Procurement
How to specify a blend
The five lines that decide whether a quotation is comparable — and the words that make a tender specification auditable.
Five lines do most of the work
A semiochemical quotation is only comparable if it states the same five things. When a specification omits them, suppliers fill the gaps differently and the price difference is usually a grade difference in disguise.
- Compound and CAS number. The name alone is ambiguous — the same name can cover different isomeric mixtures.
- Isomeric composition. (E)/(Z) ratio, or “defined mixture” with the proportions stated. This is the line that decides whether the lure behaves.
- Assay basis. By GC area percent, or by an internal standard? The two are not interchangeable.
- Packing and net weight. A 1 kg pack of a 95% material is not a 1 kg pack of a 98% material in terms of what the blend actually receives.
- Documentation set. Certificate of analysis, GC trace, SDS, and whether an isomer statement is included.
Blend specification, not compound specification
Where a program buys a formulated blend rather than components, the specification should state the composition of the mixture and the tolerance on each component. A blend specified as “Ips lure” is not a specification; a blend specified as three components with stated percentages and stated isomer geometry is.
Two practical additions: state the dispenser type the blend is designed for, and state the intended flight period. A blend tuned for a short spring flight and one tuned for a two-generation season are different products even when the components match.
Wording that makes a tender auditable
- “Isomeric composition to be stated on the certificate of analysis for each lot.”
- “Retained sample to be held for a minimum of 24 months and made available on request.”
- “Safety data sheet in [language], compliant with [regulation].”
- “Lot number to appear on certificate, packing list and delivery note.”
- “Method statement to be supplied where assay results are disputed.”
What to leave out
Avoid specifying a brand name, and avoid “or equivalent” without a defined equivalence test — it invites a substitution that passes paperwork and fails in the field. If an equivalent is acceptable, define it as: same CAS, isomer within stated tolerance, assay within stated tolerance, documentation set identical.
Development quantities
Most programmes should test before committing. Development quantities below the standard pack let a blend be trialled for a season, and the same lot documentation applies, so a trial result can be compared with a later bulk delivery. Ask for the split explicitly in the quotation; it is not always offered unless requested.
Send the specification
If you have a tender document, send it as it stands. We respond in the same structure — compound, CAS, isomer, assay basis, packing, documentation, delivery — so the bid can be assessed line by line rather than in prose.