substance, not several
Systematic (IUPAC) name1,1,1,2-tetrafluoroethane = R-134a = HFC-134a
CAS Registry Numberformat plus check digit; confirm name against number on a public substance record
EC / List numberthe EU identifier for the same substance — 212-377-0 for R-134a; must match the SDS
Molecular formulafor a blend there is no single formula — itself the signal
UN number, proper shipping name, classR-134a: UN 3159; DCM: UN 1593 (Class 6.1); R-410A: UN 3163, “Liquefied gas, n.o.s.”
GHS class, pictograms, labelmust agree with the SDS and with the label on the packaging
HS codea customs determination, national in application — confirm with your broker
Batch number, issue date, revisionan undated sheet cannot be tied to the batch you receive

The UN row is where copy-paste damage shows first: a blend moving under a generic “n.o.s.” entry but described with a single-substance entry is a mismatch that reaches the packing instruction.

4. The limit columns: the method column decides what a number means

ParameterWhat it controlsWhat the sheet must state
Assay / purityhow much of the substance is the substancebasis (mass-% or area-%), method, limit, quantification limit
Water contentacid formation and corrosion; reactions in a solventKarl Fischer titration, limit in ppm, sampling point
Aciditylubricant degradation and metal attackmethod and endpoint, limit in a stated unit
Non-condensable gascondenser performance and discharge pressuremethod and limit — often the missing line
Residue on evaporationnon-volatile contaminationgravimetric method and limit
Appearance and odourgross contaminationqualitative, but a cross-check against the batch COA

A limit without a method is not a comparable number. “99.9% minimum” means one thing as mass-% by gas chromatography with an internal standard, and something else as area-% without one. And an absent parameter is not a passing result: if water or non-condensable gas is missing, it was not specified — and those two decide field performance far more often than the assay figure.

5. The environmental columns: GWP, ODP and the basis you must ask for

ProductGWP (AR4)ODPASHRAE class
R-221,8100.055A1
R-410A2,0880A1
R-326750A2L
R-134a1,4300A1
R-404A3,9220A1
R-407C1,7740A1
R-454B4660A2L
R-29030A3

These figures are quoted on the AR4 basis (Fourth Assessment Report). Later reports give different values for the same substance, so a GWP figure without a stated basis cannot be compared with another supplier’s figure. In a market with an HFC quota system this column is also a compliance column: it determines what the shipment consumes — the importer’s question. The safety class is not a label detail either: A2L changes handling, storage, transport and the charge limits for the equipment your customer uses it in. ODP separates the HCFCs from the HFCs, which is why R-22’s phase-out regime differs. One row is context rather than a grade we list: R-454B is not in our listed range, and it appears here so that a buyer planning around it knows that before enquiring — a GWP figure is compared across the market, not offered as a supply list.

6. The provenance columns — and the checks they enable

ColumnWhy it is technical, not administrative
Packing (cylinder, drum, IBC) and declared net weightwithout both, nothing on arrival can be checked
Tare weight and water capacitywithout them net = gross − tare is unverifiable
MOQ and lot sizea small lot from a large batch and a large lot from a small batch differ in traceability
Shelf life, retest interval, storage conditionssets what your warehouse must do; for A2L, ventilation and segregation too
Country of origincustoms and origin rules — not the identity of the producing entity
Issued bythe producer’s own laboratory, or an entity that repacked and tested the lot

Read the last row first: it fixes how far the evidence runs. A COA issued for a repacked lot answers for that lot, not for the batch it came from — both are legitimate, and the buyer should know which is in front of them.

Cross-checkWhat a failure looks like
Registry number on sheet, SDS and labelsheet says 811-97-2, label says 75-45-6
UN number on sheet, SDS and transport documentssheet says UN 3159, transport document says UN 3163
Declared net weight against the packinggross minus tare does not reconcile
SDS composition against the assay rangethe SDS declares a minimum the batch COA does not reach
Batch chain: COA ↔ label ↔ packing listthe COA covers a batch not in the shipment

7. Common traps

  1. One registry number on a blend. Ask for the component list, with a number against each component.
  2. A number belonging to another substance. Have the sheet re-issued.
  3. “Conforms to specification” with no measured value. A conclusion is not a result.
  4. A purity figure with no basis stated — mass-% and area-% are different claims.
  5. No method column, which makes two sheets incomparable even when the limits read alike.
  6. A GWP with no stated assessment-report basis, or a COA covering another batch.

FAQ

Is a specification sheet the same as a certificate of analysis? No. The specification sheet is product-level: limits and methods. The COA is batch-level: measured results against those limits. One defines what you buy, the other shows what the shipment is.

Can I check a CAS number myself? Yes: recalculate the check digit with the algorithm CAS publishes, then confirm on a public substance record that the name and the number describe the same substance — and that the SDS uses the same pair.

Does the same CAS number mean the same quality? No. It identifies the substance, not the grade, purity, packing or origin. Two suppliers can quote one number and deliver specifications that are not interchangeable in your process.

Which GWP basis should a sheet state? The basis must be named, or the figure is not usable. We quote AR4 and say so; if a sheet gives a GWP without naming the assessment report, ask.

What we can provide

Riboluo Chemicals can provide the specification sheet for the grade you are buying with the method stated against each limit, the batch COA for the lot shipped, the SDS and GHS label set, and the transport documents carrying the UN number — with the CAS number stated against the product name.

RIBOLUO CHEMICALS (ZHEJIANG) CO., LTD. is a distributor and trading company, not a manufacturer: we buy from qualified producers and supply under our own documentation (COA, SDS and packing documents).

For general information only — not legal or regulatory advice. Assessment-report bases, phase-down rules and dangerous-goods requirements vary by jurisdiction and change; confirm current obligations and the specification sheet for your grade before ordering.

Sources

Prepared by RIBOLUO CHEMICALS (ZHEJIANG) CO., LTD., a member of Hangrui Group — a chemical distribution platform. We are not a manufacturer: we source from qualified producers and supply under our own documentation (COA, SDS and packing documents).

采购实操 · Riboluo Chemicals can provide.
Need current specs, quota status, or a mixed-load quote for What Every Column Means? Contact tom@riboluo.com with your spec and delivery location.