Diquat dibromide 40% TK is a technical concentrate offer that requires more than a headline assay value. For a formulator, the Certificate of Analysis (CoA) is a lot-specific record used to connect chemical identity, concentration, impurity control, physical behaviour, and release status. A CoA is useful only when the result is tied to a defined specification and analytical method.
Diquat dibromide is identified by CAS RN 85-00-7 in the diquat dibromide 40% TK quality specifications product reference. The intended formulation, destination market, and registration dossier determine which limits and tests apply. FAO/WHO specifications can provide an international reference point, but they do not replace a current national registration, label, safety data sheet (SDS), or an agreed purchase specification.
“40% TK” describes a commercial grade, not a complete quality definition. The percentage basis should be stated explicitly: it may refer to mass fraction, active-equivalent basis, or another basis defined in the supplier specification. The term TK also needs a controlled definition in the technical file. Without that information, two offers carrying the same commercial name may not be directly comparable.
The first review therefore links four records: the quotation, the product specification, the lot CoA, and the formulation or registration requirement. The product name and CAS number establish the starting identity. The specification establishes acceptance limits. The CoA reports one lot against those limits. The formulation brief explains why physical and impurity results matter to the next process.
· Identity is stated as diquat dibromide, with CAS RN 85-00-7 and the relevant salt form.
· The assay basis and nominal 40% grade are defined in the purchase specification.
· The lot number, production date, test date, and sampling date are traceable.
· The destination formulation and legal market are identified before release.
This context prevents a common procurement error: accepting a CoA because the assay appears close to the nominal value while overlooking a different assay basis, an incomplete impurity profile, or a physical property that is unsuitable for downstream processing.
Identity is the first CoA gate. The document should name the active ingredient and salt form rather than relying on a trade name alone. CAS RN 85-00-7 is a useful cross-check, but it is not a substitute for a validated identity test. The test method, reference standard, and result should be recorded in a way that allows the receiving laboratory to understand what was measured.
Assay should show a numerical result, unit, specification limit, and basis. A result expressed as % w/w cannot be compared automatically with a result expressed as g/L. If the formulation is registered on an equivalent basis, the conversion assumptions should be documented and approved by the registration holder. A CoA that states only “passes” gives insufficient information for trend analysis or a technical equivalence review.
The assay result should be read with the method statement. The buyer or formulator should confirm whether the method is a CIPAC method, another recognised method, or a validated internal method. The method name alone is not enough when matrix effects, salt form, or concentration range can influence recovery. A supplier quality agreement can define when method changes require notification and requalification.
· Material name, CAS RN, salt form, grade, and formulation use.
· Lot or batch number and the quantity represented by the CoA.
· Assay result, unit, basis, test method, and acceptance range.
· Analyst or laboratory identification, test date, and authorised release signature.
· A clear statement linking the CoA to the current specification revision.
Where an independent laboratory performs confirmation testing, the comparison should use the same basis and a documented sampling plan. A numerical difference does not automatically prove non-conformity; method uncertainty, sample homogeneity, and agreed tolerance rules need to be considered by the technical team.
Impurity review should not be reduced to a single total value. The relevant profile depends on the manufacturing route, storage history, packaging contact, and intended formulation. A supplier specification should identify the impurities that are known, relevant, or risk-significant for the material. If a limit is not applicable, the technical file should state the reason rather than leaving the field blank.
Formulators commonly ask for a defined profile covering specified impurities, unspecified impurities, total impurities, and degradation products where the risk assessment requires them. The analytical method should distinguish the active ingredient from relevant related substances. Chromatographic data, system suitability, reference standards, and reporting thresholds can be requested under a confidentiality arrangement when the risk or registration programme justifies the request.
Water, acidity or alkalinity, and insoluble matter can affect storage and processing even when assay passes. The appropriate tests and limits must be taken from the agreed specification; no universal numerical limit should be copied from an unrelated formulation. Colour, odour, clarity, and sediment observations may act as useful release indicators, but they should not replace chemical testing.
Stability evidence should connect the test condition to the decision it supports. A short-term retain sample, an accelerated study, and a transport or packaging assessment answer different questions. The record should identify container material, headspace where relevant, temperature, duration, test interval, and appearance or assay changes. A formulator can then determine whether a lot is suitable for immediate processing, extended storage, or only a controlled trial.
A 40% TK can be chemically conforming and still create operational problems. Physical properties should be selected according to the intended downstream product. A liquid formulation may require controlled observations for appearance, homogeneity, sediment, viscosity, density, pH, and ease of redispersion. The exact tests and acceptance limits belong in the formulation specification and should be linked to the finished-product process.
Homogeneity is important because a non-uniform container can produce a non-representative sample and an inconsistent charge to the mixing vessel. Sampling should define container selection, mixing or agitation before sampling where appropriate, sample quantity, retain-sample storage, and chain of custody. The procedure should also state what happens when the material cannot be homogenised without changing its composition.
Compatibility checks should use the actual co-formulants, water quality, equipment materials, and process sequence. Screening may include dissolution, mixing time, filterability, foaming, phase separation, sediment formation, and package interaction. A laboratory result is not automatically transferable to plant scale; mixing energy, transfer lines, temperature control, and hold time can change the outcome.
1. Does the material remain homogeneous during the planned receipt, storage, and charging sequence?
2. Does the assay basis match the finished-product calculation and registration dossier?
3. Are insolubles, colour, pH, or viscosity likely to affect filtration, sprayability, or stability?
4. Does the impurity profile remain within the finished-product risk assessment?
5. Can the supplier provide representative retains and respond to an out-of-specification investigation?
A controlled CoA review begins with document identity. The reviewer confirms the supplier, site, material, grade, lot, specification revision, and test dates. The reviewer then compares every reported result with the current specification, checks units and basis, and records any result reported as a qualitative pass. Missing values should be treated as missing evidence, not as automatic conformity.
Next, the receiving organisation evaluates risk. A new supplier, changed manufacturing site, changed analytical method, unusual appearance, or extended storage period can justify additional testing. The testing plan may include identity, assay, selected impurities, physical properties, and a formulation trial. The scope should be proportionate to the risk and consistent with the quality agreement.
Finally, the approval decision is documented. A conditional release can be appropriate when a defined confirmation test is still pending, provided the material remains segregated and the release authority is named. An out-of-specification result should follow a written investigation process that distinguishes laboratory error, sampling error, manufacturing variation, and genuine non-conformity. Retesting should not be used to erase an original result.
Diquat products are regulated differently across jurisdictions. The importing organisation or registration holder should confirm the current national registration, permitted uses, label language, worker-protection requirements, residue or tolerance requirements, transport classification, and SDS status. EPA material on paraquat and chlorpyrifos illustrates why pesticide regulatory status must be checked by jurisdiction; those examples should not be treated as a diquat-specific legal conclusion.
The purchase contract should define the approved specification, change-notification period, lot traceability, packaging, certificate format, retained samples, non-conformity handling, and document language. The contract can also identify which records are required before shipment, such as CoA, SDS, packing list, certificate of origin, and transport documents. The commercial team should avoid promising a registration outcome based only on a technical grade CoA.
Red Sun’s diquat dibromide 40% TK quality specifications reference can support initial supplier screening. The broader diquat dibromide formulation comparison context can help classify the intended product route, but neither reference replaces an independent technical evaluation or the destination authority’s requirements. A buyer file should retain the quotation, current specification, CoA, sample result, and approval decision so that the basis of the purchase remains auditable.
The highest-priority fields are the fields that can change identity, legal conformity, formulation performance, or safety assessment. For a routine lot from a qualified source, assay and defined physical controls may be the primary release checks, while impurity trending and stability records provide continuing oversight. For a new source or changed process, identity, assay, impurity profile, method suitability, and formulation-fit testing normally receive greater attention.
A practical supplier scorecard can classify each field as critical, major, or supporting. Critical fields block release when absent or outside the approved limit. Major fields require documented technical review. Supporting fields help trend supply quality and investigate future deviations. The classification should be approved by the quality and regulatory functions, not improvised from a single CoA.
CoA area | Decision supported | Review focus |
Identity and assay | Material and concentration conformity | CAS RN, salt form, basis, method, limit |
Specified impurities | Registration and formulation risk | Profile, reporting threshold, trend |
Physical properties | Handling and process fit | Homogeneity, insolubles, pH or viscosity as applicable |
Traceability | Recall and investigation readiness | Lot, site, dates, retain and release authority |
The preferred offer is therefore the offer with a transparent, reproducible quality system and a documented fit for the intended formulation. Nominal assay and price remain relevant, but they should not be the sole supplier-selection criteria.
No. It identifies a commercial grade, while the approved specification must define assay basis, relevant impurities, physical properties, methods, limits, and traceability.
A CoA is a key lot record, but release should follow the receiving organisation’s quality system, specification, sampling plan, and risk-based confirmation testing.
Identity, salt form, lot number, assay basis, specification revision, and test method should be checked before individual numerical results are compared.
No. International specifications support technical evaluation. The current national registration, label, SDS, and applicable pesticide law control the legal market decision.
The lot should be controlled under the quality system and investigated through documented sampling, laboratory, manufacturing, and supplier-corrective-action procedures. Retesting should follow an approved protocol.
A Diquat Dibromide 40% TK CoA matters when it gives the formulator a defensible link between identity, assay, impurity control, physical behaviour, and lot traceability. A complete review combines the current specification, validated methods, representative sampling, formulation-fit evidence, and jurisdiction-specific regulatory checks. The diquat dibromide supplier qualification record can support initial screening, while the importing organisation remains responsible for qualification, release, and registration compliance.
