All fentanyl, legal or otherwise, starts out as a powder (generally as the salt, fentanyl citrate, though illicit labs produce a number of variations...). You're right that there is no powdered form sold legally, but most of the illicit sales come from labs in Mexico and China, and is indeed in powdered form.
Far better: "I cannot pretend to understand how you're feeling", "I can't imagine...". Perhaps with "I can only appreciate how difficult it may be", and so on.
One thing remains the same, it's always my least favorite task as a paramedic.
"I feel how weak and fruitless must be any word of mine which should attempt to beguile you from the grief of a loss so overwhelming."
http://www.sirchie.com/nark20033-fentanyl-reagent.html#.V8uE...
The problem is, it's a destructive test, which makes it unattractive to both dealers and users, as it requires wasting at least some of the product.
Seems strange, when tests for other drugs are available.
That will hopefully be changing soon (at least in the US): http://www.wsj.com/articles/u-s-china-reach-agreement-to-ste...
I'm a paramedic in a nice suburban area. I've been doing this a little over a decade now. I managed to make it a good long while without having to deliver life changing news to a parent. In the past two years I've done it way too many times.
I'm so sorry for your loss. I have witnessed your pain in others, and I know that it's beyond my comprehension...