windshaper, do you have any documentation on the Mallinckrodt patches? Are they polymer matrix or gel? If they are polymer matrix I would do a dry methanol extraction. Methanol is available commonly as "Splash" gas line de-icer. In the case of splash, it's available as pure methanol, with zero lubricants. In fact, I evaporated a lot of it and found zero residue afterwards.
What you can do is find a very small glass, bigger than a shot glass but close. Then cut the patch in half, place the patch sticky side up on the bottom of the glass, and put 1 cm of methanol on top of it. Wait for 30 minutes, stirring every 8 minutes and remove the half and place the second half in place and do the same thing for another 30 minutes.
After the second 30, remove the second patch half. The next step is to slowly evaporate the methanol. Methanol is not as aromatic as IPA (Isopropyl) so it will take a long time to evaporate. There are 2 ways to do this.
1) Watch glass or small curved bottom dish. Pour your solution into a small dish, or watch glass and put a small fan on it and let it evaporate.
2) Takes much longer, but, you can simply tilt the glass on it's side so that air can get in and evaporate the methanol. Last time it took over 24 hours to evaporate this way.
Once done, you will be left with a white crystal powder, this is pure fentanyl. If you don't have the powder, then the extraction was unsuccessful. I would bet that those patches will work just fine with a methanol extraction if they are polymer matrix.
Fentanyl, like many many drugs is highly soluble in methanol. In fact, to combat this, many pill manufacturers have started adding excipients into pills which are also soluble in methanol to prohibit an alcohol extraction. I have not seen any evidence of this yet with patches. Even with these excipients extractions are still highly possible, however, your yields are smaller with these types of pills. Anyway, I diverge, but with the case of the patches, extraction is highly probable with Methanol. Plus, you get an almost quantitative yield, literally, you get almost 100% of the product extracted. It's incredibly high.
If successful, the most important part is the next one. Dosing and titration. You need to titrate the powder with 1CC of Lemon Juice (citric acid) and add 2 more CC's of water and stir to make sure it's all dissolved. I typically add another 7 CC after this to have a total of 10CC of solution. This is where this is most dangerous. Depending on your extraction, you will either have 7.5 mg of Fentanyl (75mcg/hr) or less of Fentanyl in solution. Actually, to be specific, technically, you will have 57% more than this by mass of Fentanyl Citrate, but, if going on Freebase mass, you 'll have the above amount.
It's important to always start at the smallest possible dose when using this method, the reason is simple. One day you may recover 50% of the Fentanyl if the extraction isn't done right, and you'll get use to a certain dose. Well, on the next occasion you could be successful and have a 100% extraction. The dosing with this amount is much more critical than the first extraction. So, after every extraction, it's very important to get the dosing re-calculated for safety.
One other thing. On a personal note, I've noticed that the tolerance period for Fentanyl is very very short. After just a couple of days, I found it easy to build a tolerance to 10,000 mcg a day. To me this is kinda scary. So, I wouldn't use this for more than a couple of days unless you're very good at pacing. I say this because of the reading I've done on Fentanyl and the unknown mechanisms of overdose mentioned on Wikipedia. The fact that there are mechanisms that are unknown is scary to me. Even though they are extremely rare, they still exist. Or, perhaps they are not as rare as they let on....