DEET for a registered repellent: what transport classification tells you, and why the impurity limit is a regulatory line
In short
- DEET is not regulated for transport — not under ADR/RID, not under IMDG, not under IATA. That simplifies shipping and says nothing about how the material must be labelled, handled or stored.
- The document that actually governs what you can buy is your own product registration, not the supplier's datasheet. The active has to match the one your dossier describes.
N,N-Diethylbenzamide 0.30% max.is the most informative line on the sheet: it names a specific process impurity, which makes it a statement about the route the material was made by.- An assay reported as GC area % is not a mass fraction, and a repellent's label claim is a mass fraction.
- Acid value and moisture are packaging and formulation limits, not purity limits.
DEET has been in commercial use for longer than almost any active ingredient it competes with, and buying it looks simple: one substance, one CAS number, a clear specification. The part that is not simple is that the material is bought by companies whose finished product is regulated, and a regulated product constrains its inputs in ways an ordinary purchase specification does not express.
Transport: not regulated, and what that does not mean
Start with the easy one, because it is genuinely easy and it is the question buyers ask first.
The safety data sheet for the material we supply — N,N-Diethyl-m-toluamide, CAS 134-62-3, EC 205-149-7 — gives the same answer under all three regimes:
| Regime | Classification |
|---|---|
| ADR / RID — European road and rail | Not regulated |
| IMDG — sea | Not regulated |
| IATA — air | Not regulated |
There is no UN number, no packing group and no dangerous-goods declaration, which removes the cost and the lead time that a Class 3 or Class 8 shipment carries. For a buyer used to handling solvents or acids, that is the pleasant surprise on this product.
It is not a statement that the material is harmless. Transport classification asks one question — what happens if this container is damaged in transit — and DEET answers it well. Classification for supply and use is a separate exercise with a separate answer: the substance is classified as harmful if swallowed, irritating to skin and eyes, and hazardous to the aquatic environment. Labelling, workplace exposure control and waste routing follow from that classification, not from the transport one, and the safety data sheet is the document of record for all of it.
The document that governs is your registration
A drum of DEET is an intermediate. What gets sold to a consumer is a repellent, and a repellent is a regulated product almost everywhere it is sold — in the European Union under the biocidal products regime, in the United States under FIFRA, and under national equivalents elsewhere.
That inverts the usual relationship between buyer and specification. Normally the buyer sets a specification for what they need. Here the buyer's own authorisation has already described the active substance they are permitted to use — its identity, its purity, and in many cases its impurity profile — and the purchase specification is downstream of that description rather than upstream of it.
The practical consequence is worth stating plainly: a change in the material that would be unremarkable in an industrial chemical can be a regulatory event in this one. Not because the material got worse, but because it stopped matching the document.
This note does not state the registration status of DEET in any jurisdiction, and no supplier's page should. Status changes, it differs by country and by product type, and the only version that matters to you is the one attached to your own authorisation. What a supplier can do is keep the material inside a window your authorisation already defines, and be able to show that it did.
Why the impurity limit is a regulatory line
The specification published for the DEET we supply reads:
| Parameter | Specification | What it is for |
|---|---|---|
| Assay [area %, GC] | 99.00 min. | Active content, and the label claim downstream |
| N,N-Diethylbenzamide [%] | 0.30 max. | A named process impurity — a statement about route |
| Moisture content [%] | 0.20 max. | Hydrolysis, and emulsion behaviour in formulation |
| Acid value [mg KOH/g] | 0.20 max. | Packaging attack and formulation stability |
| Colour [APHA] | 50 max. | Consumer product appearance; also a process signal |
| Specific gravity [25 °C] | 0.9960 ± 0.0040 | Identity and batch consistency |
| Refractive index | 1.5220 ± 0.0020 | Identity and batch consistency |
Six of those seven lines appear in some form on most specifications. The second one is the one worth reading closely.
DEET is N,N-diethyl-3-methylbenzamide. N,N-Diethylbenzamide is the same molecule without the methyl group on the ring — and it is not a degradation product or a contaminant picked up in handling. It is what you get when the acylating feedstock carries benzoyl chloride alongside the meta-toluoyl chloride the reaction is meant to use. The impurity is inherited from the raw material, which means its level is a property of the route and the feedstock, not of how carefully the batch was finished.
That is why a named impurity limit is more informative than a higher assay figure. A specification that says "99.5% min." and stops has told you a boundary. A specification that says 99.00% min. and names N,N-diethylbenzamide at 0.30% max. has told you what the other fraction mostly is and where it came from. If you are qualifying a second source, the second kind of specification is the one you can actually compare against your first source.
It also explains why an unexplained change in this line deserves a question rather than a tolerance check. A move in the diethylbenzamide level usually means the feedstock changed.
Assay by area %, and the label claim
The assay is reported as GC area %. That is a normalised chromatographic figure, not a mass fraction, and the two are the same number only if every component in the mixture responds to the detector like DEET does.
Most of the time the difference is small enough to ignore. It is worth not ignoring here, because the number at the end of this chain is a legal claim: a repellent labelled at a stated percentage of active is making a statement a regulator can test. A formulator dosing to a mass target from an area-percent assay is carrying that approximation into a label.
The fix is not complicated — ask whether the figure is normalised area percent or determined against a standard, and whether the plant has ever compared the two on this product. A producer that has will tell you. A producer that has not has just told you something as well.
Acid value and moisture: packaging and formulation, not purity
These two are easy to read as generic quality lines and they are not.
Acid value at 0.20 mg KOH/g maximum limits residual acidity. DEET made by the acyl chloride route can carry acid from incomplete workup or from hydrolysis in storage, and free acid matters twice: it attacks the container, and it follows the active into a formulation that usually contains alcohols, emulsifiers and fragrance. A drum arriving inside specification and drifting during a long sea freight and a long warehouse stay is the ordinary way this goes wrong.
Moisture at 0.20% maximum is partly a driver of that drift — water hydrolyses what acid there is to make — and partly a formulation constraint of its own, because water content changes how the active behaves in emulsions and in alcoholic solutions.
Neither line is telling you how much DEET is in the drum. Both are telling you whether the drum will still hold the same material in six months.
What you can check without a laboratory
Colour, specific gravity and refractive index are the three lines a formulator can verify at goods-in with equipment already on site.
Refractive index at 1.5220 ± 0.0020 takes under a minute on a bench refractometer and will not distinguish 99.0% from 99.4% — but it will catch a wrong drum, a mislabel, or dilution, which are the failures that actually happen. Specific gravity at 0.9960 ± 0.0040 does the same job by a different route.
Colour at APHA 50 maximum is the one that carries process information as well. DEET is purified by distillation, and colour developing beyond the usual range is a signal that the material saw more heat or more time than it should have. It also matters commercially in a way an industrial intermediate's colour does not, because the finished product is a consumer good.
What a certificate of analysis should give you
Values measured on your lot, not the specification repeated in the results column. The difference only shows when something goes wrong.
The method behind the assay, and whether it is normalised area percent.
The impurity line filled in with a number, not with "conforms". "Conforms" against a 0.30% limit is compatible with 0.29% and with 0.02%, and those describe different feedstocks.
Lot traceability to a campaign, so that a change you notice can be tied to a change that happened.
Related
- Diethyltoluamide (DEET) — specification, packaging and supply
- Safety data sheet, N,N-Diethyl-m-toluamide (PDF)
Sources. Specification values are those published for the DEET supplied by Palica Chem, CAS 134-62-3, as shown on /deet/. Transport classification, the EC number 205-149-7 and the hazard classification are taken from that product's own safety data sheet, linked above. The chemistry of N,N-diethylbenzamide as a feedstock-derived impurity, and the discussion of assay basis, acid value and moisture, describe general chemistry and formulation practice rather than measurements on any particular lot. No registration or approval status is asserted for any jurisdiction; figures and status for a specific delivery come from that delivery's certificate of analysis and from your own authorisation.