I'm less familiar with the US CFR than with the equivalent EU regs, but IIRC it includes a provision that, for concentrated products made from a single ingredient, the residue limits are applicable for the product as reconstituted to single strenght - i.e. it recognises that this is not a "dilution" per se.
Again I can really only talk from an informed position from the EU perspective, but to me 10% seems somewhat arbitrary and may thus be difficult to specifically defend?
I'd contact the suppliers of the various components to see if they can give you an effective concentration factor for the product - for example, if it takes 100kg of the starting botanical to make 1kg of extracted oils then this is arguably a nominal 100-fold concentration factor. You should then be able to advise the lab of this when sending the samples for analysis, so they can take into account when preparing the report. If they can't/won't do this for you then try other labs, as it's something I've seen very routinely for various products with a known concentration factor - you'll get e.g. a table of direct actual results, and a second column showing the result taking the concentration factor into account, and the latter would then be used for the conclusion/opinion section (if they're including one).
Edited to add: From a very quick scan, 40CFR180.1 (h)(10) looks like it could be helpful here:
(10) For processed foods consisting primarily of one ingredient and sold in a form requiring further preparation prior to consumption (e.g., fruit juice concentrates, dehydrated vegetables, and powdered potatoes), the processed food to be examined for residues shall be the whole processed commodity after compensating for or reconstituting to the commodity's normal moisture content, unless a tolerance for the concentrated or dehydrated food form is included in this part. If there exists a tolerance for a specific pesticide on the processed food in its concentrated or dehydrated food form, for the purpose of determining whether the food is in compliance with that tolerance, the processed food to be examined for residues shall be the whole processed commodity on an “as is” basis.
Edited by pHruit, 01 September 2020 - 07:50 AM.